Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Deferred tax asset reflecting the benefit of deductions from the exercise of stock options	$ 13,000,000
Excess tax deductions from stock option exercised	$ 52,500,000
Stock options exercised dates	March 31, 2006 through 2016
Undistributed earnings available for repatriation	$ 1,200,000
Uncertain tax positions	0
Unrecognized tax benefits that, if recognized, would result in a reduction of the Company's effective tax rate	0	$ 0
Austria
Net operating loss carryforwards	$ 42,600,000
China
Operating loss carryforwards expiration years	Dec. 31, 2016
Net operating loss carryforwards	$ 32,000,000
Net operating loss carryforward period	5 years
China \| Earliest Tax Year
Income tax year under examination	2013
China \| Latest Tax Year
Income tax year under examination	2014
Romania
Operating loss carryforwards expiration years	Mar. 31, 2023
Net operating loss carryforwards	$ 500,000
Federal
Net operating loss carryforwards	791,000,000
Research and development and other tax credit carryforwards	9,300,000
State
Net operating loss carryforwards	177,000,000
Research and development and other tax credit carryforwards	2,900,000
Foreign Earnings Repatriated
Federal and state deferred tax liability	400,000
Power Quality Systems, Inc.
Net operating loss carryforwards	$ 3,700,000
Maximum
Operating loss carryforwards expiration years	Mar. 31, 2036
Expiration of other tax credit carryforwards	Mar. 31, 2036
Maximum \| Austria
Open tax year	2016
Maximum \| China
Open tax year	2012
Maximum \| Romania
Open tax year	2016
Maximum \| U.S
Open tax year	2016
Minimum
Operating loss carryforwards expiration years	Mar. 31, 2017
Expiration of other tax credit carryforwards	Mar. 31, 2017
Minimum \| Austria
Open tax year	2012
Minimum \| China
Open tax year	2008
Minimum \| Romania
Open tax year	2014
Minimum \| U.S
Open tax year	1995

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