Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets, Net [Abstract]
Acquired and in-licensed rights	$ 8,712	$ 8,712
Less: accumulated amortization	(1,730)	(1,330)
Total intangible asset, net	$ 6,982	$ 7,382
Estimated useful life	11 years