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		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains and losses included in earnings	$ (131)	$ (8)	$ (370)	$ (9)
Mortgage banking net revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains and losses included in earnings	(121)	9	(309)	56
Corporate banking revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains and losses included in earnings	1	0	2	1
Other noninterest income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gains and losses included in earnings	$ (11)	$ (17)	$ (63)	$ (66)