Business Acquisitions - Table (Details) $ in Thousands, € in Millions, SEK in Millions, AUD in Millions	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2015 AUD	Dec. 31, 2015 USD ($)	Sep. 30, 2015 EUR (€)	Sep. 30, 2015 USD ($)	Dec. 31, 2014 AUD	Dec. 31, 2014 SEK	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Finite Lived Customer Lists, Gross	$ 76,581	$ 71,454
Other Finite Lived Intangible Assets, Gross	6,114	6,023
Goodwill	$ 86,034	80,804			$ 79,111
Mining [Member]
Business Acquisition [Line Items]
Present Value of Holdback				AUD (0.3)	$ (200)
Business Acquisition, Cost of Acquired Entity, Purchase Price			$ 1,900					AUD 2.9		$ 2,400
Binol [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price									SEK 136.5	$ 18,500
Verkol [Member]
Business Acquisition [Line Items]
Long-term Debt						€ (2.2)	$ (2,400)
Cash Acquired						14.1	15,400
Business Acquisition, Cost of Acquired Entity, Purchase Price						€ 37.7	$ 41,400
2016 Acquisitions [Member]
Business Acquisition [Line Items]
Current Assets		3,443
Propery, Plant & Equipment		2,574
Finite Lived Customer Lists, Gross		5,041
Finite Lived Trademarks, Gross		2,543
Other Finite Lived Intangible Assets, Gross		127
Goodwill		3,355
Total Assets Purchased		17,083
Other Current Liabilities		(1,198)
Other Non-Current Liabilities		(2,019)
Total Liabilities Assumed		(3,217)
Business Acquisition, Cost of Acquired Entity, Purchase Price, Gross		13,866
Cash Acquired		105
Business Acquisition, Cost of Acquired Entity, Purchase Price		$ 13,761