Property and Equipment - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation	$ 286	$ 153	$ 877	$ 325
Accumulated depreciation	1,999		1,999		$ 1,151
Inventory
Property, Plant and Equipment [Line Items]
Accumulated depreciation	57		57
Prepaid expenses and other assets
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 90		$ 90