Stock Option Activity (Detail) (USD $)	6 Months Ended
	Sep. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding Options at Beginning of Period	2,788,999
Number of Shares, Granted	217,151
Number of Shares, Exercised	(144,420)
Number of Shares, Cancelled	(1,269,500)
Number of Shares, Outstanding Options at End of Period	1,592,230
Number of Shares, Options Exercisable at End of Period	1,037,331
Weighted-Average Exercise Price, Weighted-Average Fair Value of Options Granted during the Period	$ 32.44
Weighted-Average Exercise Price, Outstanding Options at Beginning of Period	$ 41.83
Weighted-Average Exercise Price, Granted	$ 87.91
Weighted-Average Exercise Price, Exercised	$ 32.36
Weighted-Average Exercise Price, Cancelled	$ 47.50
Weighted-Average Exercise Price, Outstanding Options at End of Period	$ 44.49
Weighted-Average Exercise Price, Options Exercisable at End of Period	$ 34.33