Segment Information (Schedule of Additional Business Segment Information) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Assets	$ 1,520,208	$ 1,496,717
Specialty Commercial Segment [Member]
Segment Reporting Information [Line Items]
Assets	1,113,020	1,116,137
Standard Commercial Segment [Member]
Segment Reporting Information [Line Items]
Assets	199,999	183,689
Personal Segment [Member]
Segment Reporting Information [Line Items]
Assets	139,530	133,310
Corporate [Member]
Segment Reporting Information [Line Items]
Assets	$ 67,659	$ 63,581