Investments - Summarized Fair Value and Gross Unrealized Losses on Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014 Security	Dec. 31, 2013 Security
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	108	95
Less than 12 months, Fair value	$ 183,191	$ 227,241
Less than 12 months, Unrealized losses	(702)	(4,153)
12 months or longer, Number of issues	24
12 months or longer, Fair value	74,973
12 months or longer, Unrealized losses	(2,799)
U.S. Government Obligations and Agencies [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	3	6
Less than 12 months, Fair value	27,341	71,042
Less than 12 months, Unrealized losses	(55)	(1,033)
12 months or longer, Number of issues	4
12 months or longer, Fair value	34,050
12 months or longer, Unrealized losses	(572)
Corporate Bonds [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	67	55
Less than 12 months, Fair value	58,271	65,926
Less than 12 months, Unrealized losses	(238)	(770)
12 months or longer, Number of issues	12
12 months or longer, Fair value	15,105
12 months or longer, Unrealized losses	(126)
Mortgage-Backed and Asset-Backed Securities [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	20	16
Less than 12 months, Fair value	48,335	67,110
Less than 12 months, Unrealized losses	(273)	(577)
12 months or longer, Number of issues	5
12 months or longer, Fair value	16,842
12 months or longer, Unrealized losses	(229)
Redeemable Preferred Stock [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	12
Less than 12 months, Fair value	1,153
Less than 12 months, Unrealized losses	(9)
Common Stock [Member] \| Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	2	13
Less than 12 months, Fair value	87	3,517
Less than 12 months, Unrealized losses	(20)	(121)
12 months or longer, Number of issues	2
12 months or longer, Fair value	117
12 months or longer, Unrealized losses	(45)
Mutual Funds [Member] \| Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	2	5
Less than 12 months, Fair value	10,514	19,646
Less than 12 months, Unrealized losses	(97)	(1,652)
12 months or longer, Number of issues	1
12 months or longer, Fair value	8,859
12 months or longer, Unrealized losses	(1,827)
Short-term Investments [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	2
Less than 12 months, Fair value	37,490
Less than 12 months, Unrealized losses	$ (10)

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Paragraph 6

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.

+ References

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- Definition

This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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

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-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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Number of investment positions in available-for-sale investments that have been in a continuous unrealized loss position for greater than or equal to a year for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

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Number of investment positions in available-for-sale investments in a continuous unrealized loss position for less than one year or normal operating cycle, if longer, for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

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