Segment Reporting Schedule of Revenues from External Customers and Long-Lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 173,207	$ 182,146	$ 175,475	$ 170,018	$ 170,111	$ 162,887	$ 158,212	$ 156,609	$ 700,846	$ 647,819	$ 590,232
Property, plant and equipment, ret	122,917				123,098				122,917	123,098	129,882
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									324,073	283,969	224,642
Property, plant and equipment, ret	65,073				63,812				65,073	63,812	71,388
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									34,633	30,131	20,537
Property, plant and equipment, ret	9,567				9,725				9,567	9,725	10,497
Other Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									342,140	333,719	345,053
Property, plant and equipment, ret	$ 48,277				$ 49,561				$ 48,277	$ 49,561	$ 47,997