Consolidated Statements Of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Net premiums earned	$ 801,205	$ 790,850	$ 2,388,641	$ 2,337,256
Net investment income	30,988	30,371	94,058	91,440
Net realized investment gains (losses)	20,718	(15,465)	66,334	54,973
Other	5,446	2,406	9,675	6,416
Total revenues	858,357	808,162	2,558,708	2,490,085
Expenses:
Losses and loss adjustment expenses	595,290	576,316	1,790,550	1,765,484
Policy acquisition costs	136,290	140,203	416,728	421,685
Other operating expenses	64,339	59,006	182,959	178,000
Interest	4,191	1,012	10,873	2,922
Total expenses	800,110	776,537	2,401,110	2,368,091
Income before income taxes	58,247	31,625	157,598	121,994
Income tax expense	11,762	4,695	32,500	22,868
Net income	$ 46,485	$ 26,930	$ 125,098	$ 99,126
Net income per share:
Basic (in dollars per share)	$ 0.84	$ 0.49	$ 2.26	$ 1.79
Diluted (in dollars per share)	$ 0.84	$ 0.49	$ 2.26	$ 1.79
Weighted average shares outstanding:
Basic (in shares)	55,324	55,259	55,311	55,238
Diluted (in shares)	55,334	55,328	55,323	55,304
Dividends paid per share (in dollars per share)	$ 0.6225	$ 0.6200	$ 1.8675	$ 1.8600