Schedule IV - Reinsurance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Insurance Earned Premiums
Gross Amount	$ 845,102	$ 836,759	$ 818,804
Ceded to Other Companies	89,178	87,368	76,886
Assumed from Other Companies	32,853	32,196	32,502
Net Amount	788,777	781,587	774,420
Property and Casualty Insurance
Insurance Earned Premiums
Gross Amount	845,102	836,759	818,804
Ceded to Other Companies	89,178	87,368	76,886
Assumed from Other Companies	32,853	32,196	32,502
Net Amount	$ 788,777	$ 781,587	$ 774,420
Percentage of Amount Assumed to Net	4.20%	4.10%	4.20%