Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Jun. 30, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 3.7	$ 2.3
Preferred stock, shares authorized (in shares)	25,000,000.0	25,000,000.0
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)	116,500,000	118,300,000
Treasury stock, shares (in shares)	38,000,000	36,200,000