Revenue recognition (Details) - USD ($) $ in Millions	1 Months Ended		3 Months Ended		6 Months Ended		30 Months Ended
	Sep. 30, 2021	Dec. 31, 2019	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative
Contract assets			$ 0.1		$ 0.1		$ 0.1	$ 0.6
Contract liabilities			2.8		2.8		2.8	1.4
Revenue recognized from customer contract liability			0.4	$ 0.1	0.8	$ 1.1
KBI BioPharma, Inc. | Collaborative Arrangements
Collaborative Arrangement and Arrangement Other than Collaborative
Contract liabilities			0.5		0.5		0.5	$ 1.2
Contract term (years)	3 years	4 years
Upfront payment received							0.8
Aggregate milestone payments			2.8		2.8		2.8
Cumulative proceed from collaborative agreements			$ 2.3		$ 2.3		$ 2.3
Collaborative arrangement, collaboration agreement fee	$ 0.3