Business Segments and Revenue from Contracts with Customers - Segment Results and Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net interest income (loss)	$ 29,241	$ 27,114	$ 24,171
Non-interest income (loss)	7,546	7,136	6,264
Total net revenue (loss)	36,787	34,250	30,435
Provision for credit losses	10,426	5,847	(1,944)
Non-interest expense	20,316	19,163	16,570
Income (loss) from continuing operations before income taxes	6,045	9,240	15,809
Income tax provision (benefit)	1,158	1,880	3,415
Income (loss) from continuing operations, net of tax	4,887	7,360	12,394
Total loans held for investment		312,331	277,340
Deposits	348,413	332,992	310,980
Uncollectible portion of billed finance charges and fees	1,900	946	629
Operating segments | Credit Card
Segment Reporting Information [Line Items]
Net interest income (loss)	19,729	16,584	14,074
Non-interest income (loss)	5,940	5,771	4,806
Total net revenue (loss)	25,669	22,355	18,880
Provision for credit losses	8,651	4,265	(902)
Non-interest expense	12,490	11,627	9,621
Income (loss) from continuing operations before income taxes	4,528	6,463	10,161
Income tax provision (benefit)	1,071	1,536	2,403
Income (loss) from continuing operations, net of tax	3,457	4,927	7,758
Total loans held for investment	154,547	137,730	114,772
Deposits	0	0	0
Operating segments | Consumer Banking
Segment Reporting Information [Line Items]
Net interest income (loss)	8,713	8,965	8,448
Non-interest income (loss)	589	469	554
Total net revenue (loss)	9,302	9,434	9,002
Provision for credit losses	1,169	1,173	(521)
Non-interest expense	5,178	5,312	4,711
Income (loss) from continuing operations before income taxes	2,955	2,949	4,812
Income tax provision (benefit)	697	699	1,136
Income (loss) from continuing operations, net of tax	2,258	2,250	3,676
Total loans held for investment	75,437	79,925	77,646
Deposits	296,171	270,592	256,407
Operating segments | Commercial Banking
Segment Reporting Information [Line Items]
Net interest income (loss)	2,518	2,461	2,153
Non-interest income (loss)	1,002	1,129	1,148
Total net revenue (loss)	3,520	3,590	3,301
Provision for credit losses	605	415	(519)
Non-interest expense	2,011	2,070	1,815
Income (loss) from continuing operations before income taxes	904	1,105	2,005
Income tax provision (benefit)	213	262	473
Income (loss) from continuing operations, net of tax	691	843	1,532
Total loans held for investment	90,488	94,676	84,922
Deposits	32,712	40,808	44,809
Other
Segment Reporting Information [Line Items]
Net interest income (loss)	(1,719)	(896)	(504)
Non-interest income (loss)	15	(233)	(244)
Total net revenue (loss)	(1,704)	(1,129)	(748)
Provision for credit losses	1	(6)	(2)
Non-interest expense	637	154	423
Income (loss) from continuing operations before income taxes	(2,342)	(1,277)	(1,169)
Income tax provision (benefit)	(823)	(617)	(597)
Income (loss) from continuing operations, net of tax	(1,519)	(660)	(572)
Total loans held for investment	0	0	0
Deposits	$ 19,530	$ 21,592	$ 9,764