Reportable Operating Segments and Geographic Operations (Details 1) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense	$ 9,351	$ 8,751	$ 7,675	$ 10,310	$ 11,365	$ 10,989	$ 10,838	$ 10,364	$ 36,087	$ 43,556	$ 40,338
Pretax income	$ 1,858	$ 1,364	$ 622	$ 452	$ 1,986	$ 2,266	$ 2,219	$ 1,958	4,296	8,429	8,122
United States [Member]
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense									28,263	32,629	29,886
Pretax income									4,418	7,302	6,686
EMEA [Member]
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense									3,087	4,388	4,348
Pretax income									398	1,177	1,163
APAC Geographic Region [Member]
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense									3,271	3,934	3,690
Pretax income									665	853	792
LACC Geographic Region [Member]
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense									2,019	2,776	2,576
Pretax income									452	884	787
Other Unallocated [Member]
Segment Revenues And Pretax Income Loss By Geographic Location [Line Items]
Total revenues net of interest expense									(553)	(171)	(162)
Pretax income									$ (1,638)	$ (1,787)	$ (1,306)