Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Allowance for credit losses	$ 2,657	$ 3,649
Rewards programs	825	711
Net operating loss and tax credit carryforwards	367	314
Lease liabilities	345	396
Compensation and employee benefits	337	306
Partnership investments	238	237
Other assets	359	418
Subtotal	5,128	6,031
Valuation allowance	(355)	(296)
Total deferred tax assets	4,773	5,735
Deferred tax liabilities:
Original issue discount	361	481
Right-of-use assets	284	342
Partnership investments	128	142
Mortgage servicing rights	88	73
Security and loan valuations	49	805
Net unrealized gains on derivatives	32	387
Other liabilities	123	179
Total deferred tax liabilities	1,065	2,409
Net deferred tax assets	$ 3,708	$ 3,326