Investments - Summary of the Amortized Cost and Fair Value of Investments in Fixed Maturity Securities, Classified as Available-for-sale (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Investment [Line Items]
Less than one year, Amortized Cost	$ 41,459
One to five years, Amortized Cost	60,956
Five to ten years, Amortized Cost	15,939
More than ten years, Amortized Cost	141,770
Total, Amortized Cost	270,135	244,409
Less than one year, Fair Value	41,542
One to five years, Fair Value	61,229
Five to ten years, Fair Value	16,289
More than ten years, Fair Value	142,109
Total, Fair Value	268,189	237,877
U.S. agency-based mortgage-backed securities [Member]
Investment [Line Items]
Available for sale securities, Amortized Cost	10,011
Available for sale securities, Fair Value	$ 7,020

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Amount of available-for-sale debt securities at cost, net of adjustments, which include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the next rolling twelve months following the latest balance sheet presented. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

+ References

No definition available.

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Amount of available-for-sale debt securities at fair value maturing in the next rolling twelve months following the latest balance sheet presented.

+ References

No definition available.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing after the tenth rolling twelve months following the latest balance sheet presented. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

+ References

No definition available.

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Amount of available-for-sale debt securities at fair value maturing after the tenth rolling twelve months following the latest balance sheet presented.

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No definition available.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the sixth rolling twelve months through the tenth rolling twelve months following the latest balance sheet presented. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

+ References

No definition available.

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Amount of available-for-sale debt securities at fair value maturing in the sixth rolling twelve months through the tenth rolling twelve months following the latest balance sheet presented.

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No definition available.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the second rolling twelve months through the fifth rolling twelve months following the latest balance sheet presented. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

+ References

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Amount of available-for-sale debt securities at fair value maturing in the second rolling twelve months through the fifth rolling twelve months following the latest balance sheet presented.

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No definition available.

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Amount of available-for-sale debt securities at cost, net of adjustments, that do not have a single maturity date and which the entity has decided to disclose separately rather than allocating the cost over several maturity groupings. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

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Amount of available-for-sale debt securities at fair value that do not have a single maturity date and which the entity has decided to disclose separately rather than allocating the fair value over several maturity groupings.

+ References

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-Publisher FASB

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

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