Fair Value Measurements - Amounts Included in Earnings Attributable to Changes in Unrealized Gains and Losses Related to Recurring L3 Assets and Liabilites Still Held at Year End (Details) - 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]
Gain and losses included in earnings	$ (136)	$ (12)	$ (224)	$ (25)
Mortgage banking net revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain and losses included in earnings	(115)	(2)	(173)	23
Corporate banking revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain 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]
Gain and losses included in earnings	$ (22)	$ (10)	$ (52)	$ (49)