Investments (Schedule of Amortized Cost, Gross Unrealized Gains and Gross Unrealized Losses and Fair Value) (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Investment Holdings [Line Items]    
Available-for-sale investment securities, amortized cost $ 2,626 [1] $ 3,811 [1]
Available-for-sale investment securities, gross unrealized gains 37 [1] 37 [1]
Available-for-sale investment securities, gross unrealized losses 0 [1] (1) [1]
Available-for-sale investment securities, fair value 2,663 [1] 3,847 [1]
Held-to-maturity investment securities, amortized cost 115 [2] 102 [2]
Held-to-maturity investment securities, gross unrealized gains 2 [2] 2 [2]
Held-to-maturity investment securities, gross unrealized losses 0 [2] 0 [2]
Held-to-maturity investment securities, fair value 117 [2] 104 [2]
U.S. Treasury Securities [Member]    
Investment Holdings [Line Items]    
Available-for-sale investment securities, amortized cost 600 [1] 1,317 [1]
Available-for-sale investment securities, gross unrealized gains 7 [1] 12 [1]
Available-for-sale investment securities, gross unrealized losses 0 [1] 0 [1]
Available-for-sale investment securities, fair value 607 [1] 1,329 [1]
Held-to-maturity investment securities, amortized cost 1 [2],[3] 1 [2],[3]
Held-to-maturity investment securities, gross unrealized gains 0 [2],[3] 0 [2],[3]
Held-to-maturity investment securities, gross unrealized losses 0 [2],[3] 0 [2],[3]
Held-to-maturity investment securities, fair value 1 [2],[3] 1 [2],[3]
U.S. Government Agency Securities [Member]    
Investment Holdings [Line Items]    
Available-for-sale investment securities, amortized cost 620 [1] 1,021 [1]
Available-for-sale investment securities, gross unrealized gains 8 [1] 12 [1]
Available-for-sale investment securities, gross unrealized losses 0 [1] 0 [1]
Available-for-sale investment securities, fair value 628 [1] 1,033 [1]
Residential Mortgage-Backed Securities - Agency [Member]    
Investment Holdings [Line Items]    
Available-for-sale investment securities, amortized cost 1,406 [1] 1,473 [1]
Available-for-sale investment securities, gross unrealized gains 22 [1] 13 [1]
Available-for-sale investment securities, gross unrealized losses 0 [1] (1) [1]
Available-for-sale investment securities, fair value 1,428 [1] 1,485 [1]
Held-to-maturity investment securities, amortized cost 104 [2],[4] 91 [2],[4]
Held-to-maturity investment securities, gross unrealized gains 2 [2],[4] 2 [2],[4]
Held-to-maturity investment securities, gross unrealized losses 0 [2],[4] 0 [2],[4]
Held-to-maturity investment securities, fair value 106 [2],[4] 93 [2],[4]
States and Political Subdivisions of States [Member]    
Investment Holdings [Line Items]    
Held-to-maturity investment securities, amortized cost 10 [2] 10 [2]
Held-to-maturity investment securities, gross unrealized gains 0 [2] 0 [2]
Held-to-maturity investment securities, gross unrealized losses 0 [2] 0 [2]
Held-to-maturity investment securities, fair value $ 10 [2] $ 10 [2]
[1] Available-for-sale investment securities are reported at fair value.
[2] Held-to-maturity investment securities are reported at amortized cost.
[3] Amount represents securities pledged as collateral to a government-related merchant for which transaction settlement occurs beyond the normal 24-hour period.
[4] Amounts represent residential mortgage-backed securities that were classified as held-to-maturity as they were entered into as a part of the Company's community reinvestment initiatives.