Summary of Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Dec. 31, 2013
Shares
Beginning Balance	2,687
Granted	14
Exercised	(354)
Forfeited	(59)
Expired	(5)
Ending Balance	2,283
Options exercisable at December 31, 2013	965
Vested and expected to vest at December 31, 2013	2,098
Weighted-average Exercise Price
Beginning Balance	$ 35.48
Granted	$ 57.59
Exercised	$ 33.16
Forfeited	$ 41.46
Expired	$ 35.50
Ending Balance	$ 35.83
Options exercisable at December 31, 2013	$ 32.00
Vested and expected to vest at December 31, 2013	$ 35.42
Weighted-average Remaining Contractual Term
Outstanding at December 31, 2013	4 years 9 months 22 days
Options exercisable at December 31, 2013	3 years 11 months 19 days
Vested and expected to vest at December 31, 2013	4 years 8 months 27 days
Aggregate Intrinsic Value
Outstanding at December 31, 2013	$ 61,675
Options exercisable at December 31, 2013	29,761
Vested and expected to vest at December 31, 2013	$ 57,529