Noninterest Income - Gains and Losses on Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Other Income and Expenses [Abstract]
Gains on exercises, net	$ 78	$ 9	$ 251	$ 33
Terminations	(1)	0	(1)	(1)
Changes in fair value, net	45	18	94	8
Gains on equity warrant assets, net	$ 122	$ 27	$ 344	$ 40