Derivative Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Maximum net exposure to company									$ 724
Sales	$ 57,307	$ 55,686	$ 45,881	$ 53,267	$ 52,677	$ 45,774	$ 30,680	$ 41,556	212,141	$ 170,687	$ 148,189
Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Sales									256	$ (450)
Reclassification Out Of Accumulated Other Comprehensive Income [Member] \| Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Sales									$ 256