Condensed Consolidated Statements of Earnings and Comprehensive Earnings (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net premiums earned	$ 149,943	$ 146,552	$ 428,807	$ 393,429
Net investment income	14,221	15,954	44,340	47,437
Net realized investment gains	5,481	80	17,389	14,602
Other-than-temporary impairment (OTTI) losses on investments		(257)	(1,156)	(257)
Consolidated revenue	169,645	162,329	489,380	455,211
Losses and settlement expenses	70,598	64,802	193,486	142,036
Policy acquisition costs	49,262	49,924	145,632	134,785
Insurance operating expenses	11,553	10,302	34,595	32,047
Interest expense on debt	1,512	1,513	4,537	4,537
General corporate expenses	2,099	1,594	5,901	5,563
Total expenses	135,024	128,135	384,151	318,968
Equity in earnings of unconsolidated investee	1,859	713	8,928	7,215
Earnings before income taxes	36,480	34,907	114,157	143,458
Income tax expense	11,017	10,938	35,908	46,791
Net earnings	25,463	23,969	78,249	96,667
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during the period	25,127	(14,518)	50,066	2,860
Less: Reclassification adjustment for (gains) losses included in net earnings	(4,080)	187	(12,353)	(9,183)
Other comprehensive earnings (loss)	21,047	(14,331)	37,713	(6,323)
Comprehensive earnings	$ 46,510	$ 9,638	$ 115,962	$ 90,344
Basic:
Basic net earnings per share (in dollars per share)	$ 1.20	$ 1.14	$ 3.69	$ 4.59
Basic comprehensive earnings per share (in dollars per share)	$ 2.19	$ 0.46	$ 5.47	$ 4.29
Diluted:
Diluted net earnings per share (in dollars per share)	$ 1.19	$ 1.12	$ 3.64	$ 4.53
Diluted comprehensive earnings per share (in dollars per share)	$ 2.16	$ 0.45	$ 5.39	$ 4.24
Weighted average number of common shares outstanding
Basic (in shares)	21,218	21,089	21,207	21,063
Diluted (in shares)	21,486	21,335	21,519	21,324
Cash dividends declared per common share (in dollars per share)	$ 0.32	$ 0.30	$ 0.94	$ 0.89