Historical Loss and LAE Development - Reserve Development (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
(Favorable)/Unfavorable Reserve Development
Prior accident years	$ (122,579)	$ (125,463)	$ (101,053)
Casualty Segment
(Favorable)/Unfavorable Reserve Development
Prior accident years	(87,225)	(108,632)	(75,075)
Property segment
(Favorable)/Unfavorable Reserve Development
Prior accident years	(24,927)	(10,981)	(13,019)
Surety Segment
(Favorable)/Unfavorable Reserve Development
Prior accident years	$ (10,427)	$ (5,850)	$ (12,959)