Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies [Abstract]
Operating leases, rent expense, net	$ 2,800	$ 2,500	$ 2,200
Guaranty association assessments	$ 36	$ 100