Expenses - Restructuring Reserve (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023
Restructuring Reserve [Roll Forward]
Beginning balance	$ 189	$ 208	$ 73	$ 88
Payments and other adjustments	(37)	(19)	(17)	(15)
Ending balance	152	189	56	73
Employee Related Costs
Restructuring Reserve [Roll Forward]
Beginning balance	188	207	69	83
Payments and other adjustments	(37)	(19)	(16)	(14)
Ending balance	151	188	53	69
Real Estate Actions
Restructuring Reserve [Roll Forward]
Beginning balance	1	1	4	5
Payments and other adjustments	0	0	(1)	(1)
Ending balance	$ 1	$ 1	$ 3	$ 4