Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net income	$ 603,119	$ 742,934	$ 600,671
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Net (gains) losses on investments and other financial instruments	(10,241)	80,733	(15,603)
Purchases of mortgage loans held for sale	(220,885)	(3,890)	0
Proceeds from sales of mortgage loans held for sale	172,573	0	0
Proceeds from repayments of mortgage loans held for sale	17,064	393	0
Impairment of goodwill	9,802	0	0
Amortization of other acquired intangible assets	5,483	4,308	3,450
Depreciation, other amortization, and other impairments, net	73,632	72,267	72,020
Deferred income tax provision	165,001	206,925	161,793
Change in:
Accrued investment income	(5,690)	(7,281)	1,235
Accounts and notes receivable	(1,618)	4,210	(2,722)
Reinsurance recoverable	(276)	42,263	5,306
Deferred policy acquisition costs	(258)	(2,143)	1,988
Prepaid federal income tax	(153,952)	(242,245)	(143,234)
Other assets	37,960	65,744	65,071
Unearned premiums	(46,083)	(57,611)	(119,701)
Reserve for losses and LAE	(56,695)	(401,799)	(19,771)
Reinsurance funds withheld	(21,503)	(76,011)	(50,477)
Other liabilities	(37,999)	(40,499)	(2,914)
Net cash provided by (used in) operating activities	529,434	388,298	557,112
Proceeds from sales of:
Fixed-maturities available for sale	331,880	399,371	735,340
Trading securities	9,123	8,868	7,952
Equity securities	67,953	8,004	36,748
Proceeds from redemptions of:
Fixed-maturities available for sale	498,081	789,929	1,225,626
Trading securities	1,707	102,121	16,668
Purchases of:
Fixed-maturities available for sale	(933,264)	(1,414,966)	(1,980,155)
Equity securities	(8,334)	(24,637)	(105,649)
Sales, redemptions and (purchases) of:
Short-term investments, net	(251,662)	150,694	68,083
Other assets and other invested assets, net	(45)	(6,887)	6,126
Additions to property and equipment	(16,281)	(17,672)	(12,601)
Net cash provided by (used in) investing activities	(300,842)	(5,175)	(1,862)
Cash flows from financing activities
Dividends and dividend equivalents paid	(145,908)	(135,437)	(103,298)
Issuance of common stock	1,755	1,341	1,382
Repurchases of common stock	(133,314)	(400,195)	(399,100)
Credit facility commitment fees paid	(904)	(814)	(3,325)
Change in secured borrowings, net (with terms three months or less)	38,229	102,983	13,565
Proceeds from secured borrowings (with terms greater than three months)	207,518	28,704	42,000
Repayments of secured borrowings (with terms greater than three months)	(232,463)	(75,765)	(48,000)
Net cash provided by (used in) financing activities	(265,087)	(479,183)	(496,776)
Increase (decrease) in cash and restricted cash	(36,495)	(96,060)	58,474
Cash and restricted cash, beginning of period	56,560	152,620	94,146
Cash and restricted cash, end of period	20,065	56,560	152,620
Supplemental disclosures of cash flow information
Income taxes paid (Note 10)	153,974	243,500	143,973
Interest paid	$ 86,532	$ 79,062	$ 78,704