Segment And Geographic Information (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of operating segments | segment	1
Total sales	$ 1,228,179	$ 1,225,456	$ 1,243,862
Property and equipment, net	260,456	257,853
Outside The United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total sales	773,000	762,000	780,000
Property and equipment, net	$ 133,000	$ 138,000	$ 145,000