Loan Receivables (Schedule of Troubled Debt Restructurings That Subsequently Defaulted) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
accounts
Mar. 31, 2014
accounts
Financing Receivable, Modifications [Line Items]    
Amount of missed payments after which a customer defaults from a modification program (in payments) 2  
Total Other Loans [Member] | Private Student Loans [Member]    
Financing Receivable, Modifications [Line Items]    
Delinquency days to default (in days) 60 days  
Internal Programs [Member] | Credit Card Loans [Member]    
Financing Receivable, Modifications [Line Items]    
Troubled debt restructurings that subsequently defaulted, number of accounts (in accounts) 3,176 [1],[2] 2,331 [1],[2]
Troubled debt restructurings that subsequently defaulted, aggregated outstanding balances upon default $ 20 [1],[2] $ 14 [1],[2]
External Programs [Member] | Credit Card Loans [Member]    
Financing Receivable, Modifications [Line Items]    
Troubled debt restructurings that subsequently defaulted, number of accounts (in accounts) 1,643 [1],[2] 1,881 [1],[2]
Troubled debt restructurings that subsequently defaulted, aggregated outstanding balances upon default 7 [1],[2] 8 [1],[2]
Internal And External Loan Modification Programs [Member] | Total Other Loans [Member] | Personal Loans [Member]    
Financing Receivable, Modifications [Line Items]    
Troubled debt restructurings that subsequently defaulted, number of accounts (in accounts) 151 [1] 106 [1]
Troubled debt restructurings that subsequently defaulted, aggregated outstanding balances upon default 2 [1] 1 [1]
Entity Loan Modification Program [Member] | Total Other Loans [Member] | Private Student Loans [Member]    
Financing Receivable, Modifications [Line Items]    
Troubled debt restructurings that subsequently defaulted, number of accounts (in accounts) 305 [3] 311 [3]
Troubled debt restructurings that subsequently defaulted, aggregated outstanding balances upon default $ 4 [3] $ 5 [3]
[1] A customer defaults from a modification program after two consecutive missed payments.
[2] The outstanding balance upon default is the loan balance at the end of the month prior to default. Terms revert back to the pre-modification terms for customers who default from a temporary program and charging privileges remain revoked in most cases.
[3] Student loan defaults have been defined as loans that are 60 or more days delinquent.