OPERATING SEGMENT INFORMATION (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
REVENUE
Net premiums earned	$ 146,552	$ 128,334	$ 393,429	$ 366,356
Net investment income	15,954	16,762	47,437	50,127
Net realized gains (losses)	(177)	4,527	14,345	15,281
Consolidated revenue	162,329	149,623	455,211	431,764
NET EARNINGS
Net underwriting income	24,736	21,726	89,533	65,242
Net investment income	15,954	16,762	47,437	50,127
Net realized gains (losses)	(177)	4,527	14,345	15,281
General corporate expense and interest on debt	(3,107)	(3,660)	(10,100)	(9,943)
Equity in earnings of unconsolidated investee	713	1,648	7,215	7,327
Earnings before income taxes	38,119	41,003	148,430	128,034
Income tax expense	12,062	13,038	48,531	40,854
Net earnings	26,057	27,965	99,899	87,180
Casualty
REVENUE
Net premiums earned	60,626	57,684	173,937	175,690
NET EARNINGS
Net underwriting income	23,794	8,977	55,388	23,185
Property
REVENUE
Net premiums earned	59,226	50,167	148,015	132,133
NET EARNINGS
Net underwriting income	(1,926)	5,288	16,622	22,669
Surety
REVENUE
Net premiums earned	26,700	20,483	71,477	58,533
NET EARNINGS
Net underwriting income	$ 2,868	$ 7,461	$ 17,523	$ 19,388