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Fair Value Measurements (Narrative) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2011 | Dec. 31, 2010
Fair Value Measurement [Line Items] |  |
Percentage of unadjusted fair values obtained | 98.00% |
Percentage of specific unadjusted broker quotes obtained | 2.00% |
Transfers between Levels 1, 2, and 3 of the fair value hierarchy | $ 0 | $ 0
Changes in financial assets related to liquidity assumptions | $ 10 | $ 0
Minimum [Member] |  |
Fair Value Measurement [Line Items] |  |
Number of knowledgeable outside security brokers consulted to determine fair value | 1 |

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- Definition Fair value, assets measured on recurring basis, change in financial assets related to liquidity assumptions + References No definition available. + Details
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- Details
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- Definition The amount of the transfers of assets or liabilities into or out of Levels 1, 2, and 3. + References No definition available. + Details
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- Definition Number of knowledgeable outside security brokers consulted to determine fair value. + References No definition available. + Details
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- Definition Percentage of specific unadjusted broker quotes obtained + References No definition available. + Details
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- Definition Percentage of Unadjusted Fair Values Obtained. + References No definition available. + Details
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