Investments - Summarized Fair Value and Gross Unrealized Losses on Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013 Security
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Number of issues	140
Less than 12 months, Fair value	$ 303,245
Less than 12 months, Unrealized losses	(4,494)
12 months or longer, Number of issues
12 months or longer, Fair value
12 months or longer, Unrealized losses
US Government and Agency Obligations [Member] \| Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Number of issues	9
Less than 12 months, Fair value	104,118
Less than 12 months, Unrealized losses	(1,081)
12 months or longer, Number of issues
12 months or longer, Fair value
12 months or longer, Unrealized losses
Corporate Bonds [Member] \| Fixed Maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Number of issues	77
Less than 12 months, Fair value	92,771
Less than 12 months, Unrealized losses	(1,467)
12 months or longer, Number of issues
12 months or longer, Fair value
12 months or longer, Unrealized losses
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	14
Less than 12 months, Fair value	61,831
Less than 12 months, Unrealized losses	(321)
12 months or longer, Number of issues
12 months or longer, Fair value
12 months or longer, Unrealized losses
Common Stock [Member] \| Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Number of issues	33
Less than 12 months, Fair value	8,314
Less than 12 months, Unrealized losses	(475)
12 months or longer, Number of issues
12 months or longer, Fair value
12 months or longer, Unrealized losses
Mutual Funds [Member] \| Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Number of issues	7
Less than 12 months, Fair value	36,211
Less than 12 months, Unrealized losses	(1,150)
12 months or longer, Number of issues
12 months or longer, Fair value
12 months or longer, Unrealized losses

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.

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

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (a)(1)

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

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Amount of accumulated pre-tax unrealized loss on investments in available-for-sale securities that have been in a loss position for twelve months or longer impacting investments.

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Amount of accumulated pre-tax unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months impacting investments.

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