Stock-Based Compensation - Stock Option Activity under All Plans and Other Grants (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Sep. 30, 2014	Mar. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding, Beginning Balance	851,165
Number of Shares, Granted	400,000	158,000
Number of Shares, Exercised	(88,833)
Number of Shares, Canceled or expired	(10,332)
Number of Shares, Outstanding, Ending Balance	1,152,000	851,165
Number of Shares, Options exercisable at September 30, 2014	527,000
Number of Shares, Unvested options expected to become exercisable after September 30, 2014	625,000
Number of Shares, Shares available for future option grants at September 30, 2014	285,376
Aggregate Intrinsic Value, Outstanding, Beginning Balance	$ 1,516
Aggregate Intrinsic Value, Exercised	339
Aggregate Intrinsic Value, Outstanding, Ending Balance	1,651	1,516
Aggregate Intrinsic Value, Options exercisable at September 30, 2014	1,076
Aggregate Intrinsic Value, Unvested options expected to become exercisable after September 30, 2014	$ 633
Approximate Remaining Contractual Term, Outstanding	9 years	8 years
Approximate Remaining Contractual Term, Granted	10 years
Approximate Remaining Contractual Term, Options exercisable at September 30, 2014	8 years
Approximate Remaining Contractual Term, Unvested options expected to become exercisable after September 30, 2014	9 years
Weighted-Average Exercise Price Outstanding, Beginning Balance	$ 8.15
Weighted-Average Exercise Price, Granted	$ 11.59
Weighted-Average Exercise Price, Exercised	$ 7.46
Weighted-Average Exercise Price, Canceled or expired	$ 8.59
Weighted-Average Exercise Price, Outstanding, Ending Balance	$ 9.18	$ 8.15
Weighted-Average Exercise Price, Options exercisable at September 30, 2014	$ 8.64
Weighted-Average Exercise Price, Unvested options expected to become exercisable after September 30, 2014	$ 9.79