Reportable Operating Segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Total non-interest revenues	$ 12,798	$ 12,032
Revenue from contracts with customers	9,626	9,339
Interest income	6,135	5,775
Interest expense	1,966	2,006
Net interest income	4,169	3,769
Total revenues net of interest expense	16,967	15,801
Provisions for credit losses	1,150	1,269
Total revenues net of interest expense after provisions for credit losses	15,817	14,532
Card Member rewards, business development and Card Member services	7,235	6,337
Marketing	1,486	1,476
Salaries and employee benefits and other operating expenses	3,766	3,574
Total expenses	12,487	11,387
Pretax income	3,330	3,145
Total assets	282,244	269,261	$ 271,461
Corporate and Other
Segment Reporting Information [Line Items]
Total non-interest revenues	(16)	(20)
Revenue from contracts with customers	(9)	(10)
Interest income	562	689
Interest expense	614	735
Net interest income	(52)	(46)
Total revenues net of interest expense	(68)	(66)
Provisions for credit losses	0	(1)
Total revenues net of interest expense after provisions for credit losses	(68)	(65)
Card Member rewards, business development and Card Member services	12	6
Marketing	8	6
Salaries and employee benefits and other operating expenses	521	538
Total expenses	541	550
Pretax income	(609)	(615)
Total assets	48,643	40,464
USCS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	5,243	4,766
Revenue from contracts with customers	3,634	3,469
Interest income	3,763	3,481
Interest expense	757	748
Net interest income	3,006	2,733
Total revenues net of interest expense	8,249	7,499
Provisions for credit losses	631	727
Total revenues net of interest expense after provisions for credit losses	7,618	6,772
Card Member rewards, business development and Card Member services	3,882	3,356
Marketing	765	719
Salaries and employee benefits and other operating expenses	1,239	1,084
Total expenses	5,886	5,159
Pretax income	1,732	1,613
Total assets	110,886	104,297
CS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	3,265	3,194
Revenue from contracts with customers	2,828	2,795
Interest income	1,202	1,005
Interest expense	432	414
Net interest income	770	591
Total revenues net of interest expense	4,035	3,785
Provisions for credit losses	329	355
Total revenues net of interest expense after provisions for credit losses	3,706	3,430
Card Member rewards, business development and Card Member services	1,746	1,493
Marketing	337	326
Salaries and employee benefits and other operating expenses	787	733
Total expenses	2,870	2,552
Pretax income	836	878
Total assets	62,012	58,143
ICS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	2,646	2,437
Revenue from contracts with customers	1,688	1,590
Interest income	596	583
Interest expense	306	307
Net interest income	290	276
Total revenues net of interest expense	2,936	2,713
Provisions for credit losses	192	182
Total revenues net of interest expense after provisions for credit losses	2,744	2,531
Card Member rewards, business development and Card Member services	1,312	1,203
Marketing	300	352
Salaries and employee benefits and other operating expenses	751	724
Total expenses	2,363	2,279
Pretax income	381	252
Total assets	42,620	41,472
GMNS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	1,660	1,655
Revenue from contracts with customers	1,485	1,495
Interest income	12	17
Interest expense	(143)	(198)
Net interest income	155	215
Total revenues net of interest expense	1,815	1,870
Provisions for credit losses	(2)	6
Total revenues net of interest expense after provisions for credit losses	1,817	1,864
Card Member rewards, business development and Card Member services	283	279
Marketing	76	73
Salaries and employee benefits and other operating expenses	468	495
Total expenses	827	847
Pretax income	990	1,017
Total assets	$ 18,083	$ 24,885