Noninterest Revenue and Noninterest Expense - Components of Noninterest Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Noninterest Income (Expense) [Abstract]
Legal expense/(benefit)	$ 10	$ 20	$ (2)	$ 90
FDIC-related expense	$ 114	$ 349	$ 378	$ 1,100