Business Acquisitions - Table (Details) $ in Thousands, € in Millions	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2015 EUR (€)	Sep. 30, 2015 USD ($)
Business Acquisition [Line Items]
Finite Lived Customer Lists, Gross	$ 74,989	$ 76,581
Other Finite Lived Intangible Assets, Gross	5,840	6,114
Goodwill	$ 83,333	$ 86,034	$ 80,804
Mining [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price				$ 1,900
Verkol [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price					€ 37.7	$ 41,400