Investments - Additional Information (Detail) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($) Securities	Dec. 31, 2016 USD ($) Securities
Schedule of Available-for-sale Securities [Line Items]
Short-term Investments	$ 24,965	$ 15,048
Number of securities in unrealized loss position \| Securities	27	20
Proceeds from sale of investment in fixed maturity securities	$ 5,800	$ 6,000
Money Market Funds, at Carrying Value		$ 9,100
Investments on deposit with the state insurance department	4,100
Time Deposits	$ 8,100

Carrying amount of cash and investment securities on deposit with state regulatory authorities in connection with capital requirements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 320
-Section 50
-Paragraph 1
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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.

+ References

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Investment in short-term money-market instruments (such as commercial paper, banker's acceptances, repurchase agreements, government securities, certificates of deposit, and so forth) which are highly liquid (that is, readily convertible to known amounts of cash) and so near their maturity that they present an insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify as cash equivalents by definition. Original maturity means an original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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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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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Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

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Amount of time deposit liabilities, including certificates of deposit.

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