Stockholders' Equity - Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Before Tax
Net unrealized gains (losses) on securities available for sale	$ (2,486)	$ 1,659	$ 855
Net unrealized gains (losses) on hedging relationships	(1,640)	1,329	1,016
Foreign currency translation adjustments	17	56	54
Net changes in securities held to maturity	0	0	36
Other	4	4	17
Other comprehensive income (loss), before tax	(4,105)	3,048	1,978
Provision (Benefit)
Net unrealized gains (losses) on securities available for sale	(597)	400	205
Net unrealized gains (losses) on hedging relationships	(396)	321	244
Foreign currency translation adjustments	7	(20)	(16)
Net changes in securities held to maturity	0	0	10
Other	1	1	4
Other comprehensive income (loss), provision (benefit)	(985)	702	447
After Tax
Net unrealized gains (losses) on securities available for sale	(1,889)	1,259	650
Net unrealized gains (losses) on hedging relationships	(1,244)	1,008	772
Foreign currency translation adjustments	10	76	70
Net changes in securities held to maturity	0	0	26
Other	3	3	13
Other comprehensive income (loss), net of tax	$ (3,120)	$ 2,346	$ 1,531