Segment Information (Schedule of Additional Business Segment Information) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Assets	$ 1,517,543	$ 1,485,533
Specialty Commercial Segment [Member]
Segment Reporting Information [Line Items]
Assets	1,117,546	1,104,953
Standard Commercial Segment [Member]
Segment Reporting Information [Line Items]
Assets	198,785	183,689
Personal Segment [Member]
Segment Reporting Information [Line Items]
Assets	138,897	133,310
Corporate [Member]
Segment Reporting Information [Line Items]
Assets	$ 62,315	$ 63,581