Income Taxes - Deferred Income Taxes (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
Compensation and benefits, assets	$ 647	$ 546
Loss and credit carryforwards, assets	538	274
Other, assets	634	398
Deferred income taxes, assets, gross	1,819	1,218
Valuation allowance, assets	(452)	(247)
Deferred income taxes, assets	1,367	971
Property and equipment, liabilities	156	196
Deferred Tax Liabilities, Other Finite-Lived Assets	2,033	266
Other, liabilities	606	195
Deferred income taxes, liabilities, gross	2,795	656
Deferred income taxes, liabilities	$ 2,795	$ 656