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Investments (Other Investment Portfolio by Strategy and the Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy) (Details) - USD ($) $ in Thousands | Mar. 31, 2016 | Dec. 31, 2015
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Carrying Value | $ 80,916 | $ 77,842
Alternative Investments [Member] |  |
Carrying Value | 71,209 | 67,834
Remaining Commitment | 82,438 | 71,153
Maximum Exposure to Loss | 153,647 | 138,987
Other Investments [Member] |  |
Carrying Value | 80,916 | 77,842
Remaining Commitment | 89,288 | 74,353
Maximum Exposure to Loss | 170,204 | 152,195
Private Equity [Member] | Alternative Investments [Member] |  |
Carrying Value | 32,478 | 35,088
Remaining Commitment | 28,750 | 30,204
Maximum Exposure to Loss | 61,228 | 65,292
Private Credit [Member] | Alternative Investments [Member] |  |
Carrying Value | 21,939 | 13,246
Remaining Commitment | 25,129 | 15,129
Maximum Exposure to Loss | 47,068 | 28,375
Real Assets [Member] | Alternative Investments [Member] |  |
Carrying Value | 16,792 | 19,500
Remaining Commitment | 28,559 | 25,820
Maximum Exposure to Loss | 45,351 | 45,320
Other Securities [Member] |  |
Carrying Value | 9,707 | 10,008
Remaining Commitment | 6,850 | 3,200
Maximum Exposure to Loss | $ 16,557 | $ 13,208

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