Reportable Operating Segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Total non-interest revenues	$ 12,032	$ 11,298
Revenue from contracts with customers	9,339	8,846
Interest income	5,775	4,416
Interest expense	2,006	1,433
Total revenues net of interest expense	15,801	14,281
Pretax income (loss)	3,145	2,167
Total assets	269,261	236,000	$ 261,108
Corporate and Other
Segment Reporting Information [Line Items]
Total non-interest revenues	(20)	(31)
Revenue from contracts with customers	(10)	(13)
Interest income	689	454
Interest expense	735	468
Total revenues net of interest expense	(66)	(45)
Pretax income (loss)	(615)	(667)
Total assets	41,000	38,000
USCS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	4,766	4,359
Revenue from contracts with customers	3,469	3,239
Interest income	3,481	2,775
Interest expense	748	551
Total revenues net of interest expense	7,499	6,583
Pretax income (loss)	1,613	1,130
Total assets	104,000	91,000
CS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	3,194	3,107
Revenue from contracts with customers	2,795	2,731
Interest income	1,005	706
Interest expense	414	321
Total revenues net of interest expense	3,785	3,492
Pretax income (loss)	878	630
Total assets	58,000	54,000
ICS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	2,437	2,267
Revenue from contracts with customers	1,590	1,441
Interest income	583	467
Interest expense	307	224
Total revenues net of interest expense	2,713	2,510
Pretax income (loss)	252	189
Total assets	41,000	36,000
GMNS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	1,655	1,596
Revenue from contracts with customers	1,495	1,448
Interest income	17	14
Interest expense	(198)	(131)
Total revenues net of interest expense	1,870	1,741
Pretax income (loss)	1,017	885
Total assets	$ 25,000	$ 17,000