Property, Plant and Equipment, and Leases - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Apr. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, at cost	$ 46,100					$ 35,735
Accumulated depreciation	(21,834)					(16,775)
Property, plant and equipment, net	24,266	$ 24,536	$ 24,931		$ 18,474	18,960	$ 18,974	$ 19,050	$ 19,230
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, at cost	6,405					6,320
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, at cost	38,454			$ 6,900		27,379
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, at cost	$ 1,241					$ 2,036