Summary of Stock Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Dec. 31, 2013	Mar. 31, 2013
Options
Beginning Balance	4,228
Granted	333
Exercised	(907)
Cancelled and expired	(37)
Ending Balance	3,617	4,228
Exercisable at December 31, 2013	2,798
Options vested and expected to vest at December 31, 2013	3,521
Weighted-Average Exercise Price
Beginning Balance	$ 11.49
Granted	$ 23.53
Exercised	$ 9.18
Cancelled and expired	$ 18.74
Ending Balance	$ 13.10	$ 11.49
Exercisable at December 31, 2013	$ 11.25
Options vested and expected to vest at December 31, 2013	$ 13.00
Weighted-Average Remaining Contractual Term (years)
Outstanding	5 years 1 month 17 days	5 years 4 months 13 days
Exercisable at December 31, 2013	4 years 2 months 5 days
Options vested and expected to vest at December 31, 2013	5 years 22 days
Aggregate Intrinsic Value
Outstanding at December 31, 2013	$ 49,330
Exercisable at December 31, 2013	43,350
Options vested and expected to vest at December 31, 2013	$ 48,397