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Investments - Summary of Net Investment Income (Detail) - Successor [Member] - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2016 | Mar. 31, 2015
Investment [Line Items] |  |
Fixed income securities | $ 59,426 | $ 65,585
Short-term investments | 553 | 42
Loans | 106 | 132
Investment expense | (2,103) | (2,427)
Securities available-for-sale and short-term | 57,982 | 63,332
Other investments | 2,839 | 9,651
Total net investment income | 60,821 | 72,983
Gains (losses) on securities held as of reporting date [Member] |  |
Investment [Line Items] |  |
Net Realized and Unrealized Gain (Loss) on Trading Securities | 1,707 | 7,819
Trading Securities, Realized Gain (Loss) | 406 | 1,564
Other investments | $ 1,301 | $ 6,255

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