Supplementary Data (Unaudited) - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 4,584	$ 4,350	$ 4,195	$ 4,160	$ 4,402	$ 4,278	$ 4,222	$ 3,080	$ 17,290	$ 15,983	$ 12,093
Gross Profit	2,266	2,074	1,974	1,974	2,094	2,017	1,606	1,553	8,288	7,269
Net Income	$ 163	$ 451	$ 20	$ 599	$ (135)	$ 594	$ (12)	$ (136)	$ 1,233	$ 311	$ 1,100
(Loss) earnings per Share: (a)
Basic Earnings per Share (USD per share)	$ 0.46	$ 1.53	$ (0.07)	$ 2.09	$ (0.64)	$ 2.08	$ (0.19)	$ (0.76)	$ 4.01	$ 0.62	$ 4.70
Diluted Earnings per Share (USD per share)	$ 0.45	$ 1.51	$ (0.07)	$ 2.05	$ (0.64)	$ 2.03	$ (0.19)	$ (0.76)	$ 3.94	$ 0.60	$ 4.60