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Investments - Additional Information (Detail) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 USD ($) Security | Jun. 30, 2017 USD ($) | Jun. 30, 2018 USD ($) Security | Jun. 30, 2017 USD ($)
Investments Schedule [Abstract] |  |  |  |
Individual fixed maturity held in unrealized loss position | Security | 419 |  | 419 |
Individual fixed maturity held in unrealized loss position longer than 12 months | Security | 46 |  | 46 |
Impairment losses recognized | $ |  |  | $ 0 | $ 0
Net realized losses on investments | $ | $ (1,111,000) | $ (388,000) | $ (1,142,000) | $ (569,000)

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- Definition Number of individual fixed maturity securities in unrealized loss position. + References No definition available. + Details
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- Definition Number of individual investment securities in unrealized loss position greater than twelve months. + References No definition available. + Details
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- References No definition available. + Details
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- Definition The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 8A -URI http://asc.fasb.org/extlink&oid=109979856&loc=SL6284422-111562 + Details
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- Definition Amount of realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI). + References No definition available. + Details
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