Stockholders' Equity - Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Before Tax
Net unrealized gains (losses) on securities available for sale	$ 66	$ 292	$ (1,446)	$ 1,902
Net unrealized gains (losses) on hedging relationships	(68)	76	(834)	1,884
Foreign currency translation adjustments	4	20	17	(1)
Other	0	0	(1)	0
Other comprehensive income (loss), before tax	2	388	(2,264)	3,785
Provision (Benefit)
Net unrealized gains (losses) on securities available for sale	15	70	(349)	456
Net unrealized gains (losses) on hedging relationships	(17)	19	(202)	453
Foreign currency translation adjustments	(5)	(3)	(11)	43
Other	0	0	0	0
Other comprehensive income (loss), provision (benefit)	(7)	86	(562)	952
After Tax
Net unrealized gains (losses) on securities available for sale	51	222	(1,097)	1,446
Net unrealized gains (losses) on hedging relationships	(51)	57	(632)	1,431
Foreign currency translation adjustments	9	23	28	(44)
Other	0	0	(1)	0
Other comprehensive income (loss), net of tax	$ 9	$ 302	$ (1,702)	$ 2,833

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