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	Dec. 31, 2020	Jun. 30, 2020
Carrying Value
Carrying amounts and estimated fair values of financial instruments not recorded at fair value
Long-term debt	$ 694.0	$ 551.8
Company-owned life insurance	21.7	18.9
Fair Value
Carrying amounts and estimated fair values of financial instruments not recorded at fair value
Long-term debt	754.9	551.1
Company-owned life insurance	$ 21.7	$ 18.9