Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities
Net income	$ 604,440	$ 603,119	$ 742,934
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Purchases of residential mortgage loans held for sale	(1,649,063)	(220,885)	(3,890)
Proceeds from sales of residential mortgage loans held for sale	338,862	172,573	0
Principal payments from residential mortgage loans held for sale	29,952	17,064	393
Net (gains) losses on investments and other financial instruments	10,114	(10,241)	80,733
Net (gains) losses on consolidated VIE assets and liabilities	1,169	0	0
Loss on extinguishment of debt	4,275	0	0
Amortization and impairment of goodwill and other acquired intangible assets	0	15,285	4,308
Depreciation, other amortization, and other impairments, net	78,750	73,632	72,267
Deferred income tax provision	162,275	165,001	206,925
Change in:
Accrued investment income	(7,350)	(5,690)	(7,281)
Accounts and notes receivable	(1,482)	(1,618)	4,210
Reinsurance recoverable	(10,524)	(276)	42,263
Deferred policy acquisition costs	972	(258)	(2,143)
Prepaid federal income tax	(170,760)	(153,952)	(242,245)
Other assets	28,105	37,960	65,744
Unearned premiums	(37,059)	(46,083)	(57,611)
Reserve for losses and LAE	(9,822)	(56,695)	(401,799)
Reinsurance funds withheld	(8,581)	(21,503)	(76,011)
Other liabilities	(27,845)	(37,999)	(40,499)
Net cash provided by (used in) operating activities	(663,572)	529,434	388,298
Proceeds from sales of:
Available for sale securities	511,647	331,880	399,371
Trading securities	0	9,123	8,868
Equity securities	45,747	67,953	8,004
Proceeds from redemptions of:
Available for sale securities	903,395	498,081	789,929
Trading securities	17,081	1,707	102,121
Purchases of:
Available for sale securities	(1,344,925)	(933,264)	(1,414,966)
Equity securities	(23,425)	(8,334)	(24,637)
Sales, redemptions and (purchases) of:
Short-term investments, net	153,243	(251,662)	150,694
Other assets and other invested assets, net	1,115	(45)	(6,887)
Principal payments from securitized residential mortgage loans held for investment	67,041	0	0
Additions to property and equipment	(3,173)	(16,281)	(17,672)
Net cash provided by (used in) investing activities	327,746	(300,842)	(5,175)
Cash flows from financing activities
Dividends and dividend equivalents paid	(151,961)	(145,908)	(135,437)
Issuance of common stock	928	1,755	1,341
Repurchases of common stock	(225,059)	(133,314)	(400,195)
Issuance of senior notes	616,745	0	0
Redemption of senior notes	(977,079)	0	0
Issuance of securitized nonrecourse debt	766,336	0	0
Repayments of securitized nonrecourse debt	(67,041)	0	0
Proceeds (repayments) related to cash collateral for loaned securities, net	(23,641)	49,629	51,083
Proceeds from secured borrowings	2,188,897	761,560	381,887
Repayments of secured borrowings	(1,770,080)	(797,905)	(377,048)
Credit facility commitment fees paid	(812)	(904)	(814)
Net cash provided by (used in) financing activities	357,233	(265,087)	(479,183)
Increase (decrease) in cash and restricted cash	21,407	(36,495)	(96,060)
Cash and restricted cash, beginning of period	20,065	56,560	152,620
Cash and restricted cash, end of period	41,472	20,065	56,560
Supplemental disclosures of cash flow information
Income taxes paid (Note 10)	172,647	153,974	243,500
Interest paid	107,692	86,532	79,062
Supplemental noncash information
Transfer from residential mortgage loans held for sale to securitized residential mortgage loans held for investment	778,523	0	0
Retention of mortgage servicing rights from residential mortgage loan sales	2,615	41	0
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	$ 1,242	$ 1,097	$ 4,804