Deposits (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deposits [Abstract]
Contractual maturities, time deposits, $100,000 or more, domestic, less than 3 months [Abstract] [Abstract]	$ 417
Contractual maturities, time deposits, $100,000 or more, domestic, between 3 and 6 months [Abstract]	401
Contractual maturities, time deposits, $100,000 or more, between 6 and 12 months [Abstract]	679
Contractual maturities, time deposits, $100,000 or more, after 12 months [Abstract] [Abstract]	364
Domestic time deposits under $100,000	1,400	$ 1,500
Domestic time deposits $100,000 and over	1,400	584
Foreign time deposits $100,000 and over		112
Deposit overdrafts reclassified as loan balances	$ 11	$ 14