v3.8.0.1

Fair Value of Financial Instruments - Fair Value Hierarchy (Details) $ in Thousands | Sep. 30, 2017 USD ($) security | Dec. 31, 2016 USD ($) security
--- | --- | ---
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Assets, number of securities priced for fair value | security | 3 | 3
Other investments | $ 7,041 | $ 13,060
Partnership Interest [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Other investments | 5,541 | 5,474
Other investments [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Other investments | 1,500 | 1,000
Significant Other Observable Inputs (Level 2) [Member] | Fixed Maturities [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Assets, securities valued using market approach | 6,463 | 56,674
Fair Value, Measurements, Recurring [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Fair Value Based on NAV Practical Expedient | 5,541 | 5,474
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Other investments, fair value | 7,041 | 13,060
Total | $ 3,891,628 | $ 3,984,726
Percentage of total assets | 56.90% | 63.70%
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Fixed Maturities [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Assets, valued by third party, percentage | 99.90% | 98.80%
Assets, valued using market approach, percentage | 0.10% | 1.20%
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | U.S. treasury bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | $ 5,336 | $ 5,413
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | U.S. agency bonds – mortgage-backed [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 2,006,402 | 1,716,038
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | U.S. agency bonds – other [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value |  | 18,102
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Non-U.S. government and supranational bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 31,596 | 29,934
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Asset-backed securities [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 262,261 | 220,876
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Corporate bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 1,576,389 | 1,916,205
Fair Value, Measurements, Recurring [Member] | Total Fair Value [Member] | Municipal bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 2,603 | 65,098
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Other investments, fair value | 0 | 6,586
Total | $ 5,336 | $ 11,999
Percentage of total assets | 0.10% | 0.20%
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. treasury bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | $ 5,336 | $ 5,413
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. agency bonds – mortgage-backed [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 0 | 0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. agency bonds – other [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value |  | 0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Non-U.S. government and supranational bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 0 | 0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Asset-backed securities [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 0 | 0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 0 | 0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 0 | 0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Other investments, fair value | 0 | 0
Total | $ 3,879,251 | $ 3,966,253
Percentage of total assets | 56.70% | 63.40%
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. treasury bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | $ 0 | $ 0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. agency bonds – mortgage-backed [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 2,006,402 | 1,716,038
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. agency bonds – other [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value |  | 18,102
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Non-U.S. government and supranational bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 31,596 | 29,934
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Asset-backed securities [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 262,261 | 220,876
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 1,576,389 | 1,916,205
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Municipal bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 2,603 | 65,098
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Other investments, fair value | 1,500 | 1,000
Total | $ 1,500 | $ 1,000
Percentage of total assets | 0.00% | 0.00%
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. treasury bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | $ 0 | $ 0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. agency bonds – mortgage-backed [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 0 | 0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. agency bonds – other [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value |  | 0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Non-U.S. government and supranational bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 0 | 0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Asset-backed securities [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 0 | 0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 0 | 0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Municipal bonds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
AFS fixed maturities, fair value | 0 | 0
Other investments [Member] | Fair Value, Measurements, Recurring [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Fair Value Based on NAV Practical Expedient | $ 5,541 | $ 5,474
Percentage of total assets | 0.10% | 0.10%

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