Investments - Pretax Net Realized Investment Gains (Losses) and Net Changes in Unrealized Gains (Losses) on Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Net realized gains (losses):
Net realized gains (losses) - Available-for-sale	$ (5,276)	$ (3,641)	$ (2,997)
Net realized gains (losses) - Equity securities	30,792	22,232	20,287
Net realized gains (losses) - Investment in unconsolidated investees	(42)	14,084	570,952
Net realized gains (losses) - Other	(5,508)	(157)	273
Total net realized gains (losses)	19,966	32,518	588,515
Net unrealized gains (losses) on equity securities	81,734	64,787	(121,037)
Unrealized gains (losses) recognized in other comprehensive earnings - Available-for-sale	(16,822)	79,782	(341,944)
Unrealized gains (losses) recognized in other comprehensive earnings - Investment in unconsolidated investees	7,539	(290)	(10,994)
Unrealized gains (losses) recognized in other comprehensive earnings - Other	(109)	(33)	(102)
Total unrealized gains (losses) recognized in other comprehensive earnings	(9,392)	79,459	(353,040)
Net realized gains (losses) and changes in unrealized gains (losses) on investments	92,308	176,764	114,438
Equity Securities
Net realized gains (losses):
Net unrealized gains (losses) on equity securities	82,275	65,655	(118,912)
Other
Net realized gains (losses):
Net unrealized gains (losses) on equity securities	$ (541)	$ (868)	$ (2,125)