Line of Business Information - Components of Other (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net repositioning charges	$ 133	$ 110	$ 300
Acquisition and restructuring costs	50	77	24
Total	(2,899)	(2,712)	(3,101)
Other
Segment Reporting Information [Line Items]
Net repositioning charges	133	110	300
Acquisition and restructuring costs	50	77	24
Accrual release	(9)	0	0
Legal and related expenses	0	172	50
Business exit costs	0	0	24
Total	174	359	398
Total expenses	$ 174	$ 359	$ 398