Property, Plant and Equipment - Depreciation and Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 111,292	$ 122,102	$ 114,215
Services
Property, Plant and Equipment [Line Items]
Depreciation and amortization	93,280	102,212	101,260
Products
Property, Plant and Equipment [Line Items]
Depreciation and amortization	4,354	4,971	4,254
General and administrative expenses
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 13,658	$ 14,919	$ 8,701