Deposits and Borrowings - Deposits and Short-term Borrowings (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deposits:
Non-interest-bearing deposits	$ 25,502	$ 25,847
Interest-bearing deposits	211,266	191,874
Total deposits	236,768	217,721	$ 205,548
Short-term Debt [Line Items]
Short-term borrowings	992	981
Federal funds purchased and securities loaned or sold under agreements to repurchase
Short-term Debt [Line Items]
Short-term borrowings	$ 992	$ 981