Collaboration agreements - Contract Assets and Liabilities (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Contract liabilities
Balance at Beginning of Period			$ 147,653,000	$ 3,944,000
Additions			808,000	40,000,000
Deductions			13,764,000	6,030,000
Balance at End of Period	$ 134,697,000	$ 37,914,000	134,697,000	37,914,000
Amounts included in the contract liability at the beginning of the period	8,497,000	4,284,000	13,607,000	21,000
Janssen Agreement
Contract liabilities
Balance at Beginning of Period			15,800,000
Balance at End of Period	8,700,000		8,700,000
Contract assets	0	0	0	0
GSK Agreement
Contract liabilities
Balance at Beginning of Period			98,000,000
Balance at End of Period	96,700,000		96,700,000
Contract assets	0	0	0	0
2022 Merck Research Collaboration & License Agreement
Contract liabilities
Balance at Beginning of Period			30,000,000
Balance at End of Period	25,400,000		25,400,000
Contract assets	0	0	0	0
2014 & 2018 Collaboration and Commercial License Agreement and Supply Agreement Merck KGaA
Contract liabilities
Balance at Beginning of Period			3,900,000
Balance at End of Period	3,900,000		3,900,000
Contract assets	$ 0	$ 0	$ 0	$ 0