Property, Plant and Equipment - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 900	$ 500	$ 1,778	$ 1,133
Interest costs capitalized			0	477
Construction in progress
Property, Plant and Equipment [Line Items]
Interest costs capitalized		1,500		2,800
Payroll costs	$ 300	$ 700	$ 600	$ 1,100