Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 30, 2017	Sep. 30, 2017
Statement of Financial Position [Abstract]
Accounts receivable, reserves	$ 11.5	$ 9.8
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	1,623,000	1,623,000
Preferred stock, issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	750,000,000	750,000,000
Common stock, issued (in shares)	288,750,000	287,853,000
Treasury stock (in shares)	12,560,000	12,560,000