Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2025		Sep. 30, 2025		Jun. 30, 2025		Mar. 31, 2025		Dec. 31, 2024		Sep. 30, 2024		Jun. 30, 2024		Mar. 31, 2024		Dec. 31, 2025		Dec. 31, 2024		Dec. 31, 2023
Revenues
Net premiums earned (Note 8)																	$ 941,865		$ 939,237		$ 909,363
Net investment income (Note 7)																	248,764		264,814		252,093
Net gains (losses) on investments and other financial instruments (includes net realized gains (losses) on investments of $(3,890), $(7,821) and $(10,735)) (Note 7)																	(24)		(4,347)		9,405
Other income																	6,479		6,595		6,441
Total revenues	$ 300,512		$ 303,186		$ 298,551		$ 294,835		$ 292,669		$ 313,380		$ 298,580		$ 301,670		1,197,084		1,206,299		1,177,302
Expenses
Provision for losses																	66,768		(2,248)		(42,136)
Policy acquisition costs																	25,039		27,316		24,578
Other operating expenses																	245,759		247,618		244,793
Interest expense (Note 12)																	68,290		88,006		86,188
Total expenses																	405,856		360,692		313,423
Pretax income from continuing operations																	791,228		845,607		863,879
Income tax provision																	173,049		185,292		188,019
Net income from continuing operations	158,802		152,802		154,485		152,090		163,755		166,555		163,903		166,102		618,179		660,315		675,860
Income (loss) from discontinued operations, net of tax	(3,959)		(11,359)		(12,689)		(7,532)		(15,464)		(14,663)		(12,000)		(13,748)		(35,539)		(55,875)		(72,741)
Net income	$ 154,843		$ 141,443		$ 141,796		$ 144,558		$ 148,291		$ 151,892		$ 151,903		$ 152,354		$ 582,640		$ 604,440		$ 603,119
Net income per share
Net income from continuing operations, Basic	$ 1.16	[1]	$ 1.12	[1]	$ 1.12	[1]	$ 1.04	[1]	$ 1.09	[1]	$ 1.1	[1]	$ 1.07	[1]	$ 1.08	[1]	$ 4.43	[1]	$ 4.33	[1]	$ 4.27
Income (loss) from discontinued operations, net of tax, Basic	(0.03)	[1]	(0.08)	[1]	(0.09)	[1]	(0.05)	[1]	(0.1)	[1]	(0.1)	[1]	(0.08)	[1]	(0.09)	[1]	(0.25)	[1]	(0.37)	[1]	(0.46)
Basic net income per share	1.13	[1]	1.04	[1]	1.03	[1]	0.99	[1]	0.99	[1]	1	[1]	0.99	[1]	0.99	[1]	4.18	[1]	3.96	[1]	3.81
Net income from continuing operations, Diluted	1.15	[1]	1.11	[1]	1.11	[1]	1.03	[1]	1.08	[1]	1.09	[1]	1.06	[1]	1.07	[1]	4.39	[1]	4.28	[1]	4.22
Income (loss) from discontinued operations, net of tax, Diluted	(0.03)	[1]	(0.08)	[1]	(0.09)	[1]	(0.05)	[1]	(0.1)	[1]	(0.1)	[1]	(0.08)	[1]	(0.09)	[1]	(0.25)	[1]	(0.36)	[1]	(0.45)
Diluted net income per share	$ 1.12	[1]	$ 1.03	[1]	$ 1.02	[1]	$ 0.98	[1]	$ 0.98	[1]	$ 0.99	[1]	$ 0.98	[1]	$ 0.98	[1]	$ 4.14	[1]	$ 3.92	[1]	$ 3.77
Weighted average number of common shares outstanding-basic (in shares)	137,032	[1]	137,003	[1]	137,376	[1]	145,618	[1]	150,302	[1]	151,846	[1]	153,110	[1]	153,817	[1]	139,445	[1]	152,465	[1]	158,140
Weighted average number of common and common equivalent shares outstanding-diluted (in shares)	138,250	[1]	137,926	[1]	138,360	[1]	147,727	[1]	151,912	[1]	153,073	[1]	154,399	[1]	155,971	[1]	140,811	[1]	154,191	[1]	160,133

[1] Net income per share is computed independently for each period presented. Consequently, the sum of the quarters may not equal the total net income per share for the year. For all diluted net income per shares calculations, the determination of whether potential common shares are dilutive or anti-dilutive is based on net income.