Significant Changes Due To Topic 606 (Significant Changes in Contract Assets and Contract Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Significant Changes Due To Topic 606 [Abstract]
Contract assets recognized, net of reclassification to accounts receivable	$ 2,645
Net Change in Contract Asset	2,645	$ 1,117	$ (1,082)
Reclassification of beginning contract liabilities to revenue, as a result of performance obligations satisfied	312
Cash received in advance and not recognized as revenue	(457)
Net Change in Contract Liability	$ (145)