Loans and Allowance for Loan Losses (Details 4) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Nonaccrual loans
Nonaccrual loans	$ 569	$ 689
Troubled debt restructured loans that continue to accrue interest	336	215
Troubled debt restructured nonaccrual loans (included in the total nonaccrual loans above)	301	384
Commercial portfolio
Nonaccrual loans
Nonaccrual loans	433	489
Commercial portfolio | Commercial and industrial
Nonaccrual loans
Nonaccrual loans	400	458
Commercial portfolio | Commercial mortgage
Nonaccrual loans
Nonaccrual loans	33	31
Consumer portfolio
Nonaccrual loans
Nonaccrual loans	136	200
Consumer portfolio | Residential mortgage
Nonaccrual loans
Nonaccrual loans	110	171
Consumer portfolio | Home equity and other consumer loans
Nonaccrual loans
Nonaccrual loans	$ 26	$ 29