Fair Value Measurements - Total Gains and Losses Included in Earnings for Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) - Level 3 - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Gains and losses included in earnings	$ (18)	$ (150)	$ (311)	$ (240)
Mortgage banking net revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Gains and losses included in earnings	10	(129)	(261)	(189)
Commercial banking revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Gains and losses included in earnings	1	1	1	1
Other noninterest income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Gains and losses included in earnings	$ (29)	$ (22)	$ (51)	$ (52)