Supplemental Financial Information - Other Income (Expense), Net (Detail) - USD ($) $ in Millions	1 Months Ended		3 Months Ended		12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Losses on debt extinguishment	$ 31	$ 42	$ 3	$ 13	$ (16)	$ (73)	$ 0
Income (Loss) from Equity Method Investments					8	3	8
Losses on undesignated foreign exchange derivatives, net					(14)	(11)	(3)
Royalty Income, Nonoperating					51	0	0
Gains on previously held investments					0	24	0
Other					0	3	7
Other income (expense), net					318	(57)	11
Vyaire Medical [Member]
Income (Loss) from Equity Method Investments					$ 288	$ (3)	$ 0