Property Plant and Equipment - Summary of Property and Equipment at Cost and Related Accumulated Depreciation (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 5,763	$ 5,926
Less accumulated depreciation and amortization	(427)	(230)
Total property and equipment, net	5,336	5,696
Furniture And Fixtures [Member]
Property Plant And Equipment [Line Items]
Property and equipment, at cost	1,611	1,611
Computer Equipment And Software [Member]
Property Plant And Equipment [Line Items]
Property and equipment, at cost	139	102
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 4,013	$ 4,213