Realized Gains and Losses Excluding Net Other-Than-Temporary Impairment Losses Recognized in Earnings (Detail) (USD $) In Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Gain (Loss) on Investments [Line Items]
Net realized gains (losses)	$ 3,238	$ 4,521	$ 4,856	$ 21,653
Fixed maturities
Gain (Loss) on Investments [Line Items]
Gains	3,315	4,790	10,625	22,440
Losses	(77)	(1,036)	(6,610)	(1,319)
Net realized gains (losses)	3,238	3,754	4,015	21,121
Equity Securities
Gain (Loss) on Investments [Line Items]
Gains		773	841	773
Losses		(6)		(241)
Net realized gains (losses)		$ 767	$ 841	$ 532

The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 3

-Subparagraph a

-Article 7

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.3(a))

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 325

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6485959&loc=d3e22529-158502

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration