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Investments - Gross Unrealized Gains and Losses and Cost or Amortized Cost and Fair Value of Investments Classified as Available-for-sale (Detail) (USD $) In Thousands, unless otherwise specified | Jun. 30, 2014 | Dec. 31, 2013
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Investment [Line Items] |  |
Cost or Amortized Cost | $ 295,686 | $ 263,891
Gross Unrealized Gains | 8,052 | 2,914
Gross Unrealized Losses | (4,053) | (9,035)
Fair Value | 299,685 | 257,770
Total fixed maturity [Member] |  |
Investment [Line Items] |  |
Cost or Amortized Cost | 282,240 | 244,409
Gross Unrealized Gains | 6,420 | 1,936
Gross Unrealized Losses | (4,047) | (8,468)
Fair Value | 284,613 | 237,877
Other investments [Member] |  |
Investment [Line Items] |  |
Cost or Amortized Cost | 10,000 | 10,000
Gross Unrealized Gains | 1,092 | 591
Fair Value | 11,092 | 10,591
States and political subdivisions [Member] |  |
Investment [Line Items] |  |
Cost or Amortized Cost | 151,140 | 154,024
Gross Unrealized Gains | 5,711 | 1,491
Gross Unrealized Losses | (1,759) | (5,140)
Fair Value | 155,092 | 150,375
Corporate bonds [Member] |  |
Investment [Line Items] |  |
Cost or Amortized Cost | 121,088 | 80,344
Gross Unrealized Gains | 708 | 445
Gross Unrealized Losses | (33) | (361)
Fair Value | 121,763 | 80,428
U.S. agency-based mortgage-backed securities [Member] |  |
Investment [Line Items] |  |
Cost or Amortized Cost | 10,012 | 10,041
Gross Unrealized Gains | 1 |
Gross Unrealized Losses | (2,255) | (2,967)
Fair Value | 7,758 | 7,074
Equity securities [Member] |  |
Investment [Line Items] |  |
Cost or Amortized Cost | 3,446 | 9,482
Gross Unrealized Gains | 540 | 387
Gross Unrealized Losses | (6) | (567)
Fair Value | $ 3,980 | $ 9,302

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- Definition Amount of accumulated pre-tax unrealized gain before deducting pre-tax unrealized losses on investments in available-for-sale securities impacting investments. + References No definition available. + Details
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- Definition Amount of accumulated pre-tax unrealized loss before deducting pre-tax unrealized gain on investments in available-for-sale securities impacting investments. + References No definition available. + Details
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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562 + Details
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- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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