Segment And Geographic Information (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) segment	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments | segment			1
Total sales	$ 318,609	$ 306,105	$ 618,714	$ 593,282
Property and equipment, net	256,761		256,761		$ 260,456
Outside The United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales	204,000	$ 198,000	393,000	$ 381,000
Property and equipment, net	$ 133,000		$ 133,000		$ 133,000