Income Taxes - Provision for Income Taxes from Continuing Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Federal	$ (230)	$ 312	$ 50
State and local, including Puerto Rico	(20)	17	15
Foreign	200	286	252
Total, Current	(50)	616	318
Domestic	(64)	(441)	(238)
Foreign	(10)	(78)	(37)
Total, Deferred	(74)	(519)	(274)
Income tax provision	$ (124)	$ 97	$ 44