Segment Information (Revenue From Continuing Operations by Segment) (Details) (USD $) In Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Total net premiums earned	$ 355,580	$ 352,190	$ 706,923	$ 708,392
Other income	2,499	2,247	5,379	4,515
Total Insurance Operations revenues	357,968	354,421	712,081	712,889
Net investment income	39,345	36,545	82,818	71,251
Net realized gain (loss) on investments	2,146	(3,264)	7,906	(3,328)
Total investment income, before federal income tax	41,491	33,281	90,724	67,923
Total all segments	399,459	387,702	802,805	780,812
Total revenues	399,570	387,718	803,026	780,830
Commercial Automobile [Member]
Total net premiums earned	69,198	73,176	138,868	147,492
Workers Compensation [Member]
Total net premiums earned	63,855	62,069	126,381	126,710
General Liability [Member]
Total net premiums earned	85,672	83,967	168,238	169,188
Commercial Property [Member]
Total net premiums earned	47,877	50,294	96,070	100,630
Business Owners Policy [Member]
Total net premiums earned	16,407	16,152	32,892	32,438
Bonds Segment [Member]
Total net premiums earned	4,725	4,828	9,492	9,431
Other Commercial [Member]
Total net premiums earned	2,561	2,515	5,117	5,020
Total Commercial Lines [Member]
Total net premiums earned	290,295	293,001	577,058	590,909
Personal Automobile [Member]
Total net premiums earned	37,189	35,243	74,151	69,563
Homeowners [Member]
Total net premiums earned	25,060	21,126	49,615	41,619
Other Personal [Member]
Total net premiums earned	3,036	2,820	6,099	6,301
Total Personal Lines [Member]
Total net premiums earned	65,285	59,189	129,865	117,483
Miscellaneous Income [Member]
Other income	2,388	2,231	5,158	4,497
Other Income [Member]
Other income	$ 111	$ 16	$ 221	$ 18

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).

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The income earned from investments in securities and other investments including dividends, interest, and returns on other investments, including realized gains/losses.

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Revenue from insurance services, including net premiums earned, gain on sale of insurance block, agency management fees and insurance contract fees and commissions.

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Reflects the sum of all other revenue and income recognized by the entity in the period not otherwise specified in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 4
-Article 7

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Premiums recognized as revenue in the period earned on all property and casualty insurance and reinsurance contracts after subtracting any amounts ceded to another insurer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 113
-Paragraph 27

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 1
-Article 7

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 18
-Article 12

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The net realized gains or losses on investments during the period.

+ References

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

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Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 1
-Article 5

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Total revenues for reportable segments.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 131
-Paragraph 32
-Subparagraph a

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