Business Segments and Revenue from Contracts with Customers - Segment Results and Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net interest income (loss)	$ 7,546	$ 7,113	$ 15,034	$ 14,299
Non-interest income	1,960	1,899	3,874	3,616
Total net revenue (loss)	9,506	9,012	18,908	17,915
Provision for credit losses	3,909	2,490	6,592	5,285
Non-interest expense	4,946	4,794	10,083	9,739
Income (Loss) from continuing operations before income taxes	651	1,728	2,233	2,891
Income tax provision (benefit)	54	297	356	500
Income (loss) from continuing operations, net of tax	597	1,431	1,877	2,391
Loans held for investment	318,186	311,323	318,186	311,323
Deposits	351,442	343,705	351,442	343,705	$ 348,413
Uncollectible portion of billed finance charges and fees	649	443	1,300	848
Operating segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income (loss)	5,294	4,727	10,566	9,384
Non-interest income	1,506	1,499	2,982	2,862
Total net revenue (loss)	6,800	6,226	13,548	12,246
Provision for credit losses	3,545	2,084	5,804	4,345
Non-interest expense	3,134	3,020	6,363	6,058
Income (Loss) from continuing operations before income taxes	121	1,122	1,381	1,843
Income tax provision (benefit)	30	265	329	437
Income (loss) from continuing operations, net of tax	91	857	1,052	1,406
Loans held for investment	153,895	142,491	153,895	142,491
Deposits	0	0	0	0
Operating segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income (loss)	2,025	2,269	4,036	4,629
Non-interest income	172	149	331	284
Total net revenue (loss)	2,197	2,418	4,367	4,913
Provision for credit losses	330	259	756	534
Non-interest expense	1,250	1,231	2,496	2,514
Income (Loss) from continuing operations before income taxes	617	928	1,115	1,865
Income tax provision (benefit)	146	219	263	440
Income (loss) from continuing operations, net of tax	471	709	852	1,425
Loans held for investment	75,663	77,280	75,663	77,280
Deposits	305,422	286,174	305,422	286,174
Operating segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income (loss)	609	632	1,208	1,280
Non-interest income	271	257	552	469
Total net revenue (loss)	880	889	1,760	1,749
Provision for credit losses	34	146	32	405
Non-interest expense	483	482	998	1,012
Income (Loss) from continuing operations before income taxes	363	261	730	332
Income tax provision (benefit)	85	61	172	78
Income (loss) from continuing operations, net of tax	278	200	558	254
Loans held for investment	88,628	91,552	88,628	91,552
Deposits	29,210	36,793	29,210	36,793
Other
Segment Reporting Information [Line Items]
Net interest income (loss)	(382)	(515)	(776)	(994)
Non-interest income	11	(6)	9	1
Total net revenue (loss)	(371)	(521)	(767)	(993)
Provision for credit losses	0	1	0	1
Non-interest expense	79	61	226	155
Income (Loss) from continuing operations before income taxes	(450)	(583)	(993)	(1,149)
Income tax provision (benefit)	(207)	(248)	(408)	(455)
Income (loss) from continuing operations, net of tax	(243)	(335)	(585)	(694)
Loans held for investment	0	0	0	0
Deposits	$ 16,810	$ 20,738	$ 16,810	$ 20,738