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Investments - Schedule of Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Net Investment Income [Line Items]
Net investment income earned	$ 457,051	$ 388,650	$ 288,155
Fixed income securities
Net Investment Income [Line Items]
Net investment income earned	389,198	345,886	259,918
CMLs
Net Investment Income [Line Items]
Net investment income earned	12,448	9,336	5,555
Equity securities
Net Investment Income [Line Items]
Net investment income earned	18,295	9,395	13,554
Short-term investments
Net Investment Income [Line Items]
Net investment income earned	20,274	14,818	3,997
Alternative investments
Net Investment Income [Line Items]
Net investment income earned	37,053	26,777	23,003
Other investments
Net Investment Income [Line Items]
Net investment income earned	864	650	258
Investment expenses
Net Investment Income [Line Items]
Investment expenses	$ (21,081)	$ (18,212)	$ (18,130)

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