Loans - Consumer, Excluding Credit Card Loans, PCI Delinquency Statistics (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 | Purchased Credit-Impaired, Home Equity Senior Lien
Loans and Leases Receivable Disclosure [Line Items]
Percentage of senior liens to total financing receivables	20.00%
Consumer, excluding credit card | Purchased Credit-Impaired, Home Equity Junior Lien, Excluding Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	713,000,000	736,000,000
Total 30 plus day delinquency rate	5.89%	8.83%
Consumer, excluding credit card | Purchased Credit-Impaired, Home Equity Junior Lien
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	13,827,000,000	13,851,000,000
Total 30 plus day delinquency rate	4.93%	6.55%
Consumer, excluding credit card | HELOC, Within the revolving period | Purchased Credit-Impaired, Home Equity Junior Lien, Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	8,373,000,000	8,972,000,000
Total 30 plus day delinquency rate	4.69%	6.42%
Home equity line of credit, open-ended revolving period	10 years
Consumer, excluding credit card | HELOCs, Beyond the revolving period | Purchased Credit-Impaired, Home Equity Junior Lien, Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	4,741,000,000	4,143,000,000
Total 30 plus day delinquency rate	5.21%	6.42%
Consumer, excluding credit card | 30–89 days past due | Purchased Credit-Impaired, Home Equity Junior Lien, Excluding Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	16,000,000	20,000,000
Consumer, excluding credit card | 30–89 days past due | Purchased Credit-Impaired, Home Equity Junior Lien
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	206,000,000	251,000,000
Consumer, excluding credit card | 30–89 days past due | HELOC, Within the revolving period | Purchased Credit-Impaired, Home Equity Junior Lien, Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	118,000,000	155,000,000
Consumer, excluding credit card | 30–89 days past due | HELOCs, Beyond the revolving period | Purchased Credit-Impaired, Home Equity Junior Lien, Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	72,000,000	76,000,000
Consumer, excluding credit card | 90–149 days past due | Purchased Credit-Impaired, Home Equity Junior Lien, Excluding Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	5,000,000	7,000,000
Consumer, excluding credit card | 90–149 days past due | Purchased Credit-Impaired, Home Equity Junior Lien
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	65,000,000	81,000,000
Consumer, excluding credit card | 90–149 days past due | HELOC, Within the revolving period | Purchased Credit-Impaired, Home Equity Junior Lien, Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	39,000,000	50,000,000
Consumer, excluding credit card | 90–149 days past due | HELOCs, Beyond the revolving period | Purchased Credit-Impaired, Home Equity Junior Lien, Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	21,000,000	24,000,000
Consumer, excluding credit card | 150 days past due | Purchased Credit-Impaired, Home Equity Junior Lien, Excluding Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	21,000,000	38,000,000
Consumer, excluding credit card | 150 days past due | Purchased Credit-Impaired, Home Equity Junior Lien
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	411,000,000	575,000,000
Consumer, excluding credit card | 150 days past due | HELOC, Within the revolving period | Purchased Credit-Impaired, Home Equity Junior Lien, Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	236,000,000	371,000,000
Consumer, excluding credit card | 150 days past due | HELOCs, Beyond the revolving period | Purchased Credit-Impaired, Home Equity Junior Lien, Lines of Credit
Loans and Leases Receivable Disclosure [Line Items]
Total retained loans	$ 154,000,000	$ 166,000,000