Business Combinations, Goodwill and Intangible Assets (Changes in Carrying Amount of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Beginning of Year	$ 54,058	$ 20,536	$ 20,536
Acquired Goodwill	0	33,522	0
Impairment	0	0	0
End of Year	$ 54,058	$ 54,058	$ 20,536