Commitments and Contingencies (Schedule for Unfunded Commitments) (Details) - Allowance for Credit Loss [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 2,287	$ 2,119	$ 5,151
Provision (benefit)	75	168	(3,032)
Ending balance	$ 2,362	$ 2,287	$ 2,119