Commitments, Contingencies and Guarantees (Schedule of Maximum Potential Counterparty Exposures Related to Settlement Guarantees) (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Merchant Guarantee [Member] | Diners Club [Member]  
Guarantor Obligations [Line Items]  
Maximum potential counterparty exposures to settlement guarantees $ 107
ATM Guarantee [Member] | PULSE [Member]  
Guarantor Obligations [Line Items]  
Maximum potential counterparty exposures to settlement guarantees $ 1