Loans - Credit Card Portfolio - Loans Modifications (Details) (Credit card, Credit Card Loan, USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 loan_payment	Jun. 30, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted-average interest rate of loans with interest rate reductions – before TDR	15.05%	15.38%	15.04%	15.44%
Weighted-average interest rate of loans with interest rate reductions – after TDR	4.33%	4.27%	4.36%	4.88%
Balance of loans that redefaulted within one year of permanent modification	$ 29,000,000	$ 41,000,000	$ 63,000,000	$ 85,000,000
Number of payments past due for deemed payment default			2
Rate of default for modified loans, estimated weighted average			29.17%		30.72%
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of years before payment default under a modified loan			1 year
Total new enrollments
Accounts, Notes, Loans and Financing Receivable [Line Items]
New TDRs	$ 193,000,000	$ 288,000,000	$ 426,000,000	$ 627,000,000