Condensed Consolidated Statements of Income - Unaudited - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues:
Direct premiums	$ 736,606	$ 692,258	$ 2,156,331	$ 2,056,806
Ceded premiums	(393,716)	(388,982)	(1,183,090)	(1,179,364)
Net premiums	342,890	303,276	973,241	877,442
Commissions and fees	185,302	179,719	547,159	525,502
Investment income net of investment expenses	37,657	35,444	103,333	106,867
Interest expense on surplus note	(14,704)	(12,769)	(42,250)	(35,212)
Net investment income	22,953	22,675	61,083	71,655
Realized investment gains (losses)	642	285	(7,645)	4,200
Other, net	16,674	14,698	45,375	41,746
Revenues	568,461	520,653	1,619,213	1,520,545
Benefits and expenses:
Benefits and claims	160,166	128,684	434,625	366,036
Amortization of deferred policy acquisition costs	47,491	63,883	170,979	187,273
Sales commissions	91,950	89,061	274,049	262,960
Insurance expenses	46,109	44,854	138,572	132,825
Insurance commissions	9,694	6,980	22,871	18,427
Interest expense	7,221	7,209	21,614	21,589
Other operating expenses	59,347	54,843	181,413	176,468
Total benefits and expenses	421,978	395,514	1,244,123	1,165,578
Income before income taxes	146,483	125,139	375,090	354,967
Income taxes	34,382	28,916	89,010	82,133
Net income	$ 112,101	$ 96,223	$ 286,080	$ 272,834
Earnings per share:
Basic earnings per share	$ 2.82	$ 2.28	$ 7.07	$ 6.40
Diluted earnings per share	$ 2.81	$ 2.28	$ 7.05	$ 6.38
Weighted-average shares used in computing earnings per share:
Basic	39,588	41,964	40,281	42,420
Diluted	39,710	42,100	40,396	42,550
Supplemental disclosures:
Total impairment losses	$ (23)	$ (1,064)	$ (4,269)	$ (1,225)
Net impairment losses recognized in earnings	(23)	(1,064)	(4,269)	(1,225)
Other net realized investment gains (losses)	92	536	1,176	733
Net gains (losses) recognized on equity securities	573	813	(4,552)	4,692
Net realized investment gains (losses)	$ 642	$ 285	$ (7,645)	$ 4,200