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v3.10.0.1

Investments (Details) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2018 USD ($) security | Sep. 30, 2017 USD ($) | Sep. 30, 2018 USD ($) security | Sep. 30, 2017 USD ($) | Dec. 31, 2017 USD ($) security
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized Cost | $ 5,042,011,000 |  | $ 5,042,011,000 |  | $ 4,946,278,000
Fair Value | 4,969,612,000 |  | 4,969,612,000 |  | 4,983,315,000
Other than Temporary Impairment Losses, Portion in Other Comprehensive Income |  |  | 0 |  | 0
Assets held by insurance regulators | 13,400,000 |  | 13,400,000 |  | $ 13,600,000
Proceeds from sales of fixed income securities |  |  | 338,900,000 | $ 233,200,000 |
Gross realized gains |  |  | 400,000 | 900,000 |
Gross realized losses |  |  | 3,300,000 | 1,100,000 |
Net impairment losses recognized in earnings | 500,000 | $ 0 | $ 1,800,000 | $ 0 |
Federal Home Loan Bank advances, collateral, value of principal, percent (as a percent) |  |  | 102.00% |  |
FHLB advance collateral | $ 166,100,000 |  | $ 166,100,000 |  |
Number of securities in unrealized loss position (in securities) | security | 810 |  | 810 |  | 586
Total fixed income securities |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized Cost | $ 5,042,011,000 |  | $ 5,042,011,000 |  | $ 4,946,278,000
Gross Unrealized Gains | 19,439,000 |  | 19,439,000 |  | 68,584,000
Gross Unrealized Losses | (91,838,000) |  | (91,838,000) |  | (31,547,000)
Fair Value | 4,969,612,000 |  | 4,969,612,000 |  | 4,983,315,000
U.S. Treasury securities and obligations of U.S. government corporations and agencies |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized Cost | 179,395,000 |  | 179,395,000 |  | 179,850,000
Gross Unrealized Gains | 174,000 |  | 174,000 |  | 274,000
Gross Unrealized Losses | (3,353,000) |  | (3,353,000) |  | (1,278,000)
Fair Value | 176,216,000 |  | 176,216,000 |  | 178,846,000
Obligations of U.S. states and political subdivisions |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized Cost | 1,738,417,000 |  | 1,738,417,000 |  | 2,105,063,000
Gross Unrealized Gains | 17,797,000 |  | 17,797,000 |  | 56,210,000
Gross Unrealized Losses | (21,608,000) |  | (21,608,000) |  | (8,749,000)
Fair Value | 1,734,606,000 |  | 1,734,606,000 |  | 2,152,524,000
Corporate debt securities |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized Cost | 2,296,218,000 |  | 2,296,218,000 |  | 2,065,475,000
Gross Unrealized Gains | 1,152,000 |  | 1,152,000 |  | 10,532,000
Gross Unrealized Losses | (42,305,000) |  | (42,305,000) |  | (9,169,000)
Fair Value | 2,255,065,000 |  | 2,255,065,000 |  | 2,066,838,000
Asset backed securities (“ABS”) |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized Cost | 71,481,000 |  | 71,481,000 |  | 4,925,000
Gross Unrealized Gains | 0 |  | 0 |  | 0
Gross Unrealized Losses | (546,000) |  | (546,000) |  | (2,000)
Fair Value | 70,935,000 |  | 70,935,000 |  | 4,923,000
Residential mortgage backed securities (“RMBS”) |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized Cost | 166,522,000 |  | 166,522,000 |  | 189,153,000
Gross Unrealized Gains | 35,000 |  | 35,000 |  | 60,000
Gross Unrealized Losses | (11,594,000) |  | (11,594,000) |  | (7,364,000)
Fair Value | 154,963,000 |  | 154,963,000 |  | 181,849,000
Commercial mortgage backed securities (“CMBS”) |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized Cost | 281,980,000 |  | 281,980,000 |  | 301,014,000
Gross Unrealized Gains | 214,000 |  | 214,000 |  | 1,204,000
Gross Unrealized Losses | (11,974,000) |  | (11,974,000) |  | (4,906,000)
Fair Value | 270,220,000 |  | 270,220,000 |  | 297,312,000
Collateralized loan obligations (“CLO”) |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Amortized Cost | 307,998,000 |  | 307,998,000 |  | 100,798,000
Gross Unrealized Gains | 67,000 |  | 67,000 |  | 304,000
Gross Unrealized Losses | (458,000) |  | (458,000) |  | (79,000)
Fair Value | $ 307,607,000 |  | $ 307,607,000 |  | $ 101,023,000

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