Investments - Summarized Fair Value and Gross Unrealized Losses on Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015 Security	Dec. 31, 2014 Security
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	35	108
Less than 12 months, Fair value	$ 64,765	$ 183,191
Less than 12 months, Unrealized losses	(416)	(702)
12 months or longer, Number of issues	13	24
12 months or longer, Fair value	31,178	74,973
12 months or longer, Unrealized losses	(2,321)	(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	3
Less than 12 months, Fair value	24,001	27,341
Less than 12 months, Unrealized losses	(33)	(55)
12 months or longer, Number of issues	2	4
12 months or longer, Fair value	3,507	34,050
12 months or longer, Unrealized losses	(143)	(572)
Corporate Bonds [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	13	67
Less than 12 months, Fair value	14,351	58,271
Less than 12 months, Unrealized losses	(97)	(238)
12 months or longer, Number of issues	3	12
12 months or longer, Fair value	3,397	15,105
12 months or longer, Unrealized losses	(17)	(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	10	20
Less than 12 months, Fair value	23,408	48,335
Less than 12 months, Unrealized losses	(63)	(273)
12 months or longer, Number of issues	5	5
12 months or longer, Fair value	15,395	16,842
12 months or longer, Unrealized losses	(216)	(229)
Redeemable Preferred Stock [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	5	12
Less than 12 months, Fair value	569	1,153
Less than 12 months, Unrealized losses	(1)	(9)
Common Stock [Member] \| Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	3	2
Less than 12 months, Fair value	1,911	87
Less than 12 months, Unrealized losses	(166)	(20)
12 months or longer, Number of issues	2	2
12 months or longer, Fair value	78	117
12 months or longer, Unrealized losses	(60)	(45)
Mutual Funds [Member] \| Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Less than 12 months, Number of issues	1	2
Less than 12 months, Fair value	525	10,514
Less than 12 months, Unrealized losses	(56)	(97)
12 months or longer, Number of issues	1	1
12 months or longer, Fair value	8,801	8,859
12 months or longer, Unrealized losses	(1,885)	(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

-Topic 320

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-Section 50

-Paragraph 6

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

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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

-SubTopic 10

-Section 50

-Paragraph 7

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

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

-Publisher FASB

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-SubTopic 10

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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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