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, 2017 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding, Beginning Balance | shares	1,833,437
Number of Shares, Options granted | shares	463,000
Number of Shares, Options canceled | shares	(19,125)
Number of Shares, Options exercised | shares	(273,050)
Number of Shares, Outstanding, Ending Balance | shares	2,004,262
Number of Shares, Vested and exercisable, Ending Balance | shares	1,011,200
Weighted Average Exercise Price per Share, Outstanding, Beginning Balance | $ / shares	$ 54.07
Weighted Average Exercise Price per Share, Options granted | $ / shares	70.09
Weighted Average Exercise Price per Share, Options canceled | $ / shares	64.66
Weighted Average Exercise Price per Share, Options exercised | $ / shares	44.37
Weighted Average Exercise Price per Share, Outstanding, Ending Balance | $ / shares	58.99
Weighted Average Exercise Price per Share, Vested and exercisable, Ending Balance | $ / shares	$ 52.19
Weighted Average Remaining Contractual Term in Years, Outstanding	3 years 6 months 11 days
Weighted Average Remaining Contractual Term in Years, Vested and exercisable	2 years 3 months 22 days
Aggregate Intrinsic Value, Outstanding | $	$ 13,283
Aggregate Intrinsic Value, Vested and exercisable | $	$ 12,147