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Fair Value Measurements - Information about Valuation Inputs for Fixed Income Securities Classified as Level 3 (Detail) - Successor [Member] - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2016 | Dec. 31, 2015
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Available-for-sale Securities | $ 6,151,939 | $ 5,334,120
Asset-backed Securities [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Coupon rate | 5.96% |
Fair Value Inputs Maturity | 18 years 3 months 20 days |
Yield | 12.25% |
Variable Interest Entity, Primary Beneficiary [Member] | United States Transactions [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Coupon rate | 5.88% | 5.88%
Fair Value Inputs Maturity | 21 years 6 months 23 days | 21 years 9 months 23 days
Yield | 7.50% | 9.14%
Fair Value, Inputs, Level 3 [Member] | Corporate Obligations [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Available-for-sale Securities | $ 0 | $ 0
Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Available-for-sale Securities | 71,786 | 0
Fair Value, Inputs, Level 3 [Member] | Variable Interest Entity, Primary Beneficiary [Member] | Corporate Obligations [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Available-for-sale Securities | $ 2,622,724 | $ 2,588,556

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