Fair Value Measurements (Details 5) (Debt Securities, USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Debt Securities
Amortized cost basis, unrealized gains and losses, and approximate fair values of investments in held-to-maturity securities
Cost Basis	$ 13	$ 33
Unrealized Gains	4	2
Fair Value	$ 17	$ 35

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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