Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Jun. 30, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 2.2	$ 2.7
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	650,000,000	650,000,000
Common stock, shares issued (in shares)	154,500,000	154,500,000
Common stock, shares outstanding (in shares)	115,700,000	116,300,000
Treasury stock, shares (in shares)	38,800,000	38,100,000