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Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Mar. 31, 2017 | Mar. 31, 2016 | Mar. 31, 2015 | Apr. 01, 2017
Deferred tax assets | $ 407 | $ 96 |  |
Valuation allowance | 315,092 | 301,393 |  |
Increase in valuation allowance | 13,700 |  |  |
Deferred tax asset reflecting the benefit of deductions from the exercise of stock options | 13,000 |  |  |
Undistributed earnings available for repatriation | 2,100 |  |  |
Reversal of uncertain tax positions | 0 | $ 0 | $ 1,100 |
Austria |  |  |  |
Net operating loss carryforwards | 37,100 |  |  |
China |  |  |  |
Net operating loss carryforwards | $ 17,900 |  |  |
Net operating loss carryforward period | 5 years |  |  |
Statute of limitations for audit, period | 3 years |  |  |
Federal |  |  |  |
Net operating loss carryforwards | $ 798,000 |  |  |
Research and development and other tax credit carryforwards | 9,500 |  |  |
State |  |  |  |
Net operating loss carryforwards | 143,000 |  |  |
Research and development and other tax credit carryforwards | 3,200 |  |  |
Foreign earnings repatriated |  |  |  |
Federal and state deferred tax liability | 700 |  |  |
Power Quality Systems, Inc. |  |  |  |
Net operating loss carryforwards | $ 3,700 |  |  |
Accounting Standards Update 2016-09 |  |  |  |
Deferred tax assets |  |  |  | $ 18,000
Valuation allowance |  |  |  | $ 18,000

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