Noninterest Income - Gains and Losses on Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other Income and Expenses [Abstract]
Gains on exercises, net	$ 91	$ 24	$ 381	$ 59
Terminations	(1)	0	(2)	(1)
Changes in fair value, net	57	30	112	36
Gains on equity warrant assets, net	$ 147	$ 54	$ 491	$ 94