Business acquisition - Change in contingent consideration (Details) - Abveris - USD ($) $ in Thousands	9 Months Ended	10 Months Ended
	Jun. 30, 2023	Sep. 30, 2022
Business Combination, Contingent Consideration Arrangements, Change In Amount Of Contingent Consideration, Liability [Roll Forward]
Balance at December 1, 2021 – acquisition date	$ 7,193	$ 20,664
Change in fair value during the period	(5,426)	(13,471)
Settlement during the period	(1,767)
Balance at June 30, 2023	0	7,193
Contingent consideration
Business Combination, Contingent Consideration Arrangements, Change In Amount Of Contingent Consideration, Liability [Roll Forward]
Balance at December 1, 2021 – acquisition date	2,100	8,500
Change in fair value during the period	(2,100)	(6,400)
Settlement during the period	0
Balance at June 30, 2023	0	2,100
Holdbacks
Business Combination, Contingent Consideration Arrangements, Change In Amount Of Contingent Consideration, Liability [Roll Forward]
Balance at December 1, 2021 – acquisition date	5,093	12,164
Change in fair value during the period	(3,326)	(7,071)
Settlement during the period	(1,767)
Balance at June 30, 2023	$ 0	$ 5,093