SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Condensed Balance Sheets (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Assets
Fixed income, available-for-sale	$ 5,851,689	$ 5,723,113
Investments	5,867,560	5,738,734
Cash and cash equivalents	229,485	363,666
Accrued investment income	61,064	58,774
Total assets	6,547,235	6,538,380
Liabilities:
Senior notes	644,667	643,196
Other liabilities	147,171	160,009
Total liabilities	1,374,860	1,466,363
Shareholders’ equity:
Common stock	248,449	371,353
Paid-in capital	1,808,236	1,808,113
Treasury stock, at cost	0	(1,384,293)
Accumulated other comprehensive income (loss), net of tax	(288,162)	(316,281)
Retained earnings	3,403,852	4,593,125
Total shareholders' equity	5,172,375	5,072,017	$ 4,642,740
Total liabilities and shareholders' equity	$ 6,547,235	$ 6,538,380
Parenthetical information [Abstract]
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	248,449,000	371,353,000
Common stock, shares outstanding (in shares)	248,449,000	272,494,000
Treasury stock, shares at cost (in shares)	0	98,859,000
Fixed income
Assets
Fixed income, available-for-sale	$ 5,511,564	$ 5,601,540
Parenthetical information [Abstract]
Fixed income, amortized cost	5,838,145	5,939,483
Short-Term Investments
Assets
Fixed income, available-for-sale	340,125	121,573
Parenthetical information [Abstract]
Fixed income, amortized cost	339,978	121,539
Parent Company
Assets
Investments	925,880	709,333
Cash and cash equivalents	149,944	208,600
Investment in subsidiaries, at equity in net assets	4,767,074	4,777,121
Accounts receivable - affiliates	2,512	2,860
Income taxes - current and deferred	2,221	34,597
Accrued investment income	8,165	5,975
Total assets	5,855,796	5,738,486
Liabilities:
Senior notes	644,667	643,196
Accrued interest	12,797	12,797
Other liabilities	25,957	10,476
Total liabilities	683,421	666,469
Shareholders’ equity:
Common stock	248,449	371,353
Paid-in capital	1,808,236	1,808,113
Treasury stock, at cost	0	(1,384,293)
Accumulated other comprehensive income (loss), net of tax	(288,162)	(316,281)
Retained earnings	3,403,852	4,593,125
Total shareholders' equity	5,172,375	5,072,017
Total liabilities and shareholders' equity	$ 5,855,796	$ 5,738,486
Parenthetical information [Abstract]
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	248,449,000	371,353,000
Common stock, shares outstanding (in shares)	248,449,000	272,494,000
Treasury stock, shares at cost (in shares)	0	98,859,000
Parent Company | Fixed income
Assets
Fixed income, available-for-sale	$ 546,179	$ 598,420
Parenthetical information [Abstract]
Fixed income, amortized cost	544,456	597,944
Parent Company | Short-Term Investments
Assets
Fixed income, available-for-sale	379,701	110,913
Parenthetical information [Abstract]
Fixed income, amortized cost	$ 379,603	$ 110,889