Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross, excluding capital leased assets	$ 327,059	$ 266,781
Accumulated depreciation	(130,814)	(108,425)
Property, plant and equipment, net, excluding capital leased assets	196,245	158,356
Construction in progress	117,173	80,048
Property, plant and equipment, net	313,418	238,404
Depreciation	23,700	22,200	$ 19,900
Outside the United States
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net	82,800	65,100
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross, excluding capital leased assets	17,846	17,410
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross, excluding capital leased assets	106,316	88,825
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross, excluding capital leased assets	$ 202,897	$ 160,546