Fair Value Measurements - Summary of Carrying Values and Corresponding Fair Values for Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities-held-to-maturity	$ 711,264	$ 664,371
Fixed maturity securities-held-to-maturity	686,618us-gaap_HeldToMaturitySecurities	639,631us-gaap_HeldToMaturitySecurities
Fixed maturity securities-available-for-sale	362,804	331,242
Equity securities	28	28
Short-term investments	12,184us-gaap_ShortTermInvestments	33,684us-gaap_ShortTermInvestments
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities-held-to-maturity	686,618	639,631
Fixed maturity securities-available-for-sale	362,804	331,242
Equity securities	28	28
Cash and cash equivalents	79,731	90,956
Short-term investments	12,184	33,684
Other investments	11,729	11,748
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed maturity securities-held-to-maturity	711,264	664,371
Fixed maturity securities-available-for-sale	362,804	331,242
Equity securities	28	28
Cash and cash equivalents	79,731	90,956
Short-term investments	12,184	33,684
Other investments	$ 11,729	$ 11,748

Amount of debt securities categorized neither as held-to-maturity nor trading.

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Amount of equity securities categorized neither as held-to-maturity nor as trading.

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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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-Glossary Cash

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-Glossary Cash Equivalents

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Fair value of investments in debt securities classified as held-to-maturity.

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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Investments which are intended to be sold in the short term (usually less than one year or the normal operating cycle, whichever is longer) including trading securities, available-for-sale securities, held-to-maturity securities, and other short-term investments not otherwise listed in the existing taxonomy.

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