Fair Value Measurements - Amounts Included in Earnings for Assets and Liabilites Measured at Recurring L3 Fair Value (Details) - Fair Value, Inputs, Level 3 - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains and losses included in earnings	$ (150)	$ (2)	$ (240)	$ (1)
Mortgage banking net revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains and losses included in earnings	(129)	8	(189)	47
Corporate banking revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains and losses included in earnings	1	0	1	1
Other noninterest income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains and losses included in earnings	$ (22)	$ (10)	$ (52)	$ (49)