Leases - Lease cost (Details) $ in Millions	3 Months Ended
	Sep. 30, 2019 USD ($)
Leases [Abstract]
Operating lease cost	$ 3.4
Short-term lease cost	0.8
Variable lease cost	0.1
Total lease cost	4.3
Operating cash flow payments from operating leases	3.3
Non-cash ROU assets obtained in exchange for lease obligations	$ 0.9
Weighted-average remaining lease term - operating leases	8 years 6 months
Weighted-average discount rate - operating leases	3.80%