Summary of RSA and RSU Activity (Detail) - $ / shares		12 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Aggregate Intrinsic Value
Stock price used to calculate aggregate intrinsic value		$ 105.24
Restricted Stock Awards
Restricted stock
Beginning balance		1,766,582
Granted		0	0
Vested		(1,210,176)
Forfeited		(90,399)
Ending balance		466,007	1,766,582
Weighted-Average Grant Date Fair Value
Beginning balance		$ 59.26
Granted		0.00		$ 63.71
Vested		57.37
Forfeited		61.90
Ending balance		$ 63.37	$ 59.26
Weighted-Average Remaining Contactual Term
Outstanding at September 30, 2017		2 months 21 days
Aggregate Intrinsic Value
Outstanding at September 30, 2017	[1]	$ 49,000,000
Restricted Stock Units
Restricted stock
Beginning balance		3,146,954
Granted		3,268,327
Vested		(1,299,187)
Forfeited		(442,393)
Ending balance		4,673,701	3,146,954
Weighted-Average Grant Date Fair Value
Beginning balance		$ 75.48
Granted		81.67	$ 79.77	$ 62.88
Vested		72.20
Forfeited		79.34
Ending balance		$ 80.37	$ 75.48
Weighted-Average Remaining Contactual Term
Outstanding at September 30, 2017		1 year 7 months 6 days
Aggregate Intrinsic Value
Outstanding at September 30, 2017	[1]	$ 492,000,000

[1] Calculated by multiplying the closing stock price on the last trading day of fiscal 2017 of $105.24 by the number of instruments.