Investments in Equity Securities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 1,145,040	$ 1,203,788
Fair Value
Debt Securities, Available-for-sale [Line Items]
Cost	863,278	941,974
Gross Unrealized, Gains	331,158	346,697
Gross Unrealized, Losses	(49,396)	(84,883)
Equity securities	1,145,040	1,203,788
Fair Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Cost	517,215	612,479
Gross Unrealized, Gains	208,118	223,981
Gross Unrealized, Losses	(42,656)	(76,293)
Equity securities	682,677	760,167
Fair Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Cost	346,063	329,495
Gross Unrealized, Gains	123,040	122,716
Gross Unrealized, Losses	(6,740)	(8,590)
Equity securities	462,363	443,621
Carrying Value
Debt Securities, Available-for-sale [Line Items]
Equity securities	1,145,040	1,203,788
Carrying Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Equity securities	682,677	760,167
Carrying Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 462,363	$ 443,621