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Fair Value Measurements - Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Total realized/unrealized gains (losses) [Abstract] |  |  |
State premium tax credit investments, average maturity | 3 years |  |
Annual average discount rate (in hundredths) | 7.10% |  |
Total Investments [Member] |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Balance at beginning of period | $ 4,083 | $ 2,167 | $ 2,744
Total realized/unrealized gains (losses) [Abstract] |  |  |
Included in earnings and reported as net realized investment gains | 3,579 |  |
Included in earnings and reported as losses incurred, net | 0 | 0 | 0
Purchases | 4,258 | 2,541 | 30
Sales | (6,961) | (625) | (607)
Balance at end of period | 4,959 | 4,083 | 2,167
Obligations of U.S. states and political subdivisions |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Balance at beginning of period | 1,228 | 1,846 | 2,423
Total realized/unrealized gains (losses) [Abstract] |  |  |
Included in earnings and reported as net realized investment gains | 0 |  |
Included in earnings and reported as losses incurred, net | 0 | 0 | 0
Purchases | 0 | 7 | 30
Sales | (537) | (625) | (607)
Balance at end of period | 691 | 1,228 | 1,846
Equity securities |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Balance at beginning of period | 2,855 | 321 | 321
Total realized/unrealized gains (losses) [Abstract] |  |  |
Included in earnings and reported as net realized investment gains | 3,579 |  |
Included in earnings and reported as losses incurred, net | 0 | 0 | 0
Purchases | 4,258 | 2,534 | 0
Sales | (6,424) | 0 | 0
Balance at end of period | 4,268 | 2,855 | 321
Real Estate Acquired |  |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |  |
Balance at beginning of period | 12,149 | 12,658 | 13,280
Total realized/unrealized gains (losses) [Abstract] |  |  |
Included in earnings and reported as net realized investment gains | 0 |  |
Included in earnings and reported as losses incurred, net | (1,142) | (2,322) | (4,129)
Purchases | 36,859 | 34,624 | 42,247
Sales | (36,118) | (32,811) | (38,740)
Balance at end of period | $ 11,748 | $ 12,149 | $ 12,658

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- Definition This element represents annual average discount rate used for fair value of state premium tax credit investments. + References No definition available. + Details
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- Definition Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included In Earnings, Reported As Net Realized Investment Gain, Net + References No definition available. + Details
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- Definition This element represents state premium tax credit investments, average maturity. + References No definition available. + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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