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Investments (Other Investment Portfolio by Strategy and the Remaining Commitment Amount Associated With Each Strategy) (Details) - USD ($) $ in Thousands | Jun. 30, 2015 | Dec. 31, 2014
--- | --- | ---
Carrying Value | $ 85,420 | $ 99,203
Other Investments [Member] |  |
Carrying Value | 85,420 | 99,203
Remaining Commitment | 64,530 |
Alternative Investments [Member] |  |
Carrying Value | 74,188 | 92,968
Remaining Commitment | 62,261 |
Secondary Private Equity Member | Alternative Investments [Member] |  |
Carrying Value | 18,997 | 21,807
Remaining Commitment | 7,072 |
Private Equity [Member] | Alternative Investments [Member] |  |
Carrying Value | 16,027 | 20,126
Remaining Commitment | 8,823 |
Energy Power Generation [Member] | Alternative Investments [Member] |  |
Carrying Value | 9,662 | 14,445
Remaining Commitment | 19,610 |
Real Estate Strategy [Member] | Alternative Investments [Member] |  |
Carrying Value | 8,242 | 11,452
Remaining Commitment | 9,975 |
Mezzanine Financing [Member] | Alternative Investments [Member] |  |
Carrying Value | 7,563 | 9,853
Remaining Commitment | 13,383 |
Distressed debt [Member] | Alternative Investments [Member] |  |
Carrying Value | 7,000 | 8,679
Remaining Commitment | 3,048 |
Venture Capital [Member] | Alternative Investments [Member] |  |
Carrying Value | 6,697 | 6,606
Remaining Commitment | 350 |
Other Securities [Member] |  |
Carrying Value | 11,232 | $ 6,235
Remaining Commitment | $ 2,269 |

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