CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Sep. 30, 2016	[1]
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ (42.2)	$ (24.2)
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	1,000,000.0	1,000,000.0
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	189,000,000	189,000,000.0
Common stock, shares issued (in shares)	91,700,000	93,700,000
Common stock, shares outstanding (in shares)	91,700,000	93,700,000

[1] The condensed consolidated balance sheet as of September 30, 2016 was derived from audited financial statements as of that date, but does not include all disclosures required by accounting principles generally accepted in the United States of America.