Commitments and Contingencies - Schedule of Gross Assets under Capital Lease (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Capital Leased Assets [Line Items]
Total gross assets under capital lease	$ 13,562	$ 13,159
Land, Buildings and Improvements
Capital Leased Assets [Line Items]
Total gross assets under capital lease	9,133	9,133
Machinery and Equipment
Capital Leased Assets [Line Items]
Total gross assets under capital lease	$ 4,429	$ 4,026