Segment Information (Schedule of Segment Reporting Additional Information by Segment) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets	$ 1,231,126	$ 1,162,460
Specialty Commercial Segment [Member]
Assets	810,133	734,763
Standard Commercial Segment [Member]
Assets	162,152	164,295
Personal Segment [Member]
Assets	232,441	241,686
Corporate [Member]
Assets	26,400	21,716
Parent Company [Member]
Assets	$ 364,818	$ 379,079