Fair Value Measurements - Schedule of carrying amounts and estimated fair values of financial instruments not recorded at fair value in the financial statements (Details) - Level 2 - USD ($) $ in Millions	Sep. 30, 2021	Jun. 30, 2021
Carrying Value
Carrying amounts and estimated fair values of financial instruments not recorded at fair value
Long-term debt	$ 694.8	$ 694.5
Company-owned life insurance	25.4	24.6
Fair Value
Carrying amounts and estimated fair values of financial instruments not recorded at fair value
Long-term debt	741.7	754.7
Company-owned life insurance	$ 25.4	$ 24.6