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, 2013	Mar. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding, Beginning Balance	1,231,498
Number of Shares, Granted	158,000	551,000
Number of Shares, Exercised	(88,500)
Number of Shares, Canceled or expired	(325,785)
Number of Shares, Outstanding, Ending Balance	975,213	1,231,498
Number of Shares, Options exercisable at September 30, 2013	414,880
Number of Shares, Unvested options expected to become exercisable after September 30, 2013	560,333
Number of Shares, Shares available for future option grants at September 30, 2013	501,113
Aggregate Intrinsic Value, Outstanding, Beginning Balance	$ 720
Aggregate Intrinsic Value, Granted
Aggregate Intrinsic Value, Exercised	159
Aggregate Intrinsic Value, Canceled or expired
Aggregate Intrinsic Value, Outstanding, Ending Balance	1,547	720
Average Intrinsic Value, Options exercisable at September 30, 2013	716
Aggregate Intrinsic Value, Unvested options expected to become exercisable after September 30, 2013	$ 831
Approximate Remaining Contractual Term, Outstanding	8 years	7 years
Approximate Remaining Contractual Term, Granted	10 years
Approximate Remaining Contractual Term, Options exercisable at September 30, 2013	6 years
Approximate Remaining Contractual Term, Unvested options expected to become exercisable after September 30, 2013	9 years
Weighted-Average Exercise Price Outstanding, Beginning Balance	$ 8.20
Weighted-Average Exercise Price, Granted	$ 8.58
Weighted-Average Exercise Price, Exercised	$ 6.86
Weighted-Average Exercise Price, Canceled or expired	$ 9.32
Weighted-Average Exercise Price, Outstanding, Ending Balance	$ 8.34	$ 8.20
Weighted-Average Exercise Price, Options exercisable at September 30, 2013	$ 8.43
Weighted-Average Exercise Price, Unvested options expected to become exercisable after September 30, 2013	$ 8.28