OPERATING SEGMENT INFORMATION (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
REVENUES
Segment totals before income taxes	$ 177,747	$ 163,702	$ 507,483	$ 462,406
Net investment income	14,200	13,598	41,764	39,331
Net realized gains	5,708	10,999	22,640	18,425
Consolidated revenue	197,655	188,299	571,887	520,162
NET EARNINGS (LOSSES)
Net underwriting income	30,428	31,818	79,529	77,175
Net investment income	14,200	13,598	41,764	39,331
Net realized gains	5,708	10,999	22,640	18,425
General corporate expense and interest on debt	(4,657)	(3,670)	(13,129)	(10,773)
Equity in earnings of unconsolidated investee	2,915	2,564	12,204	10,696
Earnings before income taxes	48,594	55,309	143,008	134,854
Income tax expense	15,340	17,662	45,060	42,458
Net earnings	33,254	37,647	97,948	92,396
Casualty segment
REVENUES
Segment totals before income taxes	96,181	83,966	281,518	235,307
NET EARNINGS (LOSSES)
Net underwriting income	13,786	20,799	36,331	39,517
Property segment
REVENUES
Segment totals before income taxes	54,143	52,705	146,252	147,305
NET EARNINGS (LOSSES)
Net underwriting income	7,498	6,468	19,469	19,614
Surety segment
REVENUES
Segment totals before income taxes	27,423	27,031	79,713	79,794
NET EARNINGS (LOSSES)
Net underwriting income	$ 9,144	$ 4,551	$ 23,729	$ 18,044