Investments - Additional Information (Detail) $ in Thousands	6 Months Ended
Jun. 30, 2018 USD ($) Securities	Dec. 31, 2017 USD ($) Securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	$ 23,167	$ 30,848
Number of securities in unrealized loss position \| Securities	26	27
Proceeds from sale of investment in fixed maturity securities	$ 15,800
Proceeds from Sale of Other Investments	$ 16,300
Investment security maturity date, start	Jan. 01, 2018
Investment security maturity date, End	Jun. 30, 2018
Gross realized gains and losses of securities	insignificant
Investments on deposit with the state insurance department	$ 4,000
U.S. Treasury securities, obligations of U.S. Government agencies and Municipalities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	$ 22,345	$ 29,764

The latest maturity date when short-term debt instruments are reported on the Schedule of Investments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
-Footnote 2

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The earliest maturity date when short-term debt instruments are reported on the Schedule of Investments.

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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
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Carrying amount of cash and investment securities on deposit with state regulatory authorities in connection with capital requirements.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 320
-Section 50
-Paragraph 1
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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
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-Paragraph 1
-Subparagraph (b)
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Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

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The cash inflow associated with the sale or maturity (principal being due) of securities not classified as either held-to-maturity securities or trading securities which are classified as available-for-sale securities.

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Amount of cash inflow from the sale of investments classified as other.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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