Reserves for Losses and Loss Adjustment Expenses (Reconciliation of Incurred and Paid Claims to Liability for Unpaid Losses and LAE) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated loss adjustment expense, net of reinsurance	$ 418,057	$ 431,821
Reinsurance recoverable on unpaid claims	387,915	349,585
Unallocated claims adjustment expenses	10,709	8,362
Total gross liability for unpaid claims and claim adjustment expenses	816,681	789,768	$ 620,355
Commercial Auto business units [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated loss adjustment expense, net of reinsurance	190,207	218,999
Reinsurance recoverable on unpaid claims	85,398	91,040
Unallocated claims adjustment expenses	1,589	1,850
E&S Casualty business unit [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated loss adjustment expense, net of reinsurance	104,001	97,302
Reinsurance recoverable on unpaid claims	141,746	122,341
Unallocated claims adjustment expenses	3,694	1,681
Commercial Accounts business unit [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated loss adjustment expense, net of reinsurance	60,511	59,603
Reinsurance recoverable on unpaid claims	27,464	20,464
Unallocated claims adjustment expenses	2,448	2,643
General Aviation and Satellite Component [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated loss adjustment expense, net of reinsurance	3,276	2,448
Reinsurance recoverable on unpaid claims	13,385	10,143
Unallocated claims adjustment expenses	99	104
Workers Compensation Business Unit [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated loss adjustment expense, net of reinsurance	1,753	2,226
Reinsurance recoverable on unpaid claims	1,155	1,184
Unallocated claims adjustment expenses	170	170
Specialty Commercial Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated loss adjustment expense, net of reinsurance	7,408	5,644
Reinsurance recoverable on unpaid claims	236	968
Unallocated claims adjustment expenses	91	61
Personal Segment [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated loss adjustment expense, net of reinsurance	17,393	18,597
Reinsurance recoverable on unpaid claims	1,707	5,613
Unallocated claims adjustment expenses	1,625	1,250
Property [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Liabilities for unpaid losses and allocated loss adjustment expense, net of reinsurance	33,508	27,002
Reinsurance recoverable on unpaid claims	116,824	97,832
Unallocated claims adjustment expenses	$ 993	$ 603