Business Segments and Revenue from Contracts with Customers - Segment Results and Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net interest income (loss)	$ 7,488	$ 7,186
Non-interest income (loss)	1,914	1,717
Total net revenue (loss)	9,402	8,903
Provision for credit losses	2,683	2,795
Non-interest expense	5,137	4,945
Income (loss) from continuing operations before income taxes	1,582	1,163
Income tax provision (benefit)	302	203
Income (loss) from continuing operations, net of tax	1,280	960
Loans held for investment	315,154	308,836
Deposits	350,969	349,827	$ 348,413
Uncollectible portion of billed finance charges and fees	630	405
Operating segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income (loss)	5,272	4,657
Non-interest income (loss)	1,476	1,363
Total net revenue (loss)	6,748	6,020
Provision for credit losses	2,259	2,261
Non-interest expense	3,229	3,038
Income (loss) from continuing operations before income taxes	1,260	721
Income tax provision (benefit)	299	172
Income (loss) from continuing operations, net of tax	961	549
Loans held for investment	150,594	137,142
Deposits	0	0
Operating segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income (loss)	2,011	2,360
Non-interest income (loss)	159	135
Total net revenue (loss)	2,170	2,495
Provision for credit losses	426	275
Non-interest expense	1,246	1,283
Income (loss) from continuing operations before income taxes	498	937
Income tax provision (benefit)	117	221
Income (loss) from continuing operations, net of tax	381	716
Loans held for investment	75,099	78,151
Deposits	300,806	291,163
Operating segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income (loss)	599	648
Non-interest income (loss)	281	212
Total net revenue (loss)	880	860
Provision for credit losses	(2)	259
Non-interest expense	515	530
Income (loss) from continuing operations before income taxes	367	71
Income tax provision (benefit)	87	17
Income (loss) from continuing operations, net of tax	280	54
Loans held for investment	89,461	93,543
Deposits	31,082	38,380
Other
Segment Reporting Information [Line Items]
Net interest income (loss)	(394)	(479)
Non-interest income (loss)	(2)	7
Total net revenue (loss)	(396)	(472)
Provision for credit losses	0	0
Non-interest expense	147	94
Income (loss) from continuing operations before income taxes	(543)	(566)
Income tax provision (benefit)	(201)	(207)
Income (loss) from continuing operations, net of tax	(342)	(359)
Loans held for investment	0	0
Deposits	$ 19,081	$ 20,284