Acquisitions (Schedule of Merger-Related Expense) (Details) - FNBC Transaction [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Personnel expense	$ 3,662
Net occupancy and equipment expense	777
Professional services expense	9,681
Data processing expense	974
Other real estate	(1,511)
Advertising expense	1,389
Other expense	4,398
Total merger-related expenses	$ 19,370