Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2021
Operating loss carryforwards disclosures
Deferred income taxes	$ (0.4)	$ (3.1)	$ (33.6)
Deferred tax assets, operating loss carryforwards, subject to expiration	227.8
Amount of future tax benefits	6.9
Increase (decrease) in valuation allowance	(7.7)
United Kingdom
Operating loss carryforwards disclosures
Deferred tax assets, operating loss carryforwards, not subject to expiration	10.0
Deferred income taxes	2.8
Operating Loss Carryforward, Expired
Operating loss carryforwards disclosures
Increase (decrease) in valuation allowance	(4.5)
Operating Losses, Jurisdictions Without Tax Benefits, Written Off
Operating loss carryforwards disclosures
Increase (decrease) in valuation allowance	(1.7)
Operating loss carryforward, income tax benefit	0.0
Law Changes
Operating loss carryforwards disclosures
Increase (decrease) in valuation allowance	(2.2)
Projected Future Taxable Income
Operating loss carryforwards disclosures
Increase (decrease) in valuation allowance	(0.9)
Operating Losses, Jurisdictions Without Tax Benefits
Operating loss carryforwards disclosures
Increase (decrease) in valuation allowance	1.6
Operating loss carryforward, income tax benefit	$ 0.0