Collaboration and Research Arrangements - Summary of Changes in Contract Assets and Liabilities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Disaggregation Of Revenue [Line Items]
Contract liabilities, Balance at Beginning of Period	$ 10,202
Contract liabilities, Additions	20,158
Contract liabilities, Deduction	1,982
Contract liabilities, Balance at End of Period	28,378
Incyte
Disaggregation Of Revenue [Line Items]
Contract liabilities, Balance at Beginning of Period	10,202
Contract liabilities, Additions	158
Contract liabilities, Deduction	1,982
Contract liabilities, Balance at End of Period	8,378
GBT [Member]
Disaggregation Of Revenue [Line Items]
Contract liabilities, Balance at Beginning of Period	0
Contract liabilities, Additions	20,000
Contract liabilities, Deduction	0
Contract liabilities, Balance at End of Period	20,000
Billed and unbilled receivables from collaboration partners
Disaggregation Of Revenue [Line Items]
Contract assets, Balance at Beginning of Period	0
Contract assets, Additions	20,158
Contract assets, Deduction	0
Contract assets, Balance at End of Period	$ 20,158