Significant Restructuring and Impairment Costs - Schedule of Restructuring Reserve by Type of Cost (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Restructuring Reserve [Roll Forward]
Additional restructuring costs	$ 418		$ 384	$ 763	$ 433
Various 2023 Restructuring Plans
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	43	$ 57		57
Additional restructuring costs	24			81
Utilized—cash	(40)	(8)
Utilized—noncash	(4)	(6)
Restructuring reserve, ending balance	23	43		23
Employee Severance and Termination Benefits | Various 2023 Restructuring Plans
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	27	30		30
Additional restructuring costs	17
Utilized—cash	(32)	(3)
Utilized—noncash	0	0
Restructuring reserve, ending balance	12	27		12
Long-Lived Asset Impairments | Various 2023 Restructuring Plans
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	0	6		6
Additional restructuring costs	4
Utilized—cash	0	0
Utilized—noncash	(4)	(6)
Restructuring reserve, ending balance	0	0		0
Other | Various 2023 Restructuring Plans
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	16	21		21
Additional restructuring costs	3
Utilized—cash	(8)	(5)
Utilized—noncash	0	0
Restructuring reserve, ending balance	$ 11	$ 16		$ 11