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Investments (Net Investment Income) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Net investment income earned	$ 35,786,000	$ 32,986,000	$ 118,604,000	$ 104,237,000
Increase In Net Investment Income Before Tax	2,800,000		14,400,000
Fixed Maturity Securities [Member]
Net investment income earned	31,960,000	31,741,000	97,835,000	97,914,000
Equity Securities [Member]
Net investment income earned	1,197,000	347,000	2,299,000	1,279,000
Short-term Investments [Member]
Net investment income earned	28,000	134,000	123,000	367,000
Other Investments [Member]
Net investment income earned	4,494,000	2,400,000	24,082,000	11,216,000
Investment Expenses [Member]
Net investment income earned	$ (1,893,000)	$ (1,636,000)	$ (5,735,000)	$ (6,539,000)

X

- Definition

This item represents the increase (decrease) in income earned from investments in securities and other investments including dividends, interest, and returns on other investments in the current reporting period as compared to the comparable prior year period. This item does not include realized gains (losses).

+ Details

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X

- Definition

The income earned from investments in securities and other investments including dividends, interest, and returns on other investments. This item does not include realized gains (losses).

+ Details

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Data Type:	xbrli:monetaryItemType
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