Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares
Options Outstanding, Shares
Beginning Balance | shares	939
Granted | shares	25
Exercised | shares	(5)
Forfeited/Expired | shares	(10)
Ending Balance | shares	949
Exercisable as of June 30, 2017 | shares	514
Expected to vest as of June 30, 2017 | shares	435
Total | shares	949
Weighted Average Exercise Price Per Share
Beginning Balance | $ / shares	$ 146.27
Granted | $ / shares	182.64
Exercised | $ / shares	119.02
Forfeited/Expired | $ / shares	201.25
Ending Balance | $ / shares	146.79
Exercisable as of June 30, 2017 | $ / shares	133.39
Expected to vest as of June 30, 2017 | $ / shares	162.64
Total | $ / shares	$ 146.79
Aggregate Intrinsic Value
Exercised | $	$ 329
Exercisable as of June 30, 2017 | $	30,133
Expected to vest as of June 30, 2017 | $	13,130
Total | $	$ 43,263
Weighted Average Remaining Contractual Term (Years)
Exercisable as of June 30, 2017	7 years 1 month 6 days
Expected to vest as of June 30, 2017	8 years 1 month 6 days
Total	7 years 6 months