Investments in Equity Securities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 1,048,126	$ 1,090,347
Fair Value
Debt Securities, Available-for-sale [Line Items]
Cost	949,553	949,332
Gross Unrealized, Gains	168,682	194,881
Gross Unrealized, Losses	(70,109)	(53,866)
Equity securities	1,048,126	1,090,347
Fair Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Cost	604,288	664,997
Gross Unrealized, Gains	157,761	191,806
Gross Unrealized, Losses	(60,382)	(18,749)
Equity securities	701,667	838,054
Fair Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Cost	345,265	284,335
Gross Unrealized, Gains	10,921	3,075
Gross Unrealized, Losses	(9,727)	(35,117)
Equity securities	346,459	252,293
Carrying Value
Debt Securities, Available-for-sale [Line Items]
Equity securities	1,048,126	1,090,347
Carrying Value | Common stock
Debt Securities, Available-for-sale [Line Items]
Equity securities	701,667	838,054
Carrying Value | Preferred stocks
Debt Securities, Available-for-sale [Line Items]
Equity securities	$ 346,459	$ 252,293