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Investments (Other Investment Portfolio by Strategy and the Remaining Commitment Amount Associated With Each Strategy) (Details) - USD ($) $ in Thousands | Sep. 30, 2015 | Dec. 31, 2014
--- | --- | ---
Carrying Value | $ 85,146 | $ 99,203
Alternative Investments [Member] |  |
Carrying Value | 74,168 | 92,968
Remaining Commitment | 74,278 |
Other Investments [Member] |  |
Carrying Value | 85,146 | 99,203
Remaining Commitment | 76,547 |
Secondary Private Equity [Member] | Alternative Investments [Member] |  |
Carrying Value | 17,503 | 21,807
Remaining Commitment | 7,095 |
Private Equity [Member] | Alternative Investments [Member] |  |
Carrying Value | 15,792 | 20,126
Remaining Commitment | 23,826 |
Energy/Power Generation [Member] | Alternative Investments [Member] |  |
Carrying Value | 11,643 | 14,445
Remaining Commitment | 16,857 |
Real Estate [Member] | Alternative Investments [Member] |  |
Carrying Value | 8,854 | 11,452
Remaining Commitment | 9,919 |
Mezzanine Financing [Member] | Alternative Investments [Member] |  |
Carrying Value | 6,948 | 9,853
Remaining Commitment | 13,383 |
Distressed debt [Member] | Alternative Investments [Member] |  |
Carrying Value | 6,889 | 8,679
Remaining Commitment | 3,048 |
Venture Capital [Member] | Alternative Investments [Member] |  |
Carrying Value | 6,539 | 6,606
Remaining Commitment | 150 |
Other Securities [Member] |  |
Carrying Value | 10,978 | $ 6,235
Remaining Commitment | $ 2,269 |

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