Segment Information (Schedule of Additional Business Segment Information) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Assets	$ 1,248,822	$ 1,162,460
Specialty Commercial Segment [Member]
Segment Reporting Information [Line Items]
Assets	814,220	734,763
Standard Commercial Segment [Member]
Segment Reporting Information [Line Items]
Assets	167,274	164,295
Personal Segment [Member]
Segment Reporting Information [Line Items]
Assets	243,031	241,686
Corporate [Member]
Segment Reporting Information [Line Items]
Assets	$ 24,297	$ 21,716