Segment Information (Schedule of Property, Plant and Equipment by Geographical Location) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 2,122,297	$ 2,180,270	$ 2,325,181
United States
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	2,111,273	2,169,246	2,314,157
CANADA
Segment Reporting Information [Line Items]
Property, Plant and Equipment, Net	$ 11,024	$ 11,024	$ 11,024