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Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2016 | Dec. 31, 2015
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Other Investments | $ 391,075 | $ 285,261
Credit valuation adjustment included in fair value of credit derivative liabilities | 2,761 | 10,124
Credit valuation adjustment included in fair value of derivative liabilities other than credit derivatives | $ 74,587 | 78,728
Percentage of CDS gross par outstanding using internally estimated reference obligation prices in determination of fair value | 0.00% |
Percentage of CDS liability using internally estimated reference obligation prices in determination of fair value | 0.00% |
Additional basis point fee need to receive for issuing a CDS on obligation | 0.05% |
Additional basis points fee increase on change of reference obligation spread | 0.15% |
Revised relative change ratio of CDS fee to cash market spread | 73.20% |
Estimated remaining life | 8 years |
Notional outstanding | $ 820,988 | 970,883
Derivative liabilities | $ 16,700 | $ 34,543
Credit Derivatives [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
CVA percentage | 14.20% | 22.70%
Minimum [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Basis point fee received for issuing a CDS on reference obligation base fee | 0.20% |
Credit spread of reference obligation of a base transaction | 0.80% |
Relative change ratio of CDS fee to cash market spread | 25.00% |
Maximum [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Basis point fee received for issuing a CDS on reference obligation hypothetical fee | 0.25% |
Relative change ratio of CDS fee to cash market spread | 35.00% |
Credit spread of reference obligation of revised transaction | 1.00% |
Internal Credit Rating [Member] | Minimum [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Revised relative change ratio of CDS fee to cash market spread | 33.00% |
Internal Credit Rating [Member] | Maximum [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Full relative change ratio of CDS fee to cash market spread | 100.00% |
Successor [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Notional outstanding | $ 820,988 | $ 970,883
Weighted average discounted rate of estimated future premium payments to be paid by the VIEs | 2.40% | 2.70%
Available-for-sale Securities | $ 6,186,101 | $ 5,334,120
Successor [Member] | Level 3 [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Other Investments | $ 12,339 | $ 12,834
Successor [Member] | Fixed Income Securities [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Percentage of investment portfolio valued using dealer quotes | 7.00% | 9.00%
Percentage of investment portfolio valued using external pricing services | 81.00% | 82.00%
Percentage of investment portfolio valued using internal valuation models | 12.00% | 9.00%
PercentageofInvestedPortfiliowhereProjectedCashFlowsConsistSolelyofDeferredAmountsandInterest | 11.00% | 9.00%
Successor [Member] | U.S. Agency Obligations [Member] | Level 3 [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Available-for-sale Securities | $ 0 | $ 0
Successor [Member] | Residential Mortgage-Backed Securities [Member] | Level 3 [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Available-for-sale Securities | 679,575 | 488,884
Successor [Member] | Corporate Obligations [Member] | Level 3 [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Available-for-sale Securities | 0 | 0
Successor [Member] | Collateralized Debt Obligations [Member] | Level 3 [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Available-for-sale Securities | $ 0 | $ 0
Variable Interest Entities [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Weighted average discounted rate of estimated future premium payments to be paid by the VIEs | 3.30% | 4.40%
Other Contracts [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Fair Value Input Weighted Average Credit Derivative Quote As Percentage Of Notional |  | 1.00%
Fair Value Input Weighted Average Credit Rating |  | A+
CVA percentage |  | 0.09%
Notional outstanding |  | $ 58,482
Fair Value Input Weighted Average Life |  | 2 months
Variable Interest Entity, Primary Beneficiary [Member] | Successor [Member] | Corporate Obligations [Member] | Level 3 [Member] |  |
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items] |  |
Available-for-sale Securities | $ 2,828,685 | $ 2,588,556

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