Consolidated Statements of Cash Flows - USD ($) $ in Thousands		12 Months Ended
	Feb. 09, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net income		$ 742,934	$ 600,671	$ 393,626
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Net (gains) losses on investments and other financial instruments		80,733	(15,603)	(60,277)
Purchases of mortgage loans held for sale		(3,890)	0	0
Proceeds from repayments of mortgage loans held for sale		393	0	0
Amortization of other acquired intangible assets		4,308	3,450	5,144
Depreciation, other amortization, and other impairments, net		72,267	72,020	66,585
Deferred income tax provision		206,925	161,793	102,079
Change in:
Accrued investment income		(7,281)	1,235	(1,714)
Accounts and notes receivable		4,210	(2,722)	(29,280)
Reinsurance recoverable		42,263	5,306	(56,226)
Deferred policy acquisition costs		(2,143)	1,988	2,454
Prepaid federal income tax		(242,245)	(143,234)	(76,089)
Other assets		65,744	65,071	114,769
Unearned premiums		(57,611)	(119,701)	(178,031)
Reserve for losses and LAE		(401,799)	(19,771)	443,648
Reinsurance funds withheld		(76,011)	(50,477)	(13,274)
Other liabilities		(40,499)	(2,914)	(54,980)
Net cash provided by (used in) operating activities		388,298	557,112	658,434
Proceeds from sales of:
Fixed-maturities available for sale		399,371	735,340	963,589
Trading securities		8,868	7,952	11,602
Equity securities		8,004	36,748	90,450
Proceeds from redemptions of:
Fixed-maturities available for sale		789,929	1,225,626	645,068
Trading securities		102,121	16,668	22,913
Purchases of:
Fixed-maturities available for sale		(1,414,966)	(1,980,155)	(2,449,762)
Equity securities		(24,637)	(105,649)	(85,014)
Sales, redemptions and (purchases) of:
Short-term investments, net		150,694	68,083	(82,925)
Other assets and other invested assets, net		(6,887)	6,126	1,434
Proceeds from sale of subsidiary, net of cash sold		0	0	16,481
Additions to property and equipment		(17,672)	(12,601)	(17,016)
Net cash provided by (used in) investing activities		(5,175)	(1,862)	(883,180)
Cash flows from financing activities
Dividends and dividend equivalents paid		(135,437)	(103,298)	(97,458)
Issuance of common stock		1,341	1,382	1,553
Repurchases of common stock	$ (400,000)	(400,195)	(399,100)	(226,305)
Issuance of senior notes, net		0	0	515,567
Credit facility commitment fees paid		(814)	(3,325)	(2,292)
Change in secured borrowings, net (with terms three months or less)		102,983	13,565	(37,475)
Proceeds from secured borrowings (with terms greater than three months)		28,704	42,000	207,034
Repayments of secured borrowings (with terms greater than three months)		(75,765)	(48,000)	(138,006)
Net cash provided by (used in) financing activities		(479,183)	(496,776)	222,618
Increase (decrease) in cash and restricted cash		(96,060)	58,474	(2,128)
Cash and restricted cash, beginning of period		152,620	94,146	96,274
Cash and restricted cash, end of period		56,560	152,620	94,146
Supplemental disclosures of cash flow information
Income taxes paid (Note 10)		243,500	143,973	81,404
Interest paid		$ 79,062	$ 78,704	$ 60,564