Property, Plant and Equipment, Net (Details) $ in Thousands		12 Months Ended			17 Months Ended
	Jul. 31, 2018 USD ($) ft²	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)
Property, Plant and Equipment, Net
Property, Plant and Equipment, Gross		$ 61,365	$ 64,643		$ 61,365
Less: Accumulated depreciation and amortization		(4,441)	(1,847)		(4,441)
Property, plant and equipment, net		56,924	62,796		56,924	$ 17,654
Depreciation and amortization expense		3,000	1,300	$ 400
Maximum
Property, Plant and Equipment, Net
Capitalized interest cost		700
Laboratory equipment
Property, Plant and Equipment, Net
Property, Plant and Equipment, Gross		16,079	7,122		16,079
Land
Property, Plant and Equipment, Net
Property, Plant and Equipment, Gross		1,300	1,300		1,300
Purchases and additions	$ 1,300
Leasehold improvements
Property, Plant and Equipment, Net
Property, Plant and Equipment, Gross		445	117		445
Computers and software
Property, Plant and Equipment, Net
Property, Plant and Equipment, Gross		1,051	276		1,051
Furniture and fixtures
Property, Plant and Equipment, Net
Property, Plant and Equipment, Gross		1,228			1,228
Construction-in-progress
Property, Plant and Equipment, Net
Property, Plant and Equipment, Gross		41,262	$ 55,828		41,262
Purchases and additions	$ 6,700	5,900
Build-to-suit lease
Property, Plant and Equipment, Net
Derecognition of property and equipment						$ 45,100
Manufacturing facility
Property, Plant and Equipment, Net
Square footing of facility acquired | ft²	135,000
Purchases and additions	$ 8,000
Clinical Supply | Construction-in-progress
Property, Plant and Equipment, Net
Purchases and additions		$ 26,300			$ 28,400