Summary of Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2014
Shares
Outstanding at October 1, 2013	2,687
Granted	58
Exercised	(583)
Forfeited	(68)
Expired	(5)
Outstanding at September 30, 2014	2,089
Options exercisable at September 30, 2014	998
Vested and expected to vest at September 30, 2014	1,990
Weighted- average Exercise Price
Outstanding at October 1, 2013 (in dollars per share)	$ 35.48
Granted (in dollars per share)	$ 53.82
Exercised (in dollars per share)	$ 33.91
Forfeited (in dollars per share)	$ 41.30
Expired (in dollars per share)	$ 35.37
Outstanding at September 30, 2014 (in dollars per share)	$ 36.24
Options exercisable at September 30, 2014 (in dollars per share)	$ 33.28
Vested and expected to vest at September 30, 2014 (in dollars per share)	$ 35.97
Weighted- average Remaining Contractual Term
Outstanding at September 30, 2014	4 years 3 months 22 days
Options exercisable at September 30, 2014	3 years 10 months 5 days
Vested and expected to vest at September 30, 2014	4 years 3 months 10 days
Aggregate Intrinsic Value
Outstanding at September 30, 2014	$ 39,436
Options exercisable at September 30, 2014	21,787
Vested and expected to vest at September 30, 2014	$ 38,090