Summary of Significant Accounting Policies - PP&E, ARO and Other (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment
Construction in progress	$ 14,930	$ 4,284
Interest costs capitalized	0	0
Asset Retirement Obligations
ARO included in other liabilities and accrued expenses	1,582	1,838
Amount of assets associated with AROs not fully depreciated	910
Amount spent on AROs	377	311
Accretion expense recognized on AROs	73	70	$ 60
Other Assets
Deferred financing costs	35	49
Other	678	93
Total	713	142
Environmental Expenditures
Capital expenditures related to environmental matters	440	$ 477	$ 455
Minimum
Asset Retirement Obligations
Estimated annual expenditures in years 2018 through 2022 relating to AROs	100
Maximum
Asset Retirement Obligations
Estimated annual expenditures in years 2018 through 2022 relating to AROs	$ 200
Buildings and building improvements | Minimum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	3 years
Buildings and building improvements | Maximum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	20 years
Machinery and equipment | Minimum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	2 years
Machinery and equipment | Maximum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	20 years
Furniture and fixtures | Minimum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	3 years
Furniture and fixtures | Maximum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	10 years
Automotive equipment. | Minimum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	3 years
Automotive equipment. | Maximum
Property, Plant and Equipment
Estimated useful lives of property, plant and equipment	10 years