Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate reconciliation, percent	22.00%	33.00%		28.00%	29.00%
Unrecognized tax benefits, decrease resulting from settlements with taxing authorities	$ 280
Unrecognized tax benefits, decrease resulting from prior period tax positions	239
Unrecognized tax benefits, decrease resulting from tax positions taken in Q1 and Q2 of fiscal 2015	24
Tax benefit related to deduction for U.S. domestic production activities			$ 189
Decrease in unrecognized tax benefits	245			$ 254
Unrecognized tax benefits, decrease in accrued interest	$ 8			$ 4