Operating Expenses (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 28,337	$ 30,983	$ 35,374
Amortization expense	24,357	9,878	6,658
Software [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	1,207	2,880	4,340
Amortization expense	$ 11,662	$ 7,218	$ 4,680