Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net Income (Loss) Attributable to Parent	$ 287.2	$ 189.3
Denominator:
Denominator for basic earnings per share — weighted average common shares	375.1	375.8
Effect of dilutive securities:
Employee stock awards (shares)	5.0	8.0
Denominator for diluted earnings per share — adjusted weighted average common shares	380.1	383.8
Basic net income per common share attributable to Parent (in dollars per share)	$ 0.77	$ 0.50
Diluted net income per common share attributable to Parent (in dollars per share)	$ 0.76	$ 0.49