Loans - Consumer, Excluding Credit Card Loan Portfolio, Impaired Loans (Details) - Consumer, excluding credit card $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) payment	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Impaired loans
Loans modified subsequent to repurchase from Ginnie Mae	$ 3,300		$ 4,100
TDRs less than 90 days past due	1,900		2,000
Total residential real estate – excluding PCI
Impaired loans
With an allowance	4,418		4,523
Without an allowance	2,077		2,054
Total impaired loans	6,495		6,577
Allowance for loan losses related to impaired loans	81		133
Unpaid principal balance of impaired loans	9,554		9,673
Impaired loans on nonaccrual status	2,416		2,414
Average impaired loans	6,537	$ 7,731
Interest income on impaired loans	92	102
Interest income on impaired loans on a cash basis	$ 38	40
Number of payments under modified terms to recognize interest on cash basis | payment	6
Residential mortgage
Impaired loans
With an allowance	$ 3,296		3,381
Without an allowance	1,203		1,184
Total impaired loans	4,499		4,565
Allowance for loan losses related to impaired loans	66		88
Unpaid principal balance of impaired loans	6,120		6,207
Impaired loans on nonaccrual status	1,456		1,459
Average impaired loans	4,536	5,608
Interest income on impaired loans	59	70
Interest income on impaired loans on a cash basis	$ 17	19
Residential mortgage | Permanent Modification
Impaired loans
Rate of default for modified loans, estimated weighted average	12.00%
Home equity
Impaired loans
With an allowance	$ 1,122		1,142
Without an allowance	874		870
Total impaired loans	1,996		2,012
Allowance for loan losses related to impaired loans	15		45
Unpaid principal balance of impaired loans	3,434		3,466
Impaired loans on nonaccrual status	960		$ 955
Average impaired loans	2,001	2,123
Interest income on impaired loans	33	32
Interest income on impaired loans on a cash basis	$ 21	$ 21
Home equity | Permanent Modification
Impaired loans
Rate of default for modified loans, estimated weighted average	8.00%