Segment Reporting Schedule of Revenues from External Customers and Long-Lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net	$ 182,723	$ 197,265	$ 203,889	$ 213,643	$ 278,622	$ 276,135	$ 267,562	$ 262,903	$ 797,520	$ 1,085,222	$ 1,073,508
Property, Plant and Equipment, Net	143,211				149,014				143,211	149,014	138,824
Income Before Interest Expense and Taxes	23,642	$ 46,818	$ 47,893	$ 42,717	90,450	$ 89,120	$ 84,134	$ 82,827	161,070	346,531	333,419
Other Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net									414,805	464,335	478,414
Property, Plant and Equipment, Net	50,526				49,209				50,526	49,209	47,759
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net									338,907	515,643	487,252
Property, Plant and Equipment, Net	80,603				83,748				80,603	83,748	73,870
CANADA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net									43,808	105,244	107,842
Property, Plant and Equipment, Net	$ 12,082				$ 16,057				$ 12,082	$ 16,057	$ 17,195