Loans - Consumer, Excluding Credit Card Loans, Delinquency Statistics Junior Lien Home Equity Loans (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 756,971,000,000	$ 747,508,000,000	$ 721,160,000,000
Consumer, excluding credit card
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	304,917,000,000	294,979,000,000	287,930,000,000
Consumer, excluding credit card | Home equity - junior lien
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	34,968,000,000	36,375,000,000
% of 30 days past due to total retained loans	2.10%	2.20%
Consumer, excluding credit card | Home equity junior lien, excluding lines of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	2,979,000,000	3,144,000,000
% of 30 days past due to total retained loans	2.99%	3.34%
Consumer, excluding credit card | 30–89 days past due | Home equity - junior lien
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	351,000,000	407,000,000
Consumer, excluding credit card | 30–89 days past due | Home equity junior lien, excluding lines of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	52,000,000	66,000,000
Consumer, excluding credit card | 90–149 days past due | Home equity - junior lien
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	118,000,000	126,000,000
Consumer, excluding credit card | 90–149 days past due | Home equity junior lien, excluding lines of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	17,000,000	20,000,000
Consumer, excluding credit card | 150 days past due | Home equity - junior lien
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	264,000,000	267,000,000
Consumer, excluding credit card | 150 days past due | Home equity junior lien, excluding lines of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	20,000,000	19,000,000
Consumer, excluding credit card | HELOC, Within the revolving period | Home equity line of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	23,335,000,000	25,252,000,000
% of 30 days past due to total retained loans	1.65%	1.75%
Home equity line of credit, open-ended revolving period	10 years
Home equity line of credit, amortization period	20 years
Consumer, excluding credit card | HELOC, Within the revolving period | 30–89 days past due | Home equity line of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	191,000,000	233,000,000
Consumer, excluding credit card | HELOC, Within the revolving period | 90–149 days past due | Home equity line of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	60,000,000	69,000,000
Consumer, excluding credit card | HELOC, Within the revolving period | 150 days past due | Home equity line of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	134,000,000	141,000,000
Consumer, excluding credit card | HELOCs, Beyond the revolving period | Home equity line of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	8,654,000,000	7,979,000,000
% of 30 days past due to total retained loans	2.99%	3.16%
Consumer, excluding credit card | HELOCs, Beyond the revolving period | 30–89 days past due | Home equity line of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	108,000,000	108,000,000
Consumer, excluding credit card | HELOCs, Beyond the revolving period | 90–149 days past due | Home equity line of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	41,000,000	37,000,000
Consumer, excluding credit card | HELOCs, Beyond the revolving period | 150 days past due | Home equity line of credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 110,000,000	$ 107,000,000