Leases - Summary of lease cost (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Jun. 30, 2021
Leases [Abstract]
Operating lease cost	$ 2.8	$ 3.0	$ 7.7	$ 9.8
Short-term lease cost	0.9	0.7	2.5	2.3
Variable lease cost	0.2	0.0	0.5	0.2
Sublease income	(0.2)	(0.3)	(0.7)	(0.5)
Total lease cost	3.7	3.4	10.0	11.8
Operating cash flow payments from operating leases	2.7	3.1	8.2	10.2
Non-cash ROU assets obtained in exchange for lease obligations	$ 0.2	$ 0.0	$ 15.5	$ 1.4
Weighted-average remaining lease term - operating leases	8 years 8 months 12 days		8 years 8 months 12 days		8 years 4 months 24 days
Weighted-average discount rate - operating leases	3.70%		3.70%		4.00%