Schedule VI - Supplemental Information Concerning Insurance Operations - (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Claim and claim adjustment expenses incurred related to current year	$ 358,952	$ 262,118	$ 231,133
Claim and claim adjustment expenses incurred related to prior year	17,551	10,971	(2,717)
Property and Casualty Insurance
Supplemental Information for Property, Casualty Insurance Underwriters [Line Items]
Deferred acquisition costs	25,405	56,136	39,436
Loss and loss adjustment expense reserves	540,367	324,362	296,230
Unearned premiums	366,789	360,870	281,992
Earned premiums	364,134	363,652	355,257
Net investment income	11,786	15,901	12,460
Claim and claim adjustment expenses incurred related to current year	358,898	262,109	231,133
Claim and claim adjustment expenses incurred related to prior year	17,551	10,971	(2,717)
Supplemental Information for Property, Casualty Insurance Underwriters, Amortization of Deferred Policy Acquisition Costs	121,524	96,885	97,873
Paid claims and claims adjustment expense	354,143	254,806	230,752
Supplemental Information for Property, Casualty Insurance Underwriters, Premiums Written	$ 236,623	$ 377,879	$ 365,032