Fair Value Measurements - Available-for-Sale Securities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financial Assets:
Restricted cash	$ 700	$ 700
Short-term Investments	508	66,479
Total fixed-maturity securities	209,914	182,723
Equity securities	29,861	41,143
Fair Value, Measurements, Recurring [Member]
Financial Assets:
Cash and cash equivalents	217,153	239,458
Restricted cash	700	700
Short-term Investments	508	66,479
Total available-for-sale securities	209,914	182,723
Equity securities	29,861	41,143
Fair Value, Measurements, Recurring [Member] \| U.S. Treasury and U.S. Government Agencies [Member]
Financial Assets:
Total fixed-maturity securities	26,652	61,797
Fair Value, Measurements, Recurring [Member] \| Corporate Bonds [Member]
Financial Assets:
Total fixed-maturity securities	164,273	101,905
Fair Value, Measurements, Recurring [Member] \| State, Municipalities, and Political Subdivisions [Member]
Financial Assets:
Total fixed-maturity securities	10,200	10,662
Fair Value, Measurements, Recurring [Member] \| Exchange-Traded Debt [Member]
Financial Assets:
Total fixed-maturity securities	8,667	8,247
Fair Value, Measurements, Recurring [Member] \| Redeemable Preferred Stock [Member]
Financial Assets:
Total fixed-maturity securities	122	112
Fair Value, Measurements, Recurring [Member] \| (Level 1) [Member]
Financial Assets:
Cash and cash equivalents	217,153	239,458
Restricted cash	700	700
Short-term Investments	508	66,479
Total available-for-sale securities	198,213	170,561
Equity securities	29,861	41,143
Fair Value, Measurements, Recurring [Member] \| (Level 1) [Member] \| U.S. Treasury and U.S. Government Agencies [Member]
Financial Assets:
Total fixed-maturity securities	25,151	60,297
Fair Value, Measurements, Recurring [Member] \| (Level 1) [Member] \| Corporate Bonds [Member]
Financial Assets:
Total fixed-maturity securities	164,273	101,905
Fair Value, Measurements, Recurring [Member] \| (Level 1) [Member] \| Exchange-Traded Debt [Member]
Financial Assets:
Total fixed-maturity securities	8,667	8,247
Fair Value, Measurements, Recurring [Member] \| (Level 1) [Member] \| Redeemable Preferred Stock [Member]
Financial Assets:
Total fixed-maturity securities	122	112
Fair Value, Measurements, Recurring [Member] \| (Level 2) [Member]
Financial Assets:
Total available-for-sale securities	11,701	12,162
Fair Value, Measurements, Recurring [Member] \| (Level 2) [Member] \| U.S. Treasury and U.S. Government Agencies [Member]
Financial Assets:
Total fixed-maturity securities	1,501	1,500
Fair Value, Measurements, Recurring [Member] \| (Level 2) [Member] \| State, Municipalities, and Political Subdivisions [Member]
Financial Assets:
Total fixed-maturity securities	10,200	10,662
Fair Value, Measurements, Recurring [Member] \| (Level 3) [Member]
Financial Assets:
Total available-for-sale securities

Disclosure fair value of financial assets.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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