Property, Plant and Equipment - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 876	$ 561
Interest costs capitalized	0	1,348
Construction in progress
Property, Plant and Equipment [Line Items]
Interest costs capitalized	0	1,300
Payroll costs	$ 300	$ 400