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Fair Value of Financial Instruments - Narrative (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Percentage of investment portfolio fair value pricing services or index price | 92.30% | 90.70% |
Net investment gains (losses) | $ 7,931 | $ (13,410) | $ (5,076)
Level 3 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Percentage of investment portfolio fair value pricing services or index price | 3.00% |  |
Realized loss on impairment of securities | $ 484 | 1,833 |
Net investment gains (losses) | $ (7,518) | $ 12,942 |

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- Definition Amount of loss realized on the sale of debt or equity securities classified as available-for-sale. Excludes other than temporary impairments (OTTI). + References No definition available. + Details
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- Definition Net Increase or Decrease in the fair value of the embedded derivative or group of embedded derivatives included in earnings in the period. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 15 -URI http://asc.fasb.org/subtopic&trid=2229187 + Details
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