Reserves for Losses and Loss Adjustment Expenses (Incurred and Paid Claims Development - Runoff) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) claim	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable (favorable) net prior year development	$ 6,040	$ 58,288
Incurred claims and claim adjustment expenses related to current year	269,204	326,919
Total incurred	275,244	406,907
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	177,571	185,407
Paid claims and allocated claim adjustment expenses related to current year	101,475	113,312
Total paid	279,046	320,419
Liabilities for unpaid claims and claim adjustment expenses, net of reinsurance	428,766	432,568	$ 346,080
Loss Adjustment Expenses Recognized In 2012 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years										$ 1,181
Workers Compensation Business Unit [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total incurred	35,671
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Total paid	34,641
All outstanding liabilities before 2012, net of reinsurance	723
Liabilities for unpaid claims and claim adjustment expenses, net of reinsurance	1,753
Workers Compensation Business Unit [Member] | Loss Adjustment Expenses Recognized In 2012 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable (favorable) net prior year development		2,773	2,752	$ 2,752	$ 2,636	$ 2,821	$ 3,358	$ 3,597	$ 4,469	$ 4,804
Incurred claims and claim adjustment expenses related to current year	2,773
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 91
Cumulative number of reported claims | claim	714
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 2,675	2,675	2,675	2,602	2,600	2,583	2,594	2,411	2,107
Workers Compensation Business Unit [Member] | Loss Adjustment Expenses Recognized In 2013 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable (favorable) net prior year development		9,483	9,486	9,472	9,257	9,257	9,713	10,143	9,069
Incurred claims and claim adjustment expenses related to current year	9,470
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 237
Cumulative number of reported claims | claim	1,337
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 9,070	9,050	9,010	8,961	8,809	8,350	7,882	6,825	$ 3,737
Workers Compensation Business Unit [Member] | Loss Adjustment Expenses Recognized In 2014 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable (favorable) net prior year development		10,292	10,463	10,452	10,076	9,762	9,338	9,208
Incurred claims and claim adjustment expenses related to current year	10,127
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 431
Cumulative number of reported claims | claim	1,027
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 9,571	9,487	9,323	9,210	9,004	7,970	5,972	$ 2,933
Workers Compensation Business Unit [Member] | Loss Adjustment Expenses Recognized in 2015 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable (favorable) net prior year development		8,526	8,420	8,892	8,624	7,277	8,605
Incurred claims and claim adjustment expenses related to current year	8,508
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 164
Cumulative number of reported claims | claim	822
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 8,542	8,512	8,495	8,049	7,328	5,744	$ 2,528
Workers Compensation Business Unit [Member] | Loss Adjustment Expenses Recognized in 2016 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable (favorable) net prior year development		4,425	4,416	4,365	4,733	3,553
Incurred claims and claim adjustment expenses related to current year	$ 4,425
Cumulative number of reported claims | claim	462
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 4,425	4,425	4,418	3,743	2,550	$ 1,732
Workers Compensation Business Unit [Member] | Loss Adjustment Expenses Recognized in 2017 [Member]
Liability For Unpaid Claims and Claims Adjustment Expense, Incurred Claims [Abstract]
Total unfavorable (favorable) net prior year development		403	415	465	450
Incurred claims and claim adjustment expenses related to current year	368
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 10
Cumulative number of reported claims | claim	66
Liability For Unpaid Claims and Claims Adjustment Expense, Claims Paid [Abstract]
Paid claims and allocated claim adjustment expenses related to prior years	$ 358	$ 282	$ 203	$ 171	$ 111