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Investments (Details 5) (USD $) In Thousands, unless otherwise specified | Jun. 30, 2012 | Dec. 31, 2011
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Cash and securities pledged directly from the investment portfolio [Member] |  |
Schedule of sources of collateral received or held and how that collateral was pledged |  |
Fair Value of Cash and Underlying Securities | $ 776,523 | $ 874,987
Fair Value of Cash and Securities Pledged to Investment and Repurchase Agreement Counterparties | 461,408 | 564,036
Fair Value of Cash and Securities Pledged to Derivative Counterparties | 315,115 | 310,951
Cash and securities pledged from its derivative counterparties [Member] |  |
Schedule of sources of collateral received or held and how that collateral was pledged |  |
Fair Value of Cash and Underlying Securities |  |
Fair Value of Cash and Securities Pledged to Investment and Repurchase Agreement Counterparties |  |
Fair Value of Cash and Securities Pledged to Derivative Counterparties |  |

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- Definition Fair value of cash and securities pledged to investment and repurchase agreement counterparties. + References No definition available. + Details
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- Details
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