Business Segments and Revenue from Contracts with Customers - Segment Results and Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net interest income (loss)	$ 6,397	$ 5,822
Non-interest income (loss)	1,776	1,291
Total net revenue (loss)	8,173	7,113
Amounts expected to become due from (to) partners which reduced (increased) provision for credit losses	677	(823)
Non-interest expense	4,551	3,740
Income from continuing operations before income taxes	2,945	4,196
Income tax provision	542	869
Income (loss) from continuing operations, net of tax	2,403	3,327
Total loans held for investment	280,466	243,131	$ 277,340
Total Deposits	313,429	310,328	$ 310,980
Uncollectible portion of billed finance charges and fees	192	180
Operating segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income (loss)	3,839	3,372
Non-interest income (loss)	1,458	1,029
Total net revenue (loss)	5,297	4,401
Amounts expected to become due from (to) partners which reduced (increased) provision for credit losses	545	(492)
Non-interest expense	2,783	2,135
Income from continuing operations before income taxes	1,969	2,758
Income tax provision	469	653
Income (loss) from continuing operations, net of tax	1,500	2,105
Total loans held for investment	113,962	99,127
Total Deposits	0	0
Operating segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income (loss)	2,113	2,030
Non-interest income (loss)	105	141
Total net revenue (loss)	2,218	2,171
Amounts expected to become due from (to) partners which reduced (increased) provision for credit losses	130	(126)
Non-interest expense	1,236	1,117
Income from continuing operations before income taxes	852	1,180
Income tax provision	202	278
Income (loss) from continuing operations, net of tax	650	902
Total loans held for investment	80,330	70,202
Total Deposits	258,359	254,001
Operating segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income (loss)	607	520
Non-interest income (loss)	277	240
Total net revenue (loss)	884	760
Amounts expected to become due from (to) partners which reduced (increased) provision for credit losses	8	(203)
Non-interest expense	488	419
Income from continuing operations before income taxes	388	544
Income tax provision	92	128
Income (loss) from continuing operations, net of tax	296	416
Total loans held for investment	86,174	73,802
Total Deposits	45,232	41,552
Other
Segment Reporting Information [Line Items]
Net interest income (loss)	(162)	(100)
Non-interest income (loss)	(64)	(119)
Total net revenue (loss)	(226)	(219)
Amounts expected to become due from (to) partners which reduced (increased) provision for credit losses	(6)	(2)
Non-interest expense	44	69
Income from continuing operations before income taxes	(264)	(286)
Income tax provision	(221)	(190)
Income (loss) from continuing operations, net of tax	(43)	(96)
Total loans held for investment	0	0
Total Deposits	$ 9,838	$ 14,775