Reportable Operating Segments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Total non-interest revenues	$ 13,940	$ 12,630	$ 40,407	$ 37,265
Revenue from contracts with customers	10,415	9,716	30,362	28,873
Interest income	6,617	6,149	19,016	17,718
Interest expense	2,131	2,143	6,174	6,213
Net interest income	4,486	4,006	12,842	11,505
Total revenues net of interest expense	18,426	16,636	53,249	48,770
Provisions for credit losses	1,287	1,356	3,842	3,893
Total revenues net of interest expense after provisions for credit losses	17,139	15,280	49,407	44,877
Card Member rewards, business development and Card Member services	7,696	6,777	22,439	19,922
Marketing	1,599	1,470	4,640	4,426
Salaries and employee benefits and other operating expenses	4,019	3,829	11,623	10,390
Total expenses	13,314	12,076	38,702	34,738
Pretax income	3,825	3,204	10,705	10,139
Total assets	297,550	270,979	297,550	270,979	$ 271,461
Corporate and Other
Segment Reporting Information [Line Items]
Total non-interest revenues	63	(28)	49	(39)
Revenue from contracts with customers	(10)	(7)	(26)	(3)
Interest income	629	686	1,790	2,054
Interest expense	711	747	2,000	2,218
Net interest income	(82)	(61)	(210)	(164)
Total revenues net of interest expense	(19)	(89)	(161)	(203)
Provisions for credit losses	(2)	2	(1)	2
Total revenues net of interest expense after provisions for credit losses	(17)	(91)	(160)	(205)
Card Member rewards, business development and Card Member services	11	15	34	29
Marketing	6	8	20	19
Salaries and employee benefits and other operating expenses	564	695	1,543	1,673
Total expenses	581	718	1,597	1,721
Pretax income	(598)	(809)	(1,757)	(1,926)
Total assets	51,783	44,250	51,783	44,250
USCS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	5,620	5,028	16,403	14,823
Revenue from contracts with customers	3,925	3,620	11,462	10,785
Interest income	4,025	3,722	11,583	10,677
Interest expense	789	806	2,328	2,325
Net interest income	3,236	2,916	9,255	8,352
Total revenues net of interest expense	8,856	7,944	25,658	23,175
Provisions for credit losses	734	812	2,194	2,245
Total revenues net of interest expense after provisions for credit losses	8,122	7,132	23,464	20,930
Card Member rewards, business development and Card Member services	4,145	3,570	11,994	10,513
Marketing	825	755	2,390	2,238
Salaries and employee benefits and other operating expenses	1,300	1,148	3,820	3,347
Total expenses	6,270	5,473	18,204	16,098
Pretax income	1,852	1,659	5,260	4,832
Total assets	115,330	106,201	115,330	106,201
CS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	3,441	3,304	10,128	9,831
Revenue from contracts with customers	2,986	2,886	8,789	8,603
Interest income	1,302	1,142	3,744	3,198
Interest expense	462	448	1,344	1,292
Net interest income	840	694	2,400	1,906
Total revenues net of interest expense	4,281	3,998	12,528	11,737
Provisions for credit losses	332	374	1,021	1,078
Total revenues net of interest expense after provisions for credit losses	3,949	3,624	11,507	10,659
Card Member rewards, business development and Card Member services	1,730	1,627	5,266	4,753
Marketing	313	308	981	959
Salaries and employee benefits and other operating expenses	816	781	2,429	2,256
Total expenses	2,859	2,716	8,676	7,968
Pretax income	1,090	908	2,831	2,691
Total assets	64,305	59,716	64,305	59,716
ICS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	3,034	2,659	8,627	7,644
Revenue from contracts with customers	1,928	1,724	5,492	4,983
Interest income	652	588	1,868	1,748
Interest expense	350	311	991	921
Net interest income	302	277	877	827
Total revenues net of interest expense	3,336	2,936	9,504	8,471
Provisions for credit losses	218	158	620	532
Total revenues net of interest expense after provisions for credit losses	3,118	2,778	8,884	7,939
Card Member rewards, business development and Card Member services	1,512	1,296	4,276	3,801
Marketing	350	287	972	929
Salaries and employee benefits and other operating expenses	815	740	2,349	2,212
Total expenses	2,677	2,323	7,597	6,942
Pretax income	441	455	1,287	997
Total assets	47,253	43,073	47,253	43,073
GMNS | Operating Segments
Segment Reporting Information [Line Items]
Total non-interest revenues	1,782	1,667	5,200	5,006
Revenue from contracts with customers	1,586	1,493	4,645	4,505
Interest income	9	11	31	41
Interest expense	(181)	(169)	(489)	(543)
Net interest income	190	180	520	584
Total revenues net of interest expense	1,972	1,847	5,720	5,590
Provisions for credit losses	5	10	8	36
Total revenues net of interest expense after provisions for credit losses	1,967	1,837	5,712	5,554
Card Member rewards, business development and Card Member services	298	269	869	826
Marketing	105	112	277	281
Salaries and employee benefits and other operating expenses	524	465	1,482	902
Total expenses	927	846	2,628	2,009
Pretax income	1,040	991	3,084	3,545
Total assets	$ 18,879	$ 17,739	$ 18,879	$ 17,739