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		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]
Gain and losses included in earnings	$ (118)	$ (19)	$ (368)	$ (54)
Mortgage banking net revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain and losses included in earnings	(109)	(2)	(307)	11
Corporate banking revenue
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain and losses included in earnings	2	0	2	1
Other noninterest income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain and losses included in earnings	$ (11)	$ (17)	$ (63)	$ (66)