Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Sep. 30, 2017	Nov. 02, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
Entity Registrant Name	AMERICAN SUPERCONDUCTOR CORP /DE/
Trading Symbol	AMSC
Entity Central Index Key	0000880807
Current Fiscal Year End Date	--03-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		20,925,142

Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017
Current assets:
Cash and cash equivalents	$ 30,320	$ 26,784
Accounts receivable, net	8,193	7,956
Inventory	15,983	17,462
Prepaid expenses and other current assets	3,323	2,703
Restricted cash	0	795
Total current assets	57,819	55,700
Property, plant and equipment, net	36,438	43,438
Intangibles, net	3,496	301
Goodwill	1,711	0
Restricted cash	165	165
Deferred tax assets	538	407
Other assets	381	233
Total assets	100,548	100,244
Current liabilities:
Accounts payable and accrued expenses	14,016	14,490
Note payable, current portion, net of discount of $19 as of March 31, 2017	0	1,481
Derivative liabilities	1,224	1,923
Deferred revenue	16,069	14,323
Total current liabilities	31,309	32,217
Deferred revenue	8,325	7,631
Deferred tax liabilities	125	125
Other liabilities	137	45
Total liabilities	39,896	40,018
Commitments and contingencies (Note 14)
Stockholders' equity:
Common stock	211	147
Additional paid-in capital	1,039,458	1,017,510
Treasury stock	(1,645)	(1,371)
Accumulated other comprehensive income (loss)	718	(503)
Accumulated deficit	(978,090)	(955,557)
Total stockholders' equity	60,652	60,226
Total liabilities and stockholders' equity	$ 100,548	$ 100,244

Unaudited Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenues	$ 11,049	$ 18,507	$ 19,971	$ 31,852
Cost of revenues	10,777	16,404	24,186	28,886
Gross margin	272	2,103	(4,215)	2,966
Operating expenses:
Research and development	2,951	2,867	5,667	5,819
Selling, general and administrative	5,339	6,347	11,477	13,563
Amortization of acquisition-related intangibles	0	39	13	78
Change in fair value of contingent consideration	(201)	0	(201)	0
Restructuring	(12)	0	1,328	0
Total operating expenses	8,077	9,253	18,284	19,460
Operating loss	(7,805)	(7,150)	(22,499)	(16,494)
Change in fair value of warrants	144	1,244	1,069	567
Gain on sale of minority interest	951	0	951	0
Interest income (expense), net	54	(107)	45	(243)
Other expense, net	(796)	(518)	(2,170)	(393)
Loss before income tax (benefit) expense	(7,452)	(6,531)	(22,604)	(16,563)
Income tax (benefit) expense	(171)	794	(71)	1,117
Net loss	$ (7,281)	$ (7,325)	$ (22,533)	$ (17,680)
Net loss per common share
Basic (in dollars per share)	$ (0.38)	$ (0.53)	$ (1.26)	$ (1.29)
Diluted (in dollars per share)	$ (0.38)	$ (0.53)	$ (1.26)	$ (1.29)
Weighted average number of common shares outstanding
Basic (in shares)	19,060	13,769	17,925	13,723
Diluted (in shares)	19,060	13,769	17,925	13,723

Unaudited Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (7,281)	$ (7,325)	$ (22,533)	$ (17,680)
Other comprehensive gain (loss), net of tax:
Foreign currency translation gain (loss)	401	111	1,221	(541)
Total other comprehensive gain (loss), net of tax	401	111	1,221	(541)
Comprehensive loss	$ (6,880)	$ (7,214)	$ (21,312)	$ (18,221)

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net loss	$ (22,533)	$ (17,680)
Adjustments to reconcile net loss to net cash used in operations:
Depreciation and amortization	7,682	3,735
Stock-based compensation expense	1,232	1,653
Provision for excess and obsolete inventory	351	671
Gain on sale of minority interest	(951)	0
Change in fair value of warrants and contingent consideration	(1,270)	(567)
Non-cash interest expense	19	98
Other non-cash items	(97)	(103)
Changes in operating asset and liability accounts:
Accounts receivable	124	7,118
Inventory	1,354	(8,696)
Prepaid expenses and other current assets	85	2,843
Accounts payable and accrued expenses	(770)	(4,481)
Deferred revenue	1,235	4,497
Net cash used in operating activities	(13,539)	(10,912)
Cash flows from investing activities:
Purchase of property, plant and equipment	(483)	(359)
Proceeds from the sale of property, plant and equipment	12	15
Change in restricted cash	795	4
Cash paid for acquisition, net of cash acquired	134	0
Proceeds from sale of minority interest	951	0
Change in other assets	(130)	(28)
Net cash provided by/(used in) investing activities	1,279	(368)
Cash flows from financing activities:
Employee taxes paid related to net settlement of equity awards	(274)	(490)
Repayment of debt	(1,575)	(2,000)
Proceeds from public equity offering, net	16,952	0
Proceeds from exercise of employee stock options and ESPP	85	0
Net cash provided by/(used in) financing activities	15,188	(2,490)
Effect of exchange rate changes on cash and cash equivalents	608	(298)
Net increase/(decrease) in cash and cash equivalents	3,536	(14,068)
Cash and cash equivalents at beginning of year	26,784	39,330
Cash and cash equivalents at end of year	30,320	25,262
Supplemental schedule of cash flow information:
Issuance of common stock in connection with the purchase of Infinia Technology Corporation	3,557	0
Cash paid for income taxes, net of refunds	753	894
Issuance of common stock to settle liabilities	185	212
Cash paid for interest	$ 42	$ 187

Nature of the Business and Operations and Liquidity	6 Months Ended
Nature of the Business and Operations and Liquidity	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business and Operations and Liquidity	Nature of the Business and Operations and Liquidity Nature of the Business and Operations American Superconductor Corporation (“AMSC” or the “Company”) was founded on April 9, 1987. The Company is a leading provider of megawatt-scale solutions that lower the cost of wind power and enhance the performance of the power grid. In the wind power market, the Company enables manufacturers to field wind turbines through its advanced engineering, support services and power electronics products. In the power grid market, the Company enables electric utilities and renewable energy project developers to connect, transmit and distribute power through its transmission planning services and power electronics and superconductor-based products. The Company’s wind and power grid products and services provide exceptional reliability, security, efficiency and affordability to its customers. These unaudited condensed consolidated financial statements of the Company have been prepared on a going concern basis in accordance with United States generally accepted accounting principles (“GAAP”) and the Securities and Exchange Commission’s (“SEC”) instructions to Form 10-Q. The going concern basis of presentation assumes that the Company will continue operations and will be able to realize its assets and discharge its liabilities and commitments in the normal course of business. Certain information and footnote disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those instructions. The year-end condensed balance sheet data was derived from audited financial statements but does not include all disclosures required by GAAP. The unaudited condensed consolidated financial statements, in the opinion of management, reflect all adjustments (consisting of normal recurring adjustments) necessary for a fair statement of the results for the interim periods ended September 30, 2017 and 2016 and the financial position at September 30, 2017. Liquidity The Company has experienced recurring operating losses and as of September 30, 2017, the Company had an accumulated deficit of $978.1 million. In addition, the Company has experienced recurring negative operating cash flows. At September 30, 2017, the Company had cash and cash equivalents of $30.3 million, with no outstanding debt. Cash used in operations for the six months ended September 30, 2017 was $13.5 million. From April 1, 2011 through the date of this filing, the Company has reduced its global workforce substantially, including a restructuring action announced on April 4, 2017 which led to a $1.3 million restructuring charge in the six months ended September 30, 2017. See Note 15 "Restructuring" for further discussion of this action. The Company has taken actions to consolidate certain business operations to reduce facility costs. As of September 30, 2017, the Company had a global workforce of 321 persons. The Company plans to closely monitor its expenses and, if required, expects to further reduce operating costs and capital spending to enhance liquidity. Over the last several years, the Company has entered into equity financing arrangements in order to enhance liquidity. Since April 1, 2012, the Company has generated aggregate cash flows from financing activities of $85.1 million. Included in this amount are proceeds of approximately $17.0 million after deducting underwriting discounts and commissions and offering expenses payable by the Company, from the Company's equity offering completed on May 10, 2017, which includes the subsequent exercise by the underwriters of their option in full to purchase additional shares. The Company terminated its At Market Issuance Sales Agreement ("ATM") with FBR Capital Markets & Co. in conjunction with this equity offering. See Note 13 “Stockholder's Equity” for further discussion of these financing arrangements. In December 2015, the Company entered into a set of strategic agreements valued at approximately $210.0 million with Inox Wind Ltd. (“Inox”), which includes a multi-year supply contract pursuant to which the Company will supply electric control systems to Inox and a license agreement allowing Inox to manufacture a limited number of electrical control systems. After Inox purchases the specified number of electrical control systems required under the terms of the supply contract, Inox agreed that the Company will continue as Inox’s preferred supplier and Inox will be required to purchase from the Company a majority of its electric control systems requirements for an additional three-year period. The Company believes that based on the information presented above and its quarterly management assessment, it has sufficient liquidity to fund its operations and capital expenditures for the next twelve months following the issuance of the financial statements for the six months ended September 30, 2017. The Company’s liquidity is highly dependent on its ability to increase revenues, its ability to control its operating costs, and its ability to raise additional capital, if necessary. There can be no assurance that the Company will be able to continue to raise additional capital from other sources or execute on any other means of improving liquidity described above.

Stock-Based Compensation

6 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-Based Compensation

The Company accounts for its stock-based compensation at fair value. The following table summarizes stock-based compensation expense by financial statement line item for the three and six months ended September 30, 2017 and 2016 (in thousands):



	Three months ended September 30,				Six months ended September 30,
	2017		2016		2017		2016
Cost of revenues	$	23	$	49	$	59	$	99
Research and development	61		62		110		92
Selling, general and administrative	394		542		1,063		1,462
Total	$	478	$	653	$	1,232	$	1,653

The Company issued 37,140 shares of immediately vested common stock and 795,500 shares of restricted stock awards during the six months ended September 30, 2017, and issued 35,000 shares of immediately vested common stock, and granted 126,000 restricted stock awards during the six months ended September 30, 2016. These restricted stock awards generally vest over 2-3 years. Awards for restricted stock include both time-based and performance-based awards. For options and awards that vest upon the passage of time, expense is being recorded over the vesting period. Performance-based awards are expensed over the requisite service period based on probability of achievement. In addition, the Company issued 16,667 restricted stock units under the 2007 Stock Incentive Plan during the six months ended September 30, 2017, each of which represents the right to receive one share of common stock in connection with a severance agreement entered into with one of the Company's former executive officers. These restricted stock units vested and were settled in shares of common stock on the eighth day after receipt of an irrevocable release.

The estimated fair value of the Company’s stock-based awards, less expected annual forfeitures, is amortized over the awards’ service period. The total unrecognized compensation cost for unvested outstanding stock options was $0.3 million at September 30, 2017. This expense will be recognized over a weighted average expense period of approximately 1.5 years. The total unrecognized compensation cost for unvested outstanding restricted stock was $3.6 million at September 30, 2017. This expense will be recognized over a weighted-average expense period of approximately 2.1 years.

The Company did not grant any stock options during the three and six months ended September 30, 2017. During the six months ended September 30, 2016, the Company granted 9,703 stock options. These options will vest over 2 years. The weighted average assumptions used in the Black Scholes valuation model for stock options granted during the six months ended September 30, 2016 are as follows:.



	September 30, 2017	September 30, 2016		September 30, 2017	September 30, 2016
Expected volatility	N/A	67.6	%	N/A	67.6	%
Risk-free interest rate	N/A	1.3	%	N/A	1.3	%
Expected life (years)	N/A	5.7		N/A	5.7
Dividend yield	N/A	None		N/A	None

Computation of Net Loss per Common Share

6 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Computation of Net Loss per Common Share

Basic net loss per share (“EPS”) is computed by dividing net loss by the weighted-average number of common shares outstanding for the period. Where applicable, diluted EPS is computed by dividing the net loss by the weighted-average number of common shares and dilutive common equivalent shares outstanding during the period, calculated using the treasury stock method. Common equivalent shares include the effect of restricted stock, exercise of stock options and warrants and contingently issuable shares. For the three and six months ended September 30, 2017, 1.5 million shares were not included in the calculation of diluted EPS as they were considered anti-dilutive, of which 0.3 million relate to outstanding stock options, and 1.2 million relate to outstanding warrants. For the three and six months ended September 30, 2016, 1.6 million shares were not included in the calculation of diluted EPS as they were considered anti-dilutive, of which 0.4 million relate to outstanding stock options, and 1.2 million relate to outstanding warrants.

The following table reconciles the numerators and denominators of the earnings per share calculation for the three and six months ended September 30, 2017 and 2016 (in thousands, except per share data):



	Three months ended September 30,						Six months ended September 30,
	2017			2016			2017			2016
Numerator:
Net loss	$	(7,281	)	$	(7,325	)	$	(22,533	)	$	(17,680	)
Denominator:
Weighted-average shares of common stock outstanding	19,531			14,190			18,316			14,161
Weighted-average shares subject to repurchase	(471		)	(421		)	(391		)	(438		)
Shares used in per-share calculation ― basic	19,060			13,769			17,925			13,723
Shares used in per-share calculation ― diluted	19,060			13,769			17,925			13,723
Net loss per share ― basic	$	(0.38	)	$	(0.53	)	$	(1.26	)	$	(1.29	)
Net loss per share ― diluted	$	(0.38	)	$	(0.53	)	$	(1.26	)	$	(1.29	)

Acquisitions and Related Goodwill

6 Months Ended

Sep. 30, 2017

Business Combinations [Abstract]

Acquisitions an Related Goodwill

Acquisition and Related Goodwill

Acquisition of Infinia Technology Corporation

On September 25, 2017, the Company acquired Infinia Technology Corporation ("ITC") for approximately $3.8 million as described below (the "Acquisition"). Located in Richmond, Washington, ITC is a technology firm founded in 2009 specializing in the design, development and commercialization of cryo-coolers for a wide range of applications.

Pursuant to the terms of the stock purchase agreement ("SPA"), the Company acquired all of the issued and outstanding shares of ITC (the "ITC Shares") from the selling stockholders, for a purchase price of approximately $3.8 million consisting of $0.1 million in cash and 884,890 shares of the Company’s common stock (the "AMSC Shares"), $0.01 par value per share at a per share price of $4.02 on the acquisition date. Under the terms of the SPA, the Company was obligated to file a registration statement (the "Resale Registration Statement") covering the resale of the AMSC Shares by the selling stockholders no later than 10 business days following the closing of the Acquisition, and to use commercially reasonable efforts to cause the Resale Registration Statement to be declared effective by the SEC as soon as practicable thereafter. Additionally, the Company agreed to pay the selling stockholders in cash (the "Make Whole Payment"), if any, equal to (x) an amount equal to (i) the price per AMSC Share pursuant to the terms of the SPA, multiplied by (ii) the number of AMSC Shares sold by the selling stockholders during the first 90 days after the effectiveness of the Resale Registration Statement, minus (y) the aggregate sales proceeds received by the Selling Stockholders from the sale of any AMSC Shares during the first 90 days after the effectiveness of the Resale Registration Statement. The Resale Registration Statement was declared effective on October 23, 2017. The Company has granted a security interest in the ITC Shares to the selling stockholders to secure the Company’s obligation to make any Make Whole Payment. The contingent liability related to the Make Whole Payment was determined under a fair value option based pricing model to be $0.6 million on September 25, 2017.

ITC was integrated into the Company's Grid business unit. The Acquisition has been accounted for under the purchase method of accounting in accordance with ASU 805, Business Combinations. The Company allocated the purchase price to the assets acquired and liabilities assumed at their estimated fair values as of the date of Acquisition. The Company estimated the fair value of the intangible assets at $3.4 million, which consisted of core-technology and know-how, working capital of $0.2 million and property, plant and equipment of less than $0.1 million. A long-term deferred tax liability of $1.1 million was recorded for the differing book and tax basis of the ITC assets and liabilities. Provisional amounts have been recorded for the related tax activity as of September 30, 2017. Final adjustments are expected to be made during the third quarter of fiscal 2017.

The following table summarizes the consideration paid for ITC and the amounts of the assets acquired and liabilities assumed recognized at the acquisition date, as well as the fair value at the acquisition date of ITC at September 25, 2017 (in millions):



	September 25, 2017
Consideration
Cash	$	0.1
Equity (884,890 shares of common stock at $4.02 per share)	3.6
Contingent consideration	0.6
Total Consideration	$	4.3

Recognized amounts of identifiable assets acquired and liabilities assumed
Core technology and know-how	$	3.4
Working capital	0.2
Property, plant and equipment	0.0
Total identifiable net assets	$	3.6
Long-term deferred tax liability	1.1
Goodwill allocated	$	1.7

The Company valued the Acquisition at $4.2 million (excluding Acquisition costs), using a value of $4.02 per share, which was the closing price of the Company's common stock on the date of Acquisition plus $0.1 million in cash and $0.6 million of contingent consideration for the Make Whole Payment valued as of the closing date. Acquisition costs of less than $0.1 million were recorded in selling, general and administrative costs.

The results of ITC's operations, which were not significant from the date of acquisition until September 30, 2017, are included in the Company’s consolidated results from the date of Acquisition of September 25, 2017, for the three and six months ended September 30, 2017. Assuming the Acquisition had occurred on April 1, 2017 and 2016, the impact on the consolidated results of the Company would not have been significant.

Goodwill

At the time of the Acquisition, the Company allocated the purchase price to the assets acquired and liabilities assumed at their estimated fair values as of the date of Acquisition. The excess of the purchase price of $1.7 million paid by the Company over the estimated fair value of net assets acquired has been recorded as goodwill in the Company's Grid segment. Goodwill represents the value associated with the acquired workforce and synergies related to the merger of the two companies.

The guidance under ASC 805-30 provides for the recognition of goodwill on the Acquisition date measured as the excess of the aggregate consideration transferred over the net of the Acquisition date amounts of net assets acquired and liabilities assumed. The fair value of the contingent consideration included in the total consideration transferred was determined using the Black Scholes pricing model, and all other consideration transferred was calculated using its observable market fair value. The tangible net assets acquired fair value was based on observable market fair value. The acquired intangible asset fair value was determined using discounted cash flows under an excess in earnings model.

Goodwill represents the difference between the purchase price and the fair value of the identifiable tangible and intangible net assets when accounted for using the purchase method of accounting. Goodwill is not amortized, but reviewed for impairment. Goodwill is reviewed annually, and whenever events or changes in circumstances indicate that the carrying value of the goodwill might not be recoverable.

The Company early adopted ASU 2017-04 as of September 30, 2017. The Company will perform an annual impairment assessment on goodwill, unless events occur in the interim periods to indicate impairment may have occurred. The Company did not identify any triggering events in the period between the date of Acquisition and September 30, 2017, which would require subsequent interim testing of goodwill. As such, the Company expects to perform its annual goodwill impairment test during the fourth fiscal quarter of 2017. The Company will compare the fair value of its reporting unit to its carrying value. If the carrying value of the net assets assigned to the reporting unit exceeds the fair value of the reporting unit, then the Company would record an impairment loss equal to the difference.

Fair Value Measurements

6 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

A valuation hierarchy for disclosure of the inputs to valuation used to measure fair value has been established. This hierarchy prioritizes the inputs into three broad levels as follows:



Level 1	-	Inputs are unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

Level 2	-	Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability, and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs).

Level 3	-	Unobservable inputs that reflect the Company’s assumptions that market participants would use in pricing the asset or liability. The Company develops these inputs based on the best information available, including its own data.

The Company provides a gross presentation of activity within Level 3 measurement roll-forward and details of transfers in and out of Level 1 and 2 measurements. A change in the hierarchy of an investment from its current level is reflected in the period during which the pricing methodology of such investment changes. Disclosure of the transfer of securities from Level 1 to Level 2 or Level 3 is made in the event that the related security is significant to total cash and investments. The Company did not have any transfers of assets and liabilities from Level 1 and Level 2 to Level 3 of the fair value measurement hierarchy during the three and six months ended September 30, 2017.

A financial asset’s or liability’s classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement.

The following table provides the assets and liabilities carried at fair value on a recurring basis, measured as of September 30, 2017 and March 31, 2017 (in thousands):



	Total Carrying Value		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
September 30, 2017:
Assets:
Cash equivalents	$	24,392	$	24,392	$	—	$	—
Derivative liabilities:
Acquisition contingent consideration	$	370	$	—	$	—	$	370
Warrants	854		—		—		854
Total derivative liabilities	$	1,224	$	—	$	—	$	1,224



	Total Carrying Value		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
March 31, 2017:
Assets:
Cash equivalents	$	14,105	$	14,105	$	—	$	—
Derivative liabilities:
Warrants	$	1,923	$	—	$	—	$	1,923

The table below reflects the activity for the Company’s major classes of liabilities measured at fair value on a recurring basis (in thousands):



	Warrants			Acquisition Contingent Consideration
April 1, 2017	$	1,923		$	—
Issuance of contingent consideration	—			571
Mark to market adjustment	(1,069		)	(201		)
Balance at September 30, 2017	$	854		$	370



	Warrants
April 1, 2016	$	3,227
Mark to market adjustment	(1,304		)
Balance at March 31, 2017	$	1,923

Valuation Techniques

Cash Equivalents

Cash equivalents consist of highly liquid instruments with maturities of three months or less that are regarded as high quality, low risk investments and are measured using such inputs as quoted prices, and are classified within Level 1 of the valuation hierarchy. Cash equivalents consist principally of certificates of deposits and money market accounts.

Warrants

Warrants were issued in conjunction with a Securities Purchase Agreement (the “Purchase Agreement”) with Capital Ventures International (“CVI”) in April 2012, an equity offering to Hudson Bay Capital in November 2014, and a Loan and Security Agreement with Hercules Technology Growth Capital, Inc. (“Hercules”) in June 2012 and through subsequent amendments. See Note 11, “Debt,” and Note 12 “Warrants and Derivative Liabilities,” for additional information. These warrants are subject to revaluation at each balance sheet date, and any change in fair value will be recorded as a change in fair value in derivatives and warrants until the earlier of their exercise or expiration.

The Company relies on various assumptions in a lattice model to determine the fair value of warrants. The Company has valued the warrants within Level 3 of the valuation hierarchy. See Note 12, “Warrants and Derivative Liabilities,” for a discussion of the warrants and the valuation assumptions used.

Contingent Consideration

Contingent consideration relates to a make whole payment provision set forth in the SPA that requires the Company to guarantee the purchase price of the acquisition should the aggregate proceeds of the resale of AMSC shares sold by selling stockholders during the first 90 days after the effectiveness of the Resale Registration Statement be less than the agreed upon purchase price for such AMSC Shares (per the terms of the SPA) sold during such 90 day period. See Note 12, "Warrants and Derivative Liabilities" and Note 4, “Acquisition and Related Goodwill” for further discussion. The Company relied on a Black Scholes option pricing method to determine the fair value of the contingent consideration on the date of acquisition and will continue to revalue the fair value of the contingent consideration at each subsequent balance sheet date until the final settlement date, with the change in fair value recorded in the current period operating loss.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Accounts Receivable

6 Months Ended

Sep. 30, 2017

Receivables [Abstract]

Accounts Receivable

Accounts receivable at September 30, 2017 and March 31, 2017 consisted of the following (in thousands):



	September 30, 2017			March 31, 2017
Accounts receivable (billed)	$	7,620		$	7,436
Accounts receivable (unbilled)	627			574
Less: Allowance for doubtful accounts	(54		)	(54		)
Accounts receivable, net	$	8,193		$	7,956

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Inventory

6 Months Ended

Sep. 30, 2017

Inventory Disclosure [Abstract]

Inventory

Inventory at September 30, 2017 and March 31, 2017 consisted of the following (in thousands):



	September 30, 2017		March 31, 2017
Raw materials	$	5,776	$	4,263
Work-in-process	1,010		426
Finished goods	6,543		8,016
Deferred program costs	2,654		4,757
Net inventory	$	15,983	$	17,462

The Company recorded inventory write-downs of $0.1 million and $0.4 million for the three and six months ended September 30, 2017. The Company recorded inventory write-downs of $0.4 million and $0.7 million for the three and six months ended September 30, 2016. These write downs were based on evaluating its inventory on hand for excess quantities and obsolescence.

Deferred program costs as of September 30, 2017 and March 31, 2017 primarily represent costs incurred on programs accounted for under contract accounting where the Company needs to complete development milestones before revenue and costs will be recognized.

Property, Plant and Equipment

6 Months Ended

Sep. 30, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

The cost and accumulated depreciation of property and equipment at September 30, 2017 and March 31, 2017 are as follows (in thousands):



	September 30, 2017			March 31, 2017
Land	$	3,643		$	3,643
Construction in progress - equipment	606			601
Buildings	34,549			34,549
Equipment and software	73,798			73,445
Furniture and fixtures	1,154			1,201
Leasehold improvements	1,912			2,442
Property, plant and equipment, gross	115,662			115,881
Less accumulated depreciation	(79,224		)	(72,443		)
Property, plant and equipment, net	$	36,438		$	43,438

Depreciation expense was $3.2 million and $7.5 million for the three and six months ended September 30, 2017. Depreciation expense was $1.7 million and $3.5 million for the three and six months ended September 30, 2016. Included in depreciation expense for the three and six months ended September 30, 2017 is $1.6 million and $4.1 million, respectively, of accelerated depreciation recorded to cost of revenues related to revised estimates of the remaining useful lives of certain pieces of manufacturing equipment.

Accounts Payable and Accrued Expenses

6 Months Ended

Sep. 30, 2017

Payables and Accruals [Abstract]

Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses at September 30, 2017 and March 31, 2017 consisted of the following (in thousands):



	September 30, 2017		March 31, 2017
Accounts payable	$	4,089	$	3,207
Accrued inventories in-transit	86		313
Accrued other miscellaneous expenses	1,628		2,240
Accrued restructuring	493		—
Accrued compensation	3,674		5,042
Income taxes payable	2,194		1,344
Accrued warranty	1,852		2,344
Total	$	14,016	$	14,490

The Company generally provides a one to three year warranty on its products, commencing upon installation. A provision is recorded upon revenue recognition to cost of revenues for estimated warranty expense based on historical experience.

Product warranty activity was as follows (in thousands):



	Three months ended September 30,						Six months ended September 30,
	2017			2016			2017			2016
Balance at beginning of period	$	2,026		$	2,774		$	2,344		$	3,601
Change in accruals for warranties during the period	86			316			127			417
Settlements during the period	(260		)	(396		)	(619		)	(1,324		)
Balance at end of period	$	1,852		$	2,694		$	1,852		$	2,694

Income Taxes	6 Months Ended
Income Taxes	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company recorded income tax benefits of $0.2 million and $0.1 million in the three and six months ended September 30, 2017. The Company recorded income tax expenses of $0.8 million and $1.1 million in the three and six months ended September 30, 2016, respectively. As a result of purchase accounting for the acquired intangible assets in the ITC acquisition, the Company recorded a deferred tax liability of $1.1 million for the difference in book and tax basis. As a result, the Company was able to benefit additional deferred tax assets and therefore released a corresponding valuation allowance of $1.1 million during the three months ended September 30, 2017. Goodwill recognized in the acquisition is not deductible for tax purposes. Section 382 of the U.S. Internal Revenue Code of 1986, as amended (the “IRC”), provides limits on the extent to which a corporation that has undergone an ownership change (as defined in the IRC) can utilize any net operating loss ("NOL") and general business tax credit carryforwards it may have. The Company conducted a study as a result of the Company's May 2017 equity offering to determine whether Section 382 could limit the use of its carryforwards in this manner. After completing this study, the Company has concluded that the limitation will not have a material impact on its ability to utilize its NOL carryforwards. If there were material ownership changes subsequent to the study, such changes could limit the Company's ability to utilize its NOL carryforwards. The Company increased its NOL’s by $0.3 million due to acquired losses in the three months ended September 30, 2017 from ITC. Utilization of these losses by the Company will need further evaluation and may be subject to annual limitations under Section 382. Accounting for income taxes requires a two-step approach to recognizing and measuring uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if, based on the technical merits, it is more likely than not the position will be sustained upon audit, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely to be realized upon ultimate settlement. The Company re-evaluates these uncertain tax positions on a quarterly basis. The evaluation is based on factors including, but not limited to, changes in facts or circumstances, changes in tax law, effectively settled issues under audit and new audit activity. Any changes in these factors could result in the recognition of a tax benefit or an additional charge to the tax provision. The Company did not identify any uncertain tax positions in the six months ended September 30, 2017 and did not have any gross unrecognized tax benefits as of March 31, 2017.

Debt	6 Months Ended
Debt	Sep. 30, 2017
Debt Disclosure [Abstract]
Debt	Debt Senior Secured Term Loans On December 19, 2014, the Company entered into a second amendment to its Loan and Security Agreement with Hercules (the “Hercules Second Amendment”) and entered into a new term loan, borrowing an additional $1.5 million (the “Term Loan C”). After closing fees and expenses, the net proceeds to the Company for the Term Loan C were $1.4 million. The Company made interest only payments at an interest rate of 11% through March 16, 2017 when the interest rate was increased to 11.25%, until maturity on June 1, 2017, when Term Loan C was repaid in its entirety. Hercules received warrants to purchase 13,927 shares of common stock (the “First Warrant”) and 25,641 shares of common stock (the “Second Warrant”) in conjunction with prior term loans that have been repaid in full. Due to certain adjustment provisions within the warrants, they qualified for liability accounting. The fair value of the warrants, $0.4 million and $0.2 million, respectively, was recorded upon issuance to debt discount and a warrant liability. In conjunction with the Hercules Second Amendment, the First Warrant and Second Warrant were canceled and replaced with the issuance of a new warrant (the “Hercules Warrant”) to purchase 58,823 shares of common stock at an exercise price of $7.85 per share, subject to certain price-based and other anti-dilution adjustments. The Hercules Warrant expires on June 30, 2020. See Note 12, “Warrants and Derivative Liabilities”, for a discussion on the Hercules Warrant and the valuation assumptions used. Interest expense on the Term Loans for the three months ended September 30, 2017 and 2016, was less than $0.1 million. Included in both periods was less than $0.1 million of non-cash interest expense related to the amortization of the debt discount on the respective Term Loans. Interest expense on the Term Loans for the six months ended September 30, 2017 and 2016, was less than $0.1 million and $0.3 million, respectively. Included in both periods was less than $0.1 million of non-cash interest expense related to the amortization of debt discount on the respective Term Loans.

Warrants and Derivative Liabilities

6 Months Ended

Sep. 30, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Warrants and Derivative Liabilities

The Company accounts for its warrants and contingent consideration as liabilities due to certain adjustment provisions within the instruments, which require that they be recorded at fair value. The warrants are subject to revaluation at each balance sheet date and any change in fair value is recorded as a change in fair value of warrants until the earlier of its expiration or its exercise at which time the warrant liability will be reclassified to equity. The Company calculated the fair value of the warrants utilizing an integrated lattice model. The contingent consideration is subject to revaluation at each balance sheet date and any change in fair value is recorded as a change in fair value of contingent consideration until the earlier of its settlement or expiration. The Company determined the fair value of the contingent consideration utilizing a Black Scholes option pricing method. See Note 5, "Fair Value Measurements", for further discussion.

Senior Convertible Note Warrant

On April 4, 2012, the Company entered into a Purchase Agreement with Capital Ventures International ("CVI"). The Purchase Agreement included a warrant to purchase 309,406 shares of the Company’s common stock (the “Original Warrant”). Pursuant to an exchange in October 2013, the Original Warrant was exchanged for a new warrant (the “Exchanged Warrant”). The Exchanged Warrant expired on October 4, 2017.

Following is a summary of the key assumptions used to calculate the fair value of the Exchanged Warrant:



Fiscal Year 17	September 30, 2017	June 30, 2017
Risk-free interest rate	1.05%	1.05%
Expected annual dividend yield	—	—
Expected volatility	77.95%	78.25%
Term (years)	0.01	0.26
Fair value	$—	$—



Fiscal Year 16	March 31, 2017	December 31, 2016	September 30, 2016	June 30, 2016	March 31, 2016
Risk-free interest rate	0.91%	0.56%	0.59%	0.48%	0.66%
Expected annual dividend yield	—	—	—	—	—
Expected volatility	44.12%	58.04%	70.50%	76.30%	76.76%
Term (years)	0.51	0.76	1.01	1.26	1.51
Fair value	$—	$0.1 million	$0.2 million	$0.4 million	$0.4 million

The Company recorded no change in the fair value of the Exchanged Warrant during the three and six months ended September 30, 2017. The Company recorded net gains of $0.2 million resulting from a decrease in the fair value of the Exchanged Warrant in each of the three and six months ended September 30, 2016, respectively.

Hercules Warrant

On December 19, 2014, the Company entered into the Hercules Second Amendment. See Note 11, “Debt” for additional information. In conjunction with the agreement, the Company issued the Hercules Warrant to purchase 58,823 shares of the Company’s common stock. The Hercules Warrant is exercisable at any time after its issuance at an exercise price of $7.85 per share, subject to certain price-based and other anti-dilution adjustments, and expires on June 30, 2020.

Following is a summary of the key assumptions used to calculate the fair value of the Hercules Warrant:



Fiscal Year 17	September 30, 2017	June 30, 2017
Risk-free interest rate	1.56%	1.58%
Expected annual dividend yield	—	—
Expected volatility	63.97%	67.76%
Term (years)	2.72	2.97
Fair value	$0.1 million	$0.1 million



Fiscal Year 16	March 31, 2017	December 31, 2016	September 30, 2016	June 30, 2016	March 31, 2016
Risk-free interest rate	1.55%	1.57%	0.97%	0.86%	1.08%
Expected annual dividend yield	—	—	—	—	—
Expected volatility	66.51%	67.28%	67.98%	68.34%	70.25%
Term (years)	3.25	3.50	3.75	4.00	4.25
Fair value	$0.2 million	$0.2 million	$0.2 million	$0.3 million	$0.2 million

The Company recorded no change, and a net gain, resulting from a decrease of $0.1 million in the fair value of the Hercules Warrant during the three and six months ended September 30, 2017, respectively. The Company recorded a net loss and a net gain, resulting from an increase and a decrease in the fair value of the Hercules Warrant of less than $0.1 million during the three and six months ended September 30, 2016, respectively.

November 2014 Warrant

On November 13, 2014, the Company completed an offering of 909,090 units of the Company’s common stock with Hudson Bay Capital. Each unit consisted of one share of the Company’s common stock and 0.9 of a warrant to purchase one share of common stock, or a warrant to purchase in the aggregate 818,181 shares (the “November 2014 Warrant”). The November 2014 Warrant is exercisable at any time, at an exercise price equal to $7.81 per share, subject to certain price-based and other anti-dilution adjustments, and expires on November 13, 2019.

Following is a summary of the key assumptions used to calculate the fair value of the November 2014 Warrant:



Fiscal Year 17	September 30, 2017	June 30, 2017
Risk-free interest rate	1.49%	1.44%
Expected annual dividend yield	—	—
Expected volatility	65.64%	67.21%
Term (years)	2.12	2.37
Fair value	$0.8 million	$0.9 million



Fiscal Year 16	March 31, 2017	December 31, 2016	September 30, 2016	June 30, 2016	March 31, 2016
Risk-free interest rate	1.41%	1.43%	0.93%	0.77%	0.98%
Expected annual dividend yield	—	—	—	—	—
Expected volatility	66.53%	69.31%	68.96%	70.01%	69.88%
Term (years)	2.62	2.87	3.12	3.37	3.62
Fair value	$1.8 million	$2.3 million	$2.3 million	$3.2 million	$2.6 million

The Company recorded a net gain of $0.1 million and $1.0 million resulting from a decrease in the fair value of the November 2014 Warrant in the three and six months ended September 30, 2017, respectively. The Company recorded net gains, resulting from decreases in the fair value of the November 2014 Warrant of $0.9 million and $0.3 million in the three and six months ended September 30, 2016.

Contingent Consideration

The Company evaluated the ITC acquisition make whole payment set forth in the SPA (see Note 5, "Fair Value Measurements" for further details), which may require net settlement cash, and determined the contingent consideration qualified for liability classification and derivative treatment under ASC 815. As a result, for each period the fair value of the contingent consideration will be remeasured and the resulting gain or loss will be recognized in operating expenses until the liability is settled.

Following is a summary of the key assumptions used to calculate the fair value of the contingent consideration related to the ITC acquisition:



Fiscal Year 17	September 30, 2017	September 25, 2017
Risk-free interest rate	1.09%	1.09%
Expected annual dividend yield	—	—
Expected volatility	66.54%	65.71%
Term (years)	0.31	0.32
Fair value	$0.4 million	$0.6 million

The Company recorded a net gain of $0.2 million resulting from a decrease in the fair value of the contingent consideration in the three and six months ended September 30, 2017.

Stockholders' Equity	6 Months Ended
Stockholders' Equity	Sep. 30, 2017
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Equity Offerings On May 5, 2017, the Company entered into an underwriting agreement with Oppenheimer & Co. Inc., as representative of several underwriters named therein, relating to the issuance and sale (the "Offering") of 4.0 million shares of the Company's common stock at a public offering price of $4.00 per share. The net proceeds to the Company from the Offering were approximately $14.7 million, after deducting underwriting discounts and commissions and offering expenses payable by the Company. The Offering closed on May 10, 2017. In addition, the Company granted the underwriters a 30-day option (the “Option”) to purchase up to an additional 600,000 shares of common stock at the public offering price. On May 24, 2017, the underwriters notified the Company that they had exercised in full, their Option. The net proceeds to the Company from the Option were approximately $2.3 million, after deducting underwriting discounts and commissions and offering expenses payable by the Company. The total net proceeds to the Company from the Offering and the Option were approximately $17.0 million, after deducting underwriting discounts and commissions and offering expenses payable by the Company. The Option closed on May 26, 2017. ATM Arrangement On January 27, 2017, the Company entered into an At Market Issuance Sales Agreement ("ATM"), pursuant to which, the Company could, at its discretion, sell up to $10.0 million of the Company’s common stock through its sales agent, FBR Capital Markets & Co. ("FBR"). Sales of common stock made under the ATM were made pursuant to the prospectus supplement dated January 27, 2017, which supplements the prospectus dated October 1, 2014, included in the shelf registration statement that AMSC filed with the SEC on September 19, 2014. During the year ended March 31, 2017, the Company received net proceeds of $2.5 million, from sales of approximately 379,693 shares of its common stock at an average sales price of approximately $6.79 per share under the ATM. No sales of the Company's common stock were made under the ATM after March 31, 2017. On May 4, 2017, the Company provided to FBR a notice of termination of the ATM. Stock Purchase Agreement On September 25, 2017, the Company entered into the SPA with ITC. The purchase price was approximately $3.8 million, consisting of 884,890 AMSC Shares and $0.1 million in cash. See Note 4, “Acquisition and Related Goodwill” for further discussion.

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Contingencies From time to time, the Company is involved in legal and administrative proceedings and claims of various types. The Company records a liability in its consolidated financial statements for these matters when a loss is known or considered probable and the amount can be reasonably estimated. The Company reviews these estimates each accounting period as additional information is known and adjusts the loss provision when appropriate. If a matter is both probable to result in a liability and the amounts of loss can be reasonably estimated, the Company estimates and discloses the possible loss or range of loss to the extent necessary to make the consolidated financial statements not misleading. If the loss is not probable or cannot be reasonably estimated, a liability is not recorded in its consolidated financial statements. On September 13, 2011, the Company commenced a series of legal actions in China against Sinovel Wind Group Co. Ltd. (“Sinovel”). The Company’s Chinese subsidiary, Suzhou AMSC Superconductor Co. Ltd., filed a claim for arbitration with the Beijing Arbitration Commission in accordance with the terms of the Company’s supply contracts with Sinovel. The case is captioned (2011) Jing Zhong An Zi No. 963. The Company alleges that Sinovel committed various material breaches of its contracts with the Company and Sinovel has refused to pay past due amounts for prior shipments of core electrical components and spare parts. The Company is seeking compensation for past product shipments and retention (including interest) in the amount of approximately RMB 485 million (approximately $73 million) due to Sinovel’s breaches of its contracts. The Company is also seeking specific performance of its existing contracts as well as reimbursement of all costs and reasonable expenses with respect to the arbitration. The value of the undelivered components under the existing contracts, including the deliveries refused by Sinovel in March 2011, amounts to approximately RMB 4.6 billion (approximately $691 million). On October 8, 2011, Sinovel filed with the Beijing Arbitration Commission an application under the caption (2011) Jing Zhong An Zi No. 963, for a counterclaim against the Company for breach of the same contracts under which the Company filed its original arbitration claim. Sinovel claims, among other things, that the goods supplied by the Company do not conform to the standards specified in the contracts and claims damages in the amount of approximately RMB 1.2 billion (approximately $180 million) upon Sinovel’s requests for change of counterclaim. On February 27, 2012, Sinovel filed with the Beijing Arbitration Commission an application under the caption (2012) Jing Zhong An Zi No. 157, against the Company for breach of the same contracts under which the Company filed its original arbitration claim. Sinovel claims, among other things, that the goods supplied by the Company do not conform to the standards specified in the contracts and claims damages in the amount of approximately RMB 105 million (approximately $16 million). The Company believes that Sinovel’s claims are without merit and it intends to defend these actions vigorously. Since the proceedings in this matter are still in the early technical review phase, the Company cannot reasonably estimate possible losses or range of losses at this time. Other The Company enters into long-term construction contracts with customers that require the Company to obtain performance bonds. The Company is required to deposit an amount equivalent to some or all the face amount of the performance bonds into an escrow account until the termination of the bond. When the performance conditions are met, amounts deposited as collateral for the performance bonds are returned to the Company. In addition, the Company has various contractual arrangements in which minimum quantities of goods or services have been committed to be purchased on an annual basis. As of September 30, 2017, the Company had $0.2 million of restricted cash included in long-term assets. These amounts included in restricted cash primarily represent deposits to secure letters of credit for various supply contracts. These deposits are held in interest bearing accounts.

Restructuring

6 Months Ended

Sep. 30, 2017

Restructuring and Related Activities [Abstract]

Restructuring

The Company accounts for charges resulting from operational restructuring actions in accordance with ASC Topic 420, Exit or Disposal Cost Obligations (“ASC 420”) and ASC Topic 712, Compensation—Nonretirement Postemployment Benefits (“ASC 712”). In accounting for these obligations, the Company is required to make assumptions related to the amounts of employee severance, benefits, and related costs and the time period over which leased facilities will remain vacant, sublease terms, sublease rates and discount rates. Estimates and assumptions are based on the best information available at the time the obligation arises. These estimates are reviewed and revised as facts and circumstances dictate; changes in these estimates could have a material effect on the amount accrued on the consolidated balance sheet.

On April 3, 2017, the Board of Directors approved a plan to reduce the Company’s global workforce by approximately 8%, effective April 4, 2017. The purpose of the workforce reduction was to reduce operating expenses to better align with the Company’s current revenues. Included in the $1.3 million severance pay, charged to operations in the six months ended September 30, 2017, is $0.5 million of severance pay for one of the Company's former executive officers pursuant to the terms of a severance agreement dated June 30, 2017. Under the terms of the severance agreement, the Company's former executive officer is entitled to 18 months of his base salary, which is expected to be paid by December 31, 2018. From and after January 1, 2018, the Company, at its discretion, may settle any remaining unpaid cash severance owed to its former executive officer through the issuance of a number of immediately vested shares of the Company’s common stock, determined by multiplying the remaining unpaid cash severance owed by 120%, and then dividing by the closing stock price per share of the Company's common stock as of the last business day prior to the issuance of the shares.

All amounts related to these restructuring activities are expected to be paid by December 31, 2018.

The following table presents restructuring charges and cash payments for the six months ended September 30, 2017 (in thousands):



	Severance pay
	and benefits
Accrued restructuring balance at April 1, 2017	$	—
Charges to operations	1,328
Cash payments	(746		)
Accrued restructuring balance at September 30, 2017	$	582

All restructuring charges discussed above are included within restructuring in the Company’s unaudited condensed consolidated statements of operations. The Company includes $0.5 million of accrued restructuring within accounts payable and accrued expenses and the remaining $0.1 million long term portion is included within other liabilities in the Company's unaudited condensed consolidated balance sheets.

Business Segments

6 Months Ended

Sep. 30, 2017

Segment Reporting [Abstract]

Business Segments

The Company reports its financial results in two reportable business segments: Wind and Grid.

Through the Company’s Windtec Solutions, the Wind business segment enables manufacturers to field wind turbines with exceptional power output, reliability and affordability. The Company supplies advanced power electronics and control systems, licenses its highly engineered wind turbine designs, and provides extensive customer support services to wind turbine manufacturers. The Company’s design portfolio includes a broad range of drive trains and power ratings of 2 MWs and higher. The Company provides a broad range of power electronics and software-based control systems that are highly integrated and designed for optimized performance, efficiency, and grid compatibility.

Through the Company’s Gridtec Solutions, the Grid business segment enables electric utilities and renewable energy project developers to connect, transmit and distribute power with exceptional efficiency, reliability and affordability. The sales process is enabled by transmission planning services that allow it to identify power grid congestion, poor power quality and other risks, which helps the Company determine how its solutions can improve network performance. These services often lead to sales of grid interconnection solutions for wind farms and solar power plants, power quality systems, and transmission and distribution cable systems. The Company also sells ship protection products to the U.S. Navy through its Grid business segment.

The operating results for the two business segments are as follows (in thousands):



	Three months ended September 30,				Six months ended September 30,
	2017		2016		2017		2016
Revenues:
Wind	$	5,554	$	12,898	$	7,831	$	18,573
Grid	5,495		5,609		12,140		13,279
Total	$	11,049	$	18,507	$	19,971	$	31,852



	Three months ended September 30,						Six months ended September 30,
	2017			2016			2017			2016
Operating loss:
Wind	$	(1,440	)	$	(1,235	)	$	(5,873	)	$	(4,264	)
Grid	(6,100		)	(5,262		)	(14,268		)	(10,577		)
Unallocated corporate expenses	(265		)	(653		)	(2,358		)	(1,653		)
Total	$	(7,805	)	$	(7,150	)	$	(22,499	)	$	(16,494	)

The accounting policies of the business segments are the same as those for the consolidated Company. The Company’s business segments have been determined in accordance with the Company’s internal management structure, which is organized based on operating activities. The Company evaluates performance based upon several factors, of which the primary financial measures are segment revenues and segment operating loss. The disaggregated financial results of the segments reflect allocation of certain functional expense categories consistent with the basis and manner in which Company management internally disaggregates financial information for the purpose of assisting in making internal operating decisions. In addition, certain corporate expenses which the Company does not believe are specifically attributable or allocable to either of the two business segments have been excluded from the segment operating loss.

Unallocated corporate expenses primarily consist of stock-based compensation expense of $0.5 million and $0.7 million in the three months ended September 30, 2017 and 2016, respectively. Unallocated corporate expenses primarily consist of stock-based compensation expense of $1.2 million and $1.7 million in the six months ended September 30, 2017 and 2016, respectively. Additionally, a restructuring charge of $1.3 million is included in the six months ended September 30, 2017, as well as a gain for the change in fair value of the contingent consideration of $0.2 million in the three and six months ended September 30, 2017.

Total assets for the two business segments as of September 30, 2017 and March 31, 2017 are as follows (in thousands):



	September 30, 2017		March 31, 2017
Wind	$	17,328	$	18,346
Grid	30,052		31,060
Corporate assets	53,168		50,838
Total	$	100,548	$	100,244

The following table sets forth customers who represented 10% or more of the Company’s total revenues for the three and six months ended September 30, 2017 and 2016:



	Three months ended September 30,				Six months ended September 30,
	2017		2016		2017		2016
INOX Wind Limited	46	%	68	%	35	%	51	%
U.S. Navy	—	%	—	%	16	%	—	%
YMC Inc.	15	%	—	%	<10%		—	%

Recent Accounting Pronouncements

6 Months Ended

Sep. 30, 2017

New Accounting Pronouncements and Changes in Accounting Principles [Abstract]

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) and the International Accounting Standards Board ("IASB") issued, ASU 2014-09, Revenue from Contracts with Customers (Topic 606). The guidance substantially converges final standards on revenue recognition between the FASB and IASB providing a framework on addressing revenue recognition issues and, upon its effective date, replaces almost all existing revenue recognition guidance, including industry-specific guidance, in current U.S. generally accepted accounting principles. The FASB has subsequently issued the following amendments to ASU 2014-09 which are all effective for annual reporting periods beginning after December 15, 2017.


•	In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations, which clarifies the implementation guidance on principal versus agent considerations.


•	In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, which clarifies certain aspects of identifying performance obligations and licensing implementation guidance.


•	In May 2016, the FASB issued ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow- Scope Improvements and Practical Expedients related to disclosures of remaining performance obligations, as well as other amendments to guidance on collectability, non-cash consideration and the presentation of sales and other similar taxes collected from customers.

•

In December 2016, the FASB issued ASU No. 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which amends certain narrow aspects of the guidance issued in ASU 2014-09 including guidance related to the disclosure of remaining performance obligations and prior-period performance obligations, as well as other amendments to the guidance on loan guarantee fees, contract costs, refund liabilities, advertising costs and the clarification of certain examples.

The Company is currently evaluating the provisions of ASU 2014-09 and its amendments, and assessing the impact the adoption of this guidance will have on its financial position, results of operations and disclosures. This process has included analyzing the current contract portfolio, comparing the Company's current contract policies and accounting to the requirements of the new standard and identifying the differences. The Company anticipates the adoption of this guidance will result in certain changes in the identification of deliverables in its contracts and allocation of transaction price. The timing of revenue recognition could also be different than under the current guidance. These multiple element contracts are primarily entered into under the grid business unit. Additionally, this guidance could lead to recognizing certain revenue transactions sooner than in the past on certain contracts, as the Company will need to estimate the revenue it will be entitled to upon contract completion, and later on other contracts, due to lack of an enforceable right to payment for performance obligations satisfied over time. The Company will continue to assess its contracts for any other impacts that may result. During the second half of fiscal 2017 the Company plans to assess its current revenue controls, and identify and implement any changes that may be necessary to comply with its new revenue policies and the provisions of ASU 2014-09, which will be in place as of April 1, 2018.

The Company is required to adopt the new standards in the first quarter of fiscal 2018 and expects to do so retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the modified retrospective transition method). The Company is still evaluating the final impact of this adoption method on its consolidated financial statements.

In January 2016, the FASB issued ASU 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The amendments in ASU 2016-01 will enhance the reporting model for financial instruments to provide users of financial statements with more decision-useful information. This ASU is effective for annual reporting periods beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the impact, if any, the adoption of ASU 2016-01 may have on its consolidated financial statements.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The guidance in this ASU supersedes the leasing guidance in Topic 840, Leases. Under the new guidance, lessees are required to recognize lease assets and lease liabilities on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. The Company is currently evaluating the effects adoption of this guidance will have on its consolidated financial statements.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments in ASU 2016-13 will provide more decision useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The ASU is effective for annual reporting periods beginning after December 15, 2019, including interim periods within that year. The Company is currently evaluating the impact, if any, the adoption of ASU 2016-13 may have on its consolidated financial statements.

In 2016, the FASB issued the following two ASU's on Statement of Cash Flows (Topic 230). Both amendments are effective for annual reporting periods beginning after December 15, 2017, including interim periods within that year.


•	In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The amendments in ASU 2016-15 will provide more guidance towards the classification of multiple different types of cash flows in order to reduce the diversity in reporting across entities.

•

In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The amendments in ASU 2016-18 will explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows.

The Company is currently evaluating the impact, if any, the adoption of ASU 2016-15 and ASU 2016-18 may have on its consolidated financial statements.

In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. The amendments in ASU 2016-16 will improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The ASU is effective for annual reporting periods beginning after December 15, 2017, including interim periods within that year. The Company is currently evaluating the impact, if any, the adoption of ASU 2016-16 may have on its consolidated financial statements.

In January 2017, the FASB issued ASU 2017-01, Business Combinations. The amendments in ASU 2017-01 will clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The ASU is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those periods. The Company adopted ASU 2017-01 effective September 30, 2017, following the Acquisition of ITC. The Company considered these amendments in its decision to record the combination of the entities as an acquisition of a business. See Note 4, "Acquisition and Related Goodwill", for further details. These impacts have been included in the consolidated financial statements.

In January 2017, the FASB issued ASU 2017-03, Accounting Changes and Error Corrections (Topic 250) and Investments - Equity Method and Joint Ventures. The amendments in ASU 2017-03 provide additional detail surrounding disclosures required related to adoption of new pronouncements. The ASU is effective for the periods of each related pronouncement. The Company is currently evaluating the impact the adoption of ASU 2017-03 may have on its consolidated financial statements.

In January 2017, the FASB issued ASU 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. The amendments in ASU 2017-04 eliminated the prior requirement to perform procedures to determine the fair value at the impairment testing date of an entity's assets and liabilities (including unrecognized assets and liabilities) following the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. Under the new guidelines an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. The ASU is effective for annual reporting periods beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. Following the Acquisition of ITC, the Company performed an analysis and determined that the transaction included a portion of goodwill. The Company has accounted for that value on its balance sheet as of September 30, 2017. See Note 4, "Acquisition and Related Goodwill" for further details. The Company adopted ASU 2017-04 effective September 30, 2017, and determined there were no triggering events requiring further impairment analysis at this time. The Company expects to perform its annual impairment test during the fourth quarter of fiscal 2017.

In February 2017, the FASB issued ASU 2017-05, Other Income - Gains and Losses from the Derecognition of Non-financial Assets (Subtopic 610-20). The amendments in ASU 2017-05 clarify the scope of Subtopic 610-20, Other Income-Gains and Losses from the Derecognition of Non-financial Assets, and to add guidance for partial sales of non-financial assets. Subtopic 610-20, which was issued in May 2014 as a part of Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606), provides guidance for recognizing gains and losses from the transfer of non-financial assets in contracts with non-customers. The Company is currently evaluating the impact the adoption of ASU 2017-05 may have on its consolidated financial statements.

In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Subtopic 718) Scope of Modification Accounting. The amendments in ASU 2017-09 provide clarity and reduce both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation—Stock Compensation, to a change to the terms or conditions of a share-based payment award. The ASU is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those periods. The Company is currently evaluating the impact the adoption of ASU 2017-09 may have on its consolidated financial statements.

In July 2017, the FASB issued ASU 2017-11, Earnings per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), and Derivatives and Hedging (Topic 815). The amendments in ASU 2017-11 provide guidance for freestanding equity-linked financial instruments, such as warrants and conversion options in convertible debt or preferred stock, and should no longer be accounted for as a derivative liability at fair value as a result of the existence of a down round feature. The ASU is effective for annual reporting periods beginning after December 15, 2018, including interim periods within those periods. The Company is currently evaluating the impact the adoption of ASU 2017-11 may have on its consolidated financial statements.

Subsequent Events	6 Months Ended
Subsequent Events	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company has performed an evaluation of subsequent events through the time of filing this Quarterly Report on Form 10-Q with the SEC and has determined that there are no such events to report.

Nature of the Business and Operations and Liquidity (Policies)

6 Months Ended

Sep. 30, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of the Business and Operations

These unaudited condensed consolidated financial statements of the Company have been prepared on a going concern basis in accordance with United States generally accepted accounting principles (“GAAP”) and the Securities and Exchange Commission’s (“SEC”) instructions to Form 10-Q. The going concern basis of presentation assumes that the Company will continue operations and will be able to realize its assets and discharge its liabilities and commitments in the normal course of business. Certain information and footnote disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those instructions. The year-end condensed balance sheet data was derived from audited financial statements but does not include all disclosures required by GAAP. The unaudited condensed consolidated financial statements, in the opinion of management, reflect all adjustments (consisting of normal recurring adjustments) necessary for a fair statement of the results for the interim periods ended September 30, 2017 and 2016 and the financial position at September 30, 2017.

Goodwill

Recent Accounting Pronouncements


•	In March 2016, the FASB issued ASU No. 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations, which clarifies the implementation guidance on principal versus agent considerations.


•	In April 2016, the FASB issued ASU No. 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, which clarifies certain aspects of identifying performance obligations and licensing implementation guidance.


•	In May 2016, the FASB issued ASU No. 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow- Scope Improvements and Practical Expedients related to disclosures of remaining performance obligations, as well as other amendments to guidance on collectability, non-cash consideration and the presentation of sales and other similar taxes collected from customers.

•


•	In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. The amendments in ASU 2016-15 will provide more guidance towards the classification of multiple different types of cash flows in order to reduce the diversity in reporting across entities.

•

The Company is currently evaluating the impact, if any, the adoption of ASU 2016-15 and ASU 2016-18 may have on its consolidated financial statements.

Stock-Based Compensation (Tables)

6 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Stock-Based Compensation Expense



	Three months ended September 30,				Six months ended September 30,
	2017		2016		2017		2016
Cost of revenues	$	23	$	49	$	59	$	99
Research and development	61		62		110		92
Selling, general and administrative	394		542		1,063		1,462
Total	$	478	$	653	$	1,232	$	1,653

Schedule of Weighted Average Assumptions for Stock Options

These options will vest over 2 years. The weighted average assumptions used in the Black Scholes valuation model for stock options granted during the six months ended September 30, 2016 are as follows:.



	September 30, 2017	September 30, 2016		September 30, 2017	September 30, 2016
Expected volatility	N/A	67.6	%	N/A	67.6	%
Risk-free interest rate	N/A	1.3	%	N/A	1.3	%
Expected life (years)	N/A	5.7		N/A	5.7
Dividend yield	N/A	None		N/A	None

Computation of Net Loss per Common Share (Tables)

6 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Reconciliation of Numerators and Denominators of EPS Calculation



	Three months ended September 30,						Six months ended September 30,
	2017			2016			2017			2016
Numerator:
Net loss	$	(7,281	)	$	(7,325	)	$	(22,533	)	$	(17,680	)
Denominator:
Weighted-average shares of common stock outstanding	19,531			14,190			18,316			14,161
Weighted-average shares subject to repurchase	(471		)	(421		)	(391		)	(438		)
Shares used in per-share calculation ― basic	19,060			13,769			17,925			13,723
Shares used in per-share calculation ― diluted	19,060			13,769			17,925			13,723
Net loss per share ― basic	$	(0.38	)	$	(0.53	)	$	(1.26	)	$	(1.29	)
Net loss per share ― diluted	$	(0.38	)	$	(0.53	)	$	(1.26	)	$	(1.29	)

Acquisition and Related Goodwill (Tables)

6 Months Ended

Sep. 30, 2017

Business Combinations [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed



	September 25, 2017
Consideration
Cash	$	0.1
Equity (884,890 shares of common stock at $4.02 per share)	3.6
Contingent consideration	0.6
Total Consideration	$	4.3

Recognized amounts of identifiable assets acquired and liabilities assumed
Core technology and know-how	$	3.4
Working capital	0.2
Property, plant and equipment	0.0
Total identifiable net assets	$	3.6
Long-term deferred tax liability	1.1
Goodwill allocated	$	1.7

Fair Value Measurements (Tables)

6 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Carried at Fair Value on Recurring Basis

The following table provides the assets and liabilities carried at fair value on a recurring basis, measured as of September 30, 2017 and March 31, 2017 (in thousands):



	Total Carrying Value		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
September 30, 2017:
Assets:
Cash equivalents	$	24,392	$	24,392	$	—	$	—
Derivative liabilities:
Acquisition contingent consideration	$	370	$	—	$	—	$	370
Warrants	854		—		—		854
Total derivative liabilities	$	1,224	$	—	$	—	$	1,224



	Total Carrying Value		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
March 31, 2017:
Assets:
Cash equivalents	$	14,105	$	14,105	$	—	$	—
Derivative liabilities:
Warrants	$	1,923	$	—	$	—	$	1,923

Schedule of Liabilities Measured at Fair Value on Recurring Basis

The table below reflects the activity for the Company’s major classes of liabilities measured at fair value on a recurring basis (in thousands):



	Warrants			Acquisition Contingent Consideration
April 1, 2017	$	1,923		$	—
Issuance of contingent consideration	—			571
Mark to market adjustment	(1,069		)	(201		)
Balance at September 30, 2017	$	854		$	370



	Warrants
April 1, 2016	$	3,227
Mark to market adjustment	(1,304		)
Balance at March 31, 2017	$	1,923

Accounts Receivable (Tables)

6 Months Ended

Sep. 30, 2017

Receivables [Abstract]

Schedule of Accounts Receivable

Accounts receivable at September 30, 2017 and March 31, 2017 consisted of the following (in thousands):



	September 30, 2017			March 31, 2017
Accounts receivable (billed)	$	7,620		$	7,436
Accounts receivable (unbilled)	627			574
Less: Allowance for doubtful accounts	(54		)	(54		)
Accounts receivable, net	$	8,193		$	7,956

Inventory (Tables)

6 Months Ended

Sep. 30, 2017

Inventory Disclosure [Abstract]

Schedule of Inventory

Inventory at September 30, 2017 and March 31, 2017 consisted of the following (in thousands):



	September 30, 2017		March 31, 2017
Raw materials	$	5,776	$	4,263
Work-in-process	1,010		426
Finished goods	6,543		8,016
Deferred program costs	2,654		4,757
Net inventory	$	15,983	$	17,462

Property, Plant and Equipment (Tables)

6 Months Ended

Sep. 30, 2017

Property, Plant and Equipment [Abstract]

Schedule of Costs and Accumulated Depreciation of Plant and Equipment

The cost and accumulated depreciation of property and equipment at September 30, 2017 and March 31, 2017 are as follows (in thousands):



	September 30, 2017			March 31, 2017
Land	$	3,643		$	3,643
Construction in progress - equipment	606			601
Buildings	34,549			34,549
Equipment and software	73,798			73,445
Furniture and fixtures	1,154			1,201
Leasehold improvements	1,912			2,442
Property, plant and equipment, gross	115,662			115,881
Less accumulated depreciation	(79,224		)	(72,443		)
Property, plant and equipment, net	$	36,438		$	43,438

Accounts Payable and Accrued Expenses (Tables)

6 Months Ended

Sep. 30, 2017

Payables and Accruals [Abstract]

Schedule of Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses at September 30, 2017 and March 31, 2017 consisted of the following (in thousands):



	September 30, 2017		March 31, 2017
Accounts payable	$	4,089	$	3,207
Accrued inventories in-transit	86		313
Accrued other miscellaneous expenses	1,628		2,240
Accrued restructuring	493		—
Accrued compensation	3,674		5,042
Income taxes payable	2,194		1,344
Accrued warranty	1,852		2,344
Total	$	14,016	$	14,490

Schedule of Product Warranty Activity

Product warranty activity was as follows (in thousands):



	Three months ended September 30,						Six months ended September 30,
	2017			2016			2017			2016
Balance at beginning of period	$	2,026		$	2,774		$	2,344		$	3,601
Change in accruals for warranties during the period	86			316			127			417
Settlements during the period	(260		)	(396		)	(619		)	(1,324		)
Balance at end of period	$	1,852		$	2,694		$	1,852		$	2,694

Warrants and Derivative Liabilities (Tables)

6 Months Ended

Sep. 30, 2017

Exchanged Warrants

Class Of Warrant Or Right [Line Items]

Schedule of Assumptions Used to Calculate the Fair Value of Warrants

Following is a summary of the key assumptions used to calculate the fair value of the Exchanged Warrant:



Fiscal Year 17	September 30, 2017	June 30, 2017
Risk-free interest rate	1.05%	1.05%
Expected annual dividend yield	—	—
Expected volatility	77.95%	78.25%
Term (years)	0.01	0.26
Fair value	$—	$—



Fiscal Year 16	March 31, 2017	December 31, 2016	September 30, 2016	June 30, 2016	March 31, 2016
Risk-free interest rate	0.91%	0.56%	0.59%	0.48%	0.66%
Expected annual dividend yield	—	—	—	—	—
Expected volatility	44.12%	58.04%	70.50%	76.30%	76.76%
Term (years)	0.51	0.76	1.01	1.26	1.51
Fair value	$—	$0.1 million	$0.2 million	$0.4 million	$0.4 million

Hercules Warrants

Class Of Warrant Or Right [Line Items]

Schedule of Assumptions Used to Calculate the Fair Value of Warrants

Following is a summary of the key assumptions used to calculate the fair value of the Hercules Warrant:



Fiscal Year 17	September 30, 2017	June 30, 2017
Risk-free interest rate	1.56%	1.58%
Expected annual dividend yield	—	—
Expected volatility	63.97%	67.76%
Term (years)	2.72	2.97
Fair value	$0.1 million	$0.1 million



Fiscal Year 16	March 31, 2017	December 31, 2016	September 30, 2016	June 30, 2016	March 31, 2016
Risk-free interest rate	1.55%	1.57%	0.97%	0.86%	1.08%
Expected annual dividend yield	—	—	—	—	—
Expected volatility	66.51%	67.28%	67.98%	68.34%	70.25%
Term (years)	3.25	3.50	3.75	4.00	4.25
Fair value	$0.2 million	$0.2 million	$0.2 million	$0.3 million	$0.2 million

November 2014 Warrant

Class Of Warrant Or Right [Line Items]

Schedule of Assumptions Used to Calculate the Fair Value of Warrants

Following is a summary of the key assumptions used to calculate the fair value of the November 2014 Warrant:



Fiscal Year 17	September 30, 2017	June 30, 2017
Risk-free interest rate	1.49%	1.44%
Expected annual dividend yield	—	—
Expected volatility	65.64%	67.21%
Term (years)	2.12	2.37
Fair value	$0.8 million	$0.9 million



Fiscal Year 16	March 31, 2017	December 31, 2016	September 30, 2016	June 30, 2016	March 31, 2016
Risk-free interest rate	1.41%	1.43%	0.93%	0.77%	0.98%
Expected annual dividend yield	—	—	—	—	—
Expected volatility	66.53%	69.31%	68.96%	70.01%	69.88%
Term (years)	2.62	2.87	3.12	3.37	3.62
Fair value	$1.8 million	$2.3 million	$2.3 million	$3.2 million	$2.6 million

Acquisition contingent consideration

Class Of Warrant Or Right [Line Items]

Schedule of Assumptions Used to Calculate the Fair Value of Warrants

Following is a summary of the key assumptions used to calculate the fair value of the contingent consideration related to the ITC acquisition:



Fiscal Year 17	September 30, 2017	September 25, 2017
Risk-free interest rate	1.09%	1.09%
Expected annual dividend yield	—	—
Expected volatility	66.54%	65.71%
Term (years)	0.31	0.32
Fair value	$0.4 million	$0.6 million

- Definition

Tabular disclosure of the application of the fair value option for measurement and reporting of eligible financial assets and liabilities (as defined), as well as certain other eligible items (as defined) included in the statement of financial position, whether such option is elected for a single eligible item or a group of similar eligible items and is in addition to other disclosures concerning fair value which the company may be required to provide. Such disclosure might be expected to include: (1) for items included in the statement of financial position: (a) for each line item in the statement of financial position that includes an item or items for which the fair value option has been elected, provide the aggregate carrying amount of ineligible items included in each line item in the balance sheet, if any; (b) the difference between the aggregate fair value and the aggregate unpaid principal balance (assuming contractual principal amounts and fair value option elected) of: (i) loans and long-term receivables (other than securities otherwise reported at fair value) and (ii) long-term debt instruments; (c) for loans held as assets for which the fair value option has been elected: (i) the aggregate fair value of loans that are 90 days or more past due, (ii) if the policy is to recognize interest income separately from other changes in fair value, the aggregate fair value of loans in nonaccrual status, and (iii) the difference between the aggregate fair value and the aggregate unpaid principal balance for loans that are 90 days or more past due, in nonaccrual status, or both; (2) for items included in the income statement: (a) the amounts of gains and losses from fair value changes included in earnings and in which line in the income statement those gains and losses are reported whether or not combined with gains and losses from items required to be accounted for at fair value; (b) for loans and other receivables held as assets, the estimated amount of gains or losses included in earnings attributable to changes in instrument-specific credit risk; (c) for liabilities with fair values that have been significantly affected during the reporting period by changes in the instrument-specific credit risk, the estimated amount of gains and losses from fair value changes included in earnings that are attributable to changes in the instrument-specific credit risk; and (3) certain other disclosures as required or determined to be provided.

+ References + Details

Restructuring (Tables)

6 Months Ended

Sep. 30, 2017

Restructuring and Related Activities [Abstract]

Restructuring Costs

The following table presents restructuring charges and cash payments for the six months ended September 30, 2017 (in thousands):



	Severance pay
	and benefits
Accrued restructuring balance at April 1, 2017	$	—
Charges to operations	1,328
Cash payments	(746		)
Accrued restructuring balance at September 30, 2017	$	582

Business Segments (Tables)

6 Months Ended

Sep. 30, 2017

Segment Reporting [Abstract]

Schedule of Operating Results for Business Segments

The operating results for the two business segments are as follows (in thousands):



	Three months ended September 30,				Six months ended September 30,
	2017		2016		2017		2016
Revenues:
Wind	$	5,554	$	12,898	$	7,831	$	18,573
Grid	5,495		5,609		12,140		13,279
Total	$	11,049	$	18,507	$	19,971	$	31,852



	Three months ended September 30,						Six months ended September 30,
	2017			2016			2017			2016
Operating loss:
Wind	$	(1,440	)	$	(1,235	)	$	(5,873	)	$	(4,264	)
Grid	(6,100		)	(5,262		)	(14,268		)	(10,577		)
Unallocated corporate expenses	(265		)	(653		)	(2,358		)	(1,653		)
Total	$	(7,805	)	$	(7,150	)	$	(22,499	)	$	(16,494	)

Schedule of Total Assets for Segments

Total assets for the two business segments as of September 30, 2017 and March 31, 2017 are as follows (in thousands):



	September 30, 2017		March 31, 2017
Wind	$	17,328	$	18,346
Grid	30,052		31,060
Corporate assets	53,168		50,838
Total	$	100,548	$	100,244

Schedule of Revenues by Major Customers

The following table sets forth customers who represented 10% or more of the Company’s total revenues for the three and six months ended September 30, 2017 and 2016:



	Three months ended September 30,				Six months ended September 30,
	2017		2016		2017		2016
INOX Wind Limited	46	%	68	%	35	%	51	%
U.S. Navy	—	%	—	%	16	%	—	%
YMC Inc.	15	%	—	%	<10%		—	%

Nature of the Business and Operations and Liquidity - Additional Information (Detail) $ in Thousands			1 Months Ended	3 Months Ended		6 Months Ended		66 Months Ended
	May 26, 2017 USD ($)	May 10, 2017 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2017 USD ($) employee	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) employee	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) employee	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Description Of Business [Line Items]
Accumulated deficit				$ 978,090		$ 978,090		$ 978,090	$ 955,557
Cash and cash equivalents				30,320	$ 25,262	30,320	$ 25,262	$ 30,320	$ 26,784	$ 39,330
Net cash used in operating activities						13,539	10,912
Restructuring charges				$ (12)	$ 0	$ 1,328	0
Number of workforce persons \| employee				321		321		321
Cash flows from financing activities						$ 15,188	$ (2,490)	$ 85,100
Proceeds from additional equity offering	$ 17,000	$ 17,000
INOX Wind Limited
Description Of Business [Line Items]
Strategic agreements value			$ 210,000
Manufacturing agreement period, additional period required			3 years

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 478	$ 653	$ 1,232	$ 1,653
Cost of revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	23	49	59	99
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	61	62	110	92
Selling, general and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 394	$ 542	$ 1,063	$ 1,462

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Immediately vested common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)			37,140	35,000
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)			795,500	126,000
Unrecognized compensation cost for unvested employee stock-based compensation awards outstanding, net of forfeitures	$ 3.6		$ 3.6
Weighted-average period over which unrecognized compensation expense is expected to be recognized			2 years 20 days
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)			16,667
Vesting period			8 days
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				2 years
Unrecognized compensation cost for unvested employee stock-based compensation awards outstanding, net of forfeitures	$ 0.3		$ 0.3
Weighted-average period over which unrecognized compensation expense is expected to be recognized			1 year 6 months
Options granted in period (in shares)	0	9,703	0	9,703
Minimum \| Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			2 years	2 years
Maximum \| Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years	3 years

Stock-Based Compensation - Assumptions (Details) - Stock options	6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	67.60%	67.60%
Risk-free interest rate	1.30%	1.30%
Expected life (years)	5 years 8 months 12 days	5 years 8 months 12 days
Dividend yield	0.00%	0.00%

Computation of Net Loss per Common Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted EPS (in shares)	1.5	1.6	1.5	1.6
Stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted EPS (in shares)	0.3	0.4	0.3	0.4
Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted EPS (in shares)	1.2	1.2	1.2	1.2

Computation of Net Loss per Common Share - Reconciliation of Numerators and Denominators of EPS Calculation (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator:
Net loss	$ (7,281)	$ (7,325)	$ (22,533)	$ (17,680)
Denominator:
Weighted-average shares of common stock outstanding (in shares)	19,531	14,190	18,316	14,161
Weighted-average shares subject to repurchase (in shares)	(471)	(421)	(391)	(438)
Shares used in per-share calculation ― basic (in shares)	19,060	13,769	17,925	13,723
Shares used in per-share calculation ― diluted (in shares)	19,060	13,769	17,925	13,723
Net loss per share ― basic (in dollars per share)	$ (0.38)	$ (0.53)	$ (1.26)	$ (1.29)
Net loss per share ― diluted (in dollars per share)	$ (0.38)	$ (0.53)	$ (1.26)	$ (1.29)

Acquisitions and Related Goodwill - Additional Information (Details) - USD ($)	Sep. 25, 2017	Sep. 30, 2017	Mar. 31, 2017
Business Acquisition [Line Items]
Goodwill allocated		$ 1,711,000	$ 0
Infinia Technology Corporation (ITC)
Business Acquisition [Line Items]
Consideration transferred, excluding contingent consideration	$ 3,800,000
Business combination, cash paid	$ 100,000
Business combination, stock issued (in shares)	884,890
Par value per share (in dollars per share)	$ 0.01
Fair value per acquiree share (in dollars per share)	$ 4.02
Resale registration statement, filing period, minimum	10 days
Period for Make Whole Payment	90 days
Issuance of contingent consideration	$ 600,000
Intangible assets assumed	3,400,000
Working capital	200,000
Deferred tax liabilities	1,100,000
Business combination, fair value	4,200,000
Acquisition cost expensed (less than)	100,000
Goodwill allocated	$ 1,700,000

Acquisitions and Related Goodwill Acquisition and Related Goodwill (Details) - USD ($)		6 Months Ended
	Sep. 25, 2017	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2017
Consideration
Equity (884,890 shares of common stock at $4.02 per share)		$ 3,557,000	$ 0
Recognized amounts of identifiable assets acquired and liabilities assumed
Goodwill allocated		$ 1,711,000		$ 0
Infinia Technology Corporation (ITC)
Consideration
Cash	$ 100,000
Equity (884,890 shares of common stock at $4.02 per share)	3,600,000
Contingent consideration	600,000
Total Consideration	4,300,000
Recognized amounts of identifiable assets acquired and liabilities assumed
Core technology and know-how	3,400,000
Working capital	200,000
Property, plant and equipment (less than)	0
Total identifiable net assets	3,600,000
Long-term deferred tax liability	1,100,000
Goodwill allocated	$ 1,700,000

Fair Value Measurements - Schedule of Assets and Liabilities Carried at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017	Mar. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 24,392	$ 14,105
Warrants	1,224	1,923
Reported value measurement \| Quoted Prices in Active Markets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	24,392	14,105
Warrants	0	0
Reported value measurement \| Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Warrants	0	0
Reported value measurement \| Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Warrants	1,224	1,923
Acquisition contingent consideration
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants	370	0
Acquisition contingent consideration \| Reported value measurement \| Quoted Prices in Active Markets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants	0
Acquisition contingent consideration \| Reported value measurement \| Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants	0
Acquisition contingent consideration \| Reported value measurement \| Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants	370
Warrants
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants	854	$ 1,923	$ 3,227
Warrants \| Reported value measurement \| Quoted Prices in Active Markets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants	0
Warrants \| Reported value measurement \| Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants	0
Warrants \| Reported value measurement \| Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants	$ 854

Fair Value Measurements - Schedule of Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 1,923
Ending balance	1,224	$ 1,923
Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	1,923	3,227
Issuance of contingent consideration	0
Mark to market adjustment	(1,069)	(1,304)
Ending balance	854	1,923
Acquisition contingent consideration
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0
Issuance of contingent consideration	571
Mark to market adjustment	(201)
Ending balance	$ 370	$ 0

Accounts Receivable - Schedule of Accounts Receivable (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017
Receivables [Abstract]
Accounts receivable (billed)	$ 7,620	$ 7,436
Accounts receivable (unbilled)	627	574
Less: Allowance for doubtful accounts	(54)	(54)
Accounts receivable, net	$ 8,193	$ 7,956

Inventory - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 5,776	$ 4,263
Work-in-process	1,010	426
Finished goods	6,543	8,016
Deferred program costs	2,654	4,757
Net inventory	$ 15,983	$ 17,462

Inventory - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Inventory Disclosure [Abstract]
Inventory write-down	$ 100	$ 400	$ 351	$ 671

Property, Plant and Equipment - Schedule of Costs and Accumulated Depreciation (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 115,662	$ 115,881
Less accumulated depreciation	(79,224)	(72,443)
Property, plant and equipment, net	36,438	43,438
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,643	3,643
Construction in progress - equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	606	601
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	34,549	34,549
Equipment and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	73,798	73,445
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,154	1,201
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,912	$ 2,442

Property, Plant and Equipment - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 3.2	$ 1.7	$ 7.5	$ 3.5
Change inrevised estimate of remaining useful lives \| Cost of goods sold
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 1.6		$ 4.1

Accounts Payable and Accrued Expenses - Schedule of Accounts Payable and Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016
Payables and Accruals [Abstract]
Accounts payable	$ 4,089		$ 3,207
Accrued inventories in-transit	86		313
Accrued other miscellaneous expenses	1,628		2,240
Accrued restructuring	493		0
Accrued compensation	3,674		5,042
Income taxes payable	2,194		1,344
Accrued warranty	1,852	$ 2,026	2,344	$ 2,694	$ 2,774	$ 3,601
Total	$ 14,016		$ 14,490

Accounts Payable and Accrued Expenses - Additional Information (Detail)	6 Months Ended
	Sep. 30, 2017
Minimum
Product Warranty Liability [Line Items]
Warranty period	1 year
Maximum
Product Warranty Liability [Line Items]
Warranty period	3 years

Accounts Payable and Accrued Expenses - Schedule of Product Warranty Activity (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Movement in Extended Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 2,026	$ 2,774	$ 2,344	$ 3,601
Change in accruals for warranties during the period	86	316	127	417
Settlements during the period	(260)	(396)	(619)	(1,324)
Balance at end of period	$ 1,852	$ 2,694	$ 1,852	$ 2,694

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 25, 2017
Income Tax Contingency [Line Items]
Income tax (benefit) expense	$ (171)	$ 794	$ (71)	$ 1,117
Release of valuation allowance	1,100
Infinia Technology Corporation (ITC)
Income Tax Contingency [Line Items]
Long-term deferred tax liability					$ 1,100
Infinia Technology Corporation (ITC)
Income Tax Contingency [Line Items]
Acquired losses	$ 300		$ 300

Debt - Additional Information (Detail) - Senior secured loan - USD ($)		3 Months Ended		6 Months Ended
	Dec. 19, 2014	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 17, 2017	Mar. 16, 2017
FIrst Warrants \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	13,927
Fair value of warrants issued	$ 400,000
Second Warrants \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	25,641
Fair value of warrants issued	$ 200,000
Hercules Warrants \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	58,823
Warrant exercise price (in dollars per share)	$ 7.85	$ 7.85		$ 7.85
Term Loan
Debt Instrument [Line Items]
Interest expense, debt (less than)		$ 100,000	$ 100,000	$ 100,000	$ 300,000
Non-cash interest expense amortization of debt discount (less than)		$ 100,000	$ 100,000	$ 100,000	$ 100,000
Term Loan C \| Hercules Technology Growth Capital
Debt Instrument [Line Items]
Debt, face amount	$ 1,500,000.0
Net proceeds from debt	$ 1,400,000
Interest rate, stated percentage						11.25%	11.00%
Debt instrument, maturity date				Jun. 01, 2017

Warrants and Derivative Liabilities - Additional Information (Detail) - USD ($)			3 Months Ended		6 Months Ended
	Dec. 19, 2014	Apr. 04, 2012	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Nov. 13, 2014
Derivative [Line Items]
Change in fair value of warrants and contingent consideration			$ (144,000)	$ (1,244,000)	$ (1,069,000)	$ (567,000)
Hercules Warrants
Derivative [Line Items]
Change in fair value of warrants and contingent consideration			0	(100,000)	(100,000)	100,000
November 2014 Warrant
Derivative [Line Items]
Change in fair value of warrants and contingent consideration			(100,000)	(900,000)	$ (1,000,000)	(300,000)
Warrants expiration date					Nov. 13, 2019
Common stock units offered (in shares)							909,090
Warrants to purchase one share of common stock (in shares)							0.9
Number of warrants issued to purchase common stock (in shares)							818,181
Sale of stock, price per share (in dollars per share)							$ 7.81
Acquisition contingent consideration
Derivative [Line Items]
Change in fair value of warrants and contingent consideration			(200,000)		$ (200,000)
Capital Ventures International \| Exchanged Warrants
Derivative [Line Items]
Change in fair value of warrants and contingent consideration			$ 0	$ (200,000)	$ 0	$ (200,000)
Senior convertible note warrant \| Capital Ventures International \| Original Warrants
Derivative [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)		309,406
Senior secured loan \| Hercules Technology Growth Capital \| Hercules Warrants
Derivative [Line Items]
Number of shares received from warrants received to purchase common stock (in shares)	58,823
Warrant exercise price (in dollars per share)	$ 7.85		$ 7.85		$ 7.85
Warrants expiration date					Jun. 30, 2020

Warrants and Derivative Liabilities - Schedule of Assumptions Used to Calculate the Fair Value of Exchanged Warrants (Detail) - USD ($) $ in Millions			3 Months Ended
	Sep. 30, 2017	Sep. 25, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016
Exchanged Warrants
Derivative [Line Items]
Risk-free interest rate			1.05%	1.05%	0.91%	0.56%	0.59%	0.48%	0.66%
Expected annual dividend yield			0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Expected volatility			77.95%	78.25%	44.12%	58.04%	70.50%	76.30%	76.76%
Term			4 days	3 months 4 days	6 months 4 days	9 months 4 days	1 year 4 days	1 year 3 months 4 days	1 year 6 months 4 days
Fair value			$ 0.0	$ 0.0	$ 0.0	$ 0.1	$ 0.2	$ 0.4	$ 0.4
Hercules Warrants
Derivative [Line Items]
Risk-free interest rate			1.56%	1.58%	1.55%	1.57%	0.97%	0.86%	1.08%
Expected annual dividend yield			0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Expected volatility			63.97%	67.76%	66.51%	67.28%	67.98%	68.34%	70.25%
Term			2 years 8 months 20 days	2 years 11 months 20 days	3 years 3 months	3 years 6 months	3 years 9 months	4 years	4 years 3 months
Fair value			$ 0.1	$ 0.1	$ 0.2	$ 0.2	$ 0.2	$ 0.3	$ 0.2
November 2014 Warrant
Derivative [Line Items]
Risk-free interest rate			1.49%	1.44%	1.41%	1.43%	0.93%	0.77%	0.98%
Expected annual dividend yield			0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Expected volatility			65.64%	67.21%	66.53%	69.31%	68.96%	70.01%	69.88%
Term			2 years 1 month 13 days	2 years 4 months 13 days	2 years 7 months 13 days	2 years 10 months 13 days	3 years 1 month 13 days	3 years 4 months 13 days	3 years 7 months 13 days
Fair value			$ 0.8	$ 0.9	$ 1.8	$ 2.3	$ 2.3	$ 3.2	$ 2.6
Acquisition contingent consideration
Derivative [Line Items]
Risk-free interest rate	1.09%	1.09%
Expected annual dividend yield	0.00%	0.00%
Expected volatility	66.54%	65.71%
Term	3 months 22 days	3 months 27 days
Fair value	$ 0.4	$ 0.6

Stockholders' Equity - Additional Information (Detail) - USD ($)					12 Months Ended
	Sep. 25, 2017	May 26, 2017	May 24, 2017	May 10, 2017	Mar. 31, 2017	Jan. 27, 2017
Class of Stock [Line Items]
Proceeds from additional equity offering		$ 17,000,000		$ 17,000,000
Public stock offering
Class of Stock [Line Items]
Common stock, shares issued (in shares)				4,000,000
Sale of stock, price per share (in dollars per share)				$ 4.00
Proceeds from additional equity offering				$ 14,700,000
Over-allotment option
Class of Stock [Line Items]
Common stock, shares issued (in shares)				600,000
Proceeds from additional equity offering			$ 2,300,000
Over allotment common stock options period (in shares)				30 days
ATM issuance sales agreement
Class of Stock [Line Items]
Sale of stock, price per share (in dollars per share)					$ 6.79
Maximum value of shares for sale						$ 10,000,000.0
Proceeds from issuance ATM offering					$ 2,500,000
Number of shares issued (in shares)					379,693
Infinia Technology Corporation (ITC)
Class of Stock [Line Items]
Consideration transferred, excluding contingent consideration	$ 3,800,000
Business combination, stock issued (in shares)	884,890
Business combination, cash paid	$ 100,000

Commitments and Contingencies - Additional Information (Detail) $ in Thousands, ¥ in Millions								1 Months Ended		3 Months Ended		6 Months Ended
	Sep. 25, 2017 USD ($)	Feb. 27, 2012 USD ($)	Feb. 27, 2012 CNY (¥)	Oct. 08, 2011 USD ($)	Oct. 08, 2011 CNY (¥)	Sep. 13, 2011 USD ($)	Sep. 13, 2011 CNY (¥)	Mar. 31, 2011 USD ($)	Mar. 31, 2011 CNY (¥)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Mar. 31, 2017 USD ($)
Commitments And Contingencies [Line Items]
Restricted cash included in long-term assets										$ 165		$ 165		$ 165
Gain on sale of minority interest										951	$ 0	951	$ 0
Derivative liabilities										1,224		1,224		1,923
Sinovel Wind Group Co. Ltd.
Commitments And Contingencies [Line Items]
Sought compensation amount		$ 16,000	¥ 105	$ 180,000	¥ 1,200	$ 73,000	¥ 485
Value of the undelivered components								$ 691,000	¥ 4,600
Infinia Technology Corporation (ITC)
Commitments And Contingencies [Line Items]
Consideration transferred, excluding contingent consideration	$ 3,800
Business combination, cash paid	$ 100
Acquisition contingent consideration
Commitments And Contingencies [Line Items]
Derivative liabilities										370		370		$ 0
Acquisition contingent consideration \| Infinia Technology Corporation (ITC)
Commitments And Contingencies [Line Items]
Derivative liabilities										$ 400		$ 400

Restructuring - Schedule of Charges and Payments (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Apr. 04, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]
Number of positions eliminated, period percent	8.00%
Restructuring Reserve [Roll Forward]
Charges to operations		$ (12)	$ 0	$ 1,328	$ 0
Accrued restructuring		493		493		$ 0
Severance pay and benefits
Restructuring Reserve [Roll Forward]
Accrued restructuring balance at April 1, 2017				0
Charges to operations				1,328
Cash payments				(746)
Accrued restructuring balance at September 30, 2017		582		$ 582
Former executive officer \| Severance pay and benefits
Restructuring Cost and Reserve [Line Items]
Period of post employment salary	18 months
Share multiplier, unpaid cash owed percentage				120.00%
Restructuring Reserve [Roll Forward]
Charges to operations				$ 500
Accounts payable and accrued expenses \| Severance pay and benefits
Restructuring Reserve [Roll Forward]
Accrued restructuring		500		500
Other liabilities \| Severance pay and benefits
Restructuring Reserve [Roll Forward]
Restructuring reserve, noncurrent		$ 100		$ 100

Business Segments - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment MW	Sep. 30, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of reportable business segments \| segment			2
Stock-based compensation expense	$ 478	$ 653	$ 1,232	$ 1,653
Restructuring charges	(12)	0	1,328	0
Change in fair value of contingent consideration	201	0	$ 201	0
Minimum
Segment Reporting Information [Line Items]
Megawatts of drive trains and power ratings \| MW			2
Unallocated corporate expenses
Segment Reporting Information [Line Items]
Stock-based compensation expense	$ 500	$ 700	$ 1,200	$ 1,700
Restructuring charges			$ 1,300

Business Segments - Operating Results for Two Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Revenues	$ 11,049	$ 18,507	$ 19,971	$ 31,852
Operating loss	(7,805)	(7,150)	(22,499)	(16,494)
Unallocated corporate expenses
Segment Reporting Information [Line Items]
Operating loss	(265)	(653)	(2,358)	(1,653)
Wind
Segment Reporting Information [Line Items]
Revenues	5,554	12,898	7,831	18,573
Wind \| Operating Segments
Segment Reporting Information [Line Items]
Operating loss	(1,440)	(1,235)	(5,873)	(4,264)
Grid
Segment Reporting Information [Line Items]
Revenues	5,495	5,609	12,140	13,279
Grid \| Operating Segments
Segment Reporting Information [Line Items]
Operating loss	$ (6,100)	$ (5,262)	$ (14,268)	$ (10,577)

Business Segments - Total Business Segments Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	$ 100,548	$ 100,244
Operating Segments \| Wind
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	17,328	18,346
Operating Segments \| Grid
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	30,052	31,060
Corporate assets
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	$ 53,168	$ 50,838

Business Segments - Schedule of Revenues by Major Customers (Detail) - Total revenue - Customer concentration risk	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
INOX Wind Limited
Segment Reporting Asset Reconciling Item [Line Items]
Concentration risk, revenue (less than 10% for YMC Inc. for the six months ended September 2017)	46.00%	68.00%	35.00%	51.00%
Navy Surface Warfare Center Carderock [Member]
Segment Reporting Asset Reconciling Item [Line Items]
Concentration risk, revenue (less than 10% for YMC Inc. for the six months ended September 2017)	0.00%	0.00%	16.00%	0.00%
YMC, Inc.
Segment Reporting Asset Reconciling Item [Line Items]
Concentration risk, revenue (less than 10% for YMC Inc. for the six months ended September 2017)	15.00%	0.00%		0.00%

Unaudited Condensed Consolidated Balance Sheets (Parenthetical) $ in Thousands	Mar. 31, 2017 USD ($)
Statement of Financial Position [Abstract]
Note payable, unamortized discount, current	$ 19