Loans - Consumer, Excluding Credit Card Loans, Other Consumer Impaired Loans and Loan Modifications (Details) - Consumer, excluding credit card - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Average impaired loans	$ 10,066	$ 12,609	$ 13,460
Total other consumer
Financing Receivable, Impaired [Line Items]
With an allowance	527	557
Without an allowance	31	35
Total impaired loans	558	592
Allowance for loan losses related to impaired loans	118	117
Unpaid principal balance of impaired loans	668	719
Impaired loans on nonaccrual status	449	456
Average impaired loans	566	599	$ 648
Troubled debt restructuring	384	442
Impaired loans on nonaccrual status	$ 275	$ 306