Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Net premiums earned	$ 858,135	$ 801,205	$ 2,500,178	$ 2,388,641
Net investment income	38,159	30,988	104,455	94,058
Net realized investment (losses) gains	(3,910)	20,718	(48,355)	66,334
Other	2,427	5,446	7,108	9,675
Total revenues	894,811	858,357	2,563,386	2,558,708
Expenses:
Losses and loss adjustment expenses	614,069	595,290	1,851,850	1,790,550
Policy acquisition costs	142,295	136,290	424,799	416,728
Other operating expenses	63,904	64,339	190,125	182,959
Interest	4,257	4,191	12,779	10,873
Total expenses	824,525	800,110	2,479,553	2,401,110
Income before income taxes	70,286	58,247	83,833	157,598
Income tax expense	11,708	11,762	7,682	32,500
Net income	$ 58,578	$ 46,485	$ 76,151	$ 125,098
Net income per share:
Basic (in dollars per share)	$ 1.06	$ 0.84	$ 1.38	$ 2.26
Diluted (in dollars per share)	$ 1.06	$ 0.84	$ 1.38	$ 2.26
Weighted average shares outstanding:
Basic (in shares)	55,337	55,324	55,334	55,311
Diluted (in shares)	55,341	55,334	55,337	55,323
Dividends paid per share (in dollars per share)	$ 0.6250	$ 0.6225	$ 1.875	$ 1.8675