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, 2015	Jun. 30, 2015
Carrying Value
Carrying amounts and estimated fair values of financial instruments not recorded at fair value
Long-term debt	$ 608.4	$ 607.1
Company-owned life insurance	13.0	13.0
Fair Value
Carrying amounts and estimated fair values of financial instruments not recorded at fair value
Long-term debt	598.4	628.6
Company-owned life insurance	$ 13.0	$ 13.0