Business Segments and Revenue from Contracts with Customers - Segment Results and Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net interest income (loss)	$ 6,517	$ 5,743	$ 12,914	$ 11,565
Non-interest income (loss)	1,715	1,631	3,491	2,922
Total net revenue (loss)	8,232	7,374	16,405	14,487
Provision (benefit) for credit losses	1,085	(1,160)	1,762	(1,983)
Non-interest expense	4,583	3,966	9,134	7,706
Income from continuing operations before income taxes	2,564	4,568	5,509	8,764
Income tax provision	533	1,031	1,075	1,900
Income (loss) from continuing operations, net of tax	2,031	3,537	4,434	6,864
Total loans held for investment	296,384	249,597	296,384	249,597	$ 277,340
Total Deposits	307,885	306,308	307,885	306,308	$ 310,980
Uncollectible portion of billed finance charges and fees	211	175	403	355
Operating segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income (loss)	3,899	3,217	7,738	6,589
Non-interest income (loss)	1,410	1,253	2,868	2,282
Total net revenue (loss)	5,309	4,470	10,606	8,871
Provision (benefit) for credit losses	581	(635)	1,126	(1,127)
Non-interest expense	2,771	2,263	5,554	4,398
Income from continuing operations before income taxes	1,957	2,842	3,926	5,600
Income tax provision	466	672	935	1,325
Income (loss) from continuing operations, net of tax	1,491	2,170	2,991	4,275
Total loans held for investment	120,880	101,017	120,880	101,017
Total Deposits	0	0	0	0
Operating segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income (loss)	2,147	2,101	4,260	4,131
Non-interest income (loss)	96	144	201	285
Total net revenue (loss)	2,243	2,245	4,461	4,416
Provision (benefit) for credit losses	281	(306)	411	(432)
Non-interest expense	1,286	1,123	2,522	2,240
Income from continuing operations before income taxes	676	1,428	1,528	2,608
Income tax provision	160	337	362	615
Income (loss) from continuing operations, net of tax	516	1,091	1,166	1,993
Total loans held for investment	81,531	74,759	81,531	74,759
Total Deposits	255,904	251,155	255,904	251,155
Operating segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income (loss)	635	460	1,242	980
Non-interest income (loss)	272	257	549	497
Total net revenue (loss)	907	717	1,791	1,477
Provision (benefit) for credit losses	222	(219)	230	(422)
Non-interest expense	485	417	973	836
Income from continuing operations before income taxes	200	519	588	1,063
Income tax provision	48	123	140	251
Income (loss) from continuing operations, net of tax	152	396	448	812
Total loans held for investment	93,973	73,821	93,973	73,821
Total Deposits	38,844	42,973	38,844	42,973
Other
Segment Reporting Information [Line Items]
Net interest income (loss)	(164)	(35)	(326)	(135)
Non-interest income (loss)	(63)	(23)	(127)	(142)
Total net revenue (loss)	(227)	(58)	(453)	(277)
Provision (benefit) for credit losses	1	0	(5)	(2)
Non-interest expense	41	163	85	232
Income from continuing operations before income taxes	(269)	(221)	(533)	(507)
Income tax provision	(141)	(101)	(362)	(291)
Income (loss) from continuing operations, net of tax	(128)	(120)	(171)	(216)
Total loans held for investment	0	0	0	0
Total Deposits	$ 13,137	$ 12,180	$ 13,137	$ 12,180