Reportable Operating Segments and Geographic Operations - Selected Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Total non-interest revenues	$ 50,406	$ 47,381	$ 42,967
Revenue from contracts with customers	38,825	37,218	34,219
Interest income	23,795	19,983	12,658
Interest expense	8,252	6,849	2,763
Net interest income	15,543	13,134	9,895
Total revenues net of interest expense	65,949	60,515	52,862
Provisions	5,185	4,923	2,182
Total revenues net of interest expense after provisions for credit losses	60,764	55,592	50,680
Card Member rewards, business development and Card Member services	27,267	24,992	21,904
Marketing	6,040	5,213	5,458
Salaries and employee benefits and other operating expenses	14,562	14,874	13,733
Total expenses	47,869	45,079	41,095
Pretax income (loss)	12,895	10,513	9,585
Total assets	271,461	261,108	228,354
Corporate and Other
Segment Reporting Information [Line Items]
Total non-interest revenues	(48)	(106)	(54)
Revenue from contracts with customers	(32)	(37)	(7)
Interest income	2,608	2,186	655
Interest expense	2,842	2,283	758
Net interest income	(234)	(97)	(103)
Total revenues net of interest expense	(282)	(203)	(157)
Provisions	(1)	1	5
Total revenues net of interest expense after provisions for credit losses	(281)	(204)	(162)
Card Member rewards, business development and Card Member services	43	46	(11)
Marketing	24	20	27
Salaries and employee benefits and other operating expenses	2,068	2,140	2,049
Total expenses	2,135	2,206	2,065
Pretax income (loss)	(2,416)	(2,410)	(2,227)
Total assets	37,673	32,641	25,603
USCS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	20,137	18,464	16,440
Revenue from contracts with customers	14,481	13,715	12,478
Interest income	14,430	12,336	8,457
Interest expense	3,140	2,684	983
Net interest income	11,290	9,652	7,474
Total revenues net of interest expense	31,427	28,116	23,914
Provisions	3,029	2,855	1,021
Total revenues net of interest expense after provisions for credit losses	28,398	25,261	22,893
Card Member rewards, business development and Card Member services	14,329	12,808	10,791
Marketing	3,051	2,585	2,744
Salaries and employee benefits and other operating expenses	4,641	4,435	3,958
Total expenses	22,021	19,828	17,493
Pretax income (loss)	6,377	5,433	5,400
Total assets	114,228	107,158	94,444
CS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	13,219	12,931	12,196
Revenue from contracts with customers	11,559	11,379	10,844
Interest income	4,374	3,328	2,070
Interest expense	1,734	1,483	697
Net interest income	2,640	1,845	1,373
Total revenues net of interest expense	15,859	14,776	13,569
Provisions	1,389	1,313	565
Total revenues net of interest expense after provisions for credit losses	14,470	13,463	13,004
Card Member rewards, business development and Card Member services	6,504	6,332	6,116
Marketing	1,319	1,090	1,122
Salaries and employee benefits and other operating expenses	3,142	3,180	2,886
Total expenses	10,965	10,602	10,124
Pretax income (loss)	3,505	2,861	2,880
Total assets	58,969	55,361	51,411
ICS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	10,369	9,472	8,262
Revenue from contracts with customers	6,766	6,155	5,301
Interest income	2,331	2,076	1,453
Interest expense	1,239	1,118	654
Net interest income	1,092	958	799
Total revenues net of interest expense	11,461	10,430	9,061
Provisions	726	727	584
Total revenues net of interest expense after provisions for credit losses	10,735	9,703	8,477
Card Member rewards, business development and Card Member services	5,243	4,588	3,816
Marketing	1,235	1,081	1,146
Salaries and employee benefits and other operating expenses	3,226	3,061	2,937
Total expenses	9,704	8,730	7,899
Pretax income (loss)	1,031	973	578
Total assets	42,879	42,234	36,891
GMNS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	6,729	6,620	6,123
Revenue from contracts with customers	6,051	6,006	5,603
Interest income	52	57	23
Interest expense	(703)	(719)	(329)
Net interest income	755	776	352
Total revenues net of interest expense	7,484	7,396	6,475
Provisions	42	27	7
Total revenues net of interest expense after provisions for credit losses	7,442	7,369	6,468
Card Member rewards, business development and Card Member services	1,148	1,218	1,192
Marketing	411	437	419
Salaries and employee benefits and other operating expenses	1,485	2,058	1,903
Total expenses	3,044	3,713	3,514
Pretax income (loss)	4,398	3,656	2,954
Total assets	$ 17,712	$ 23,714	$ 20,005