Common Stock and Stock Plans - Summary of Employee Stock Option Activity (Detail) - Employee Stock Options [Member] $ / shares in Units, $ in Thousands	12 Months Ended
	Mar. 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding, Beginning Balance | shares	1,827,143
Number of Shares, Options granted | shares	439,000
Number of Shares, Options canceled | shares	0
Number of Shares, Options exercised | shares	(432,706)
Number of Shares, Outstanding, Ending Balance | shares	1,833,437
Number of Shares, Vested and exercisable, Ending Balance | shares	921,513
Weighted Average Exercise Price per Share, Outstanding, Beginning Balance | $ / shares	$ 46.90
Weighted Average Exercise Price per Share, Options granted | $ / shares	61.42
Weighted Average Exercise Price per Share, Options canceled | $ / shares	0
Weighted Average Exercise Price per Share, Options exercised | $ / shares	31.25
Weighted Average Exercise Price per Share, Outstanding, Ending Balance | $ / shares	54.07
Weighted Average Exercise Price per Share, Vested and exercisable, Ending Balance | $ / shares	$ 47.84
Weighted Average Remaining Contractual Term in Years, Outstanding	3 years 6 months 26 days
Weighted Average Remaining Contractual Term in Years, Vested and exercisable	2 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding | $	$ 35,593
Aggregate Intrinsic Value, Vested and exercisable | $	$ 23,632