Deposits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total deposits	$ 118,702	$ 129,248	$ 118,579
Deposits held for sale	673	0
Time Deposits, $250,000 or More [Abstract]
Time Deposits, $250,000 or More	14,504	18,644
Time Deposits, Fiscal Year Maturity [Abstract]
0-90 days	9,065
91-180 days	2,677
181-365 days	3,315
2018	15,057
2019	1,451
2020	797
2021	1,212
2022	1,051
Thereafter	3,603
Time deposits	23,171
Overdraft deposits	321	442
Domestic Deposits [Member]
Time Deposits, $250,000 or More [Abstract]
Time Deposits, $250,000 or More	13,875	14,419
Time Deposits, Fiscal Year Maturity [Abstract]
0-90 days	8,538
91-180 days	2,553
181-365 days	3,315
2018	14,406
2019	1,450
2020	796
2021	1,212
2022	1,051
Thereafter	3,603
Time deposits	22,518
Foreign Deposits [Member]
Time Deposits, $250,000 or More [Abstract]
Time Deposits, $250,000 or More	629	4,225
Time Deposits, Fiscal Year Maturity [Abstract]
0-90 days	527
91-180 days	124
181-365 days	0
2018	651
2019	1
2020	1
2021	0
2022	0
Thereafter	0
Time deposits	653
Deposits [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Deposits at fair value	7,693	7,526
Other Expense [Member]
Time Deposits, Fiscal Year Maturity [Abstract]
FDIC assessment fees	$ 138	$ 168	$ 120