Fair Value Measurements (Details 5) - Debt Securities - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Amortized cost basis, unrealized gains and losses, and approximate fair values of investments in held-to-maturity securities
Cost Basis	$ 10	$ 13
Unrecognized Gains	2	4
Fair Value	$ 12	$ 17

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

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