Noninterest Revenue and Noninterest Expense - Components of Noninterest Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Noninterest Income (Expense) [Abstract]
Legal expense/(benefit)	$ 72	$ (35)	$ (317)
FDIC-related expense	$ 1,239	$ 1,492	$ 1,296