Summary of Significant Accounting Policies - Deferred Policy Acquisition Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Recorded asset at beginning of year	$ 91,446
Recorded asset at end of year	104,225	$ 91,446
Property and casualty business
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Recorded asset at beginning of year	91,446	87,094	$ 94,292
Underwriting costs deferred	225,854	207,784	203,054
Amortization of deferred policy acquisition costs	(213,075)	(203,432)	(210,252)
Recorded asset at end of year	$ 104,225	$ 91,446	$ 87,094