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Investments (Schedule of Proceeds, Recognized Gains and Losses and Net Unrealized Gains and Losses) (Details) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | |
|---|---|---|
|
Mar. 31, 2015
|
Mar. 31, 2014
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| Investments, Debt and Equity Securities [Abstract] | ||
| Proceeds from the sales of available-for-sale investment securities | $ 899 | $ 1,220 |
| Gain on sales of available-for-sale investment securities | 8 | 4 |
| Net unrealized gain recorded in other comprehensive income, before-tax | 0 | 3 |
| Net unrealized gain recorded in other comprehensive income, after-tax | $ 0 | $ 2 |