Reportable Operating Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Total non-interest revenues	$ 13,669	$ 12,603	$ 26,467	$ 24,635
Revenue from contracts with customers	10,321	9,818	19,947	19,157
Interest income	6,264	5,794	12,399	11,569
Interest expense	2,077	2,064	4,043	4,070
Net interest income	4,187	3,730	8,356	7,499
Total revenues net of interest expense	17,856	16,333	34,823	32,134
Provisions for credit losses	1,405	1,268	2,555	2,537
Total revenues net of interest expense after provisions for credit losses	16,451	15,065	32,268	29,597
Card Member rewards, business development and Card Member services	7,508	6,808	14,743	13,145
Marketing	1,555	1,480	3,041	2,956
Salaries and employee benefits and other operating expenses	3,838	2,987	7,604	6,561
Total expenses	12,901	11,275	25,388	22,662
Pretax income	3,550	3,790	6,880	6,935
Total assets	295,556	272,219	295,556	272,219	$ 271,461
Corporate and Other
Segment Reporting Information [Line Items]
Total non-interest revenues	2	9	(14)	(11)
Revenue from contracts with customers	(7)	14	(16)	4
Interest income	599	679	1,161	1,368
Interest expense	675	736	1,289	1,471
Net interest income	(76)	(57)	(128)	(103)
Total revenues net of interest expense	(74)	(48)	(142)	(114)
Provisions for credit losses	1	1	1	0
Total revenues net of interest expense after provisions for credit losses	(75)	(49)	(143)	(114)
Card Member rewards, business development and Card Member services	11	8	23	14
Marketing	6	5	14	11
Salaries and employee benefits and other operating expenses	458	440	979	978
Total expenses	475	453	1,016	1,003
Pretax income	(550)	(502)	(1,159)	(1,117)
Total assets	54,704	38,574	54,704	38,574
USCS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	5,540	5,029	10,783	9,795
Revenue from contracts with customers	3,903	3,696	7,537	7,165
Interest income	3,795	3,474	7,558	6,955
Interest expense	782	771	1,539	1,519
Net interest income	3,013	2,703	6,019	5,436
Total revenues net of interest expense	8,553	7,732	16,802	15,231
Provisions for credit losses	829	706	1,460	1,433
Total revenues net of interest expense after provisions for credit losses	7,724	7,026	15,342	13,798
Card Member rewards, business development and Card Member services	3,967	3,587	7,849	6,943
Marketing	800	764	1,565	1,483
Salaries and employee benefits and other operating expenses	1,281	1,115	2,520	2,199
Total expenses	6,048	5,466	11,934	10,625
Pretax income	1,676	1,560	3,408	3,173
Total assets	113,876	108,224	113,876	108,224
CS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	3,422	3,333	6,687	6,527
Revenue from contracts with customers	2,975	2,922	5,803	5,717
Interest income	1,240	1,051	2,442	2,056
Interest expense	450	430	882	844
Net interest income	790	621	1,560	1,212
Total revenues net of interest expense	4,212	3,954	8,247	7,739
Provisions for credit losses	360	349	689	704
Total revenues net of interest expense after provisions for credit losses	3,852	3,605	7,558	7,035
Card Member rewards, business development and Card Member services	1,790	1,633	3,536	3,126
Marketing	331	325	668	651
Salaries and employee benefits and other operating expenses	826	742	1,613	1,475
Total expenses	2,947	2,700	5,817	5,252
Pretax income	905	905	1,741	1,783
Total assets	62,152	58,993	62,152	58,993
ICS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	2,947	2,548	5,593	4,985
Revenue from contracts with customers	1,876	1,669	3,564	3,259
Interest income	620	577	1,216	1,160
Interest expense	335	303	641	610
Net interest income	285	274	575	550
Total revenues net of interest expense	3,232	2,822	6,168	5,535
Provisions for credit losses	210	192	402	374
Total revenues net of interest expense after provisions for credit losses	3,022	2,630	5,766	5,161
Card Member rewards, business development and Card Member services	1,452	1,302	2,764	2,505
Marketing	322	290	622	642
Salaries and employee benefits and other operating expenses	783	748	1,534	1,472
Total expenses	2,557	2,340	4,920	4,619
Pretax income	465	290	846	542
Total assets	46,500	41,982	46,500	41,982
GMNS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	1,758	1,684	3,418	3,339
Revenue from contracts with customers	1,574	1,517	3,059	3,012
Interest income	10	13	22	30
Interest expense	(165)	(176)	(308)	(374)
Net interest income	175	189	330	404
Total revenues net of interest expense	1,933	1,873	3,748	3,743
Provisions for credit losses	5	20	3	26
Total revenues net of interest expense after provisions for credit losses	1,928	1,853	3,745	3,717
Card Member rewards, business development and Card Member services	288	278	571	557
Marketing	96	96	172	169
Salaries and employee benefits and other operating expenses	490	(58)	958	437
Total expenses	874	316	1,701	1,163
Pretax income	1,054	1,537	2,044	2,554
Total assets	$ 18,324	$ 24,446	$ 18,324	$ 24,446