Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net Income (Loss) Attributable to Parent	$ 482.7	$ 351.3	$ 914.0	$ 638.4
Denominator:
Denominator for basic earnings per share — weighted average common shares	365.8	373.3	367.1	374.2
Effect of dilutive securities:
Employee stock awards (shares)	4.3	4.4	4.7	4.7
Denominator for diluted earnings per share — adjusted weighted average common shares	370.1	377.7	371.8	378.9
Basic net income per common share attributable to Parent (in dollars per share)	$ 1.32	$ 0.94	$ 2.49	$ 1.71
Diluted net income per common share attributable to Parent (in dollars per share)	$ 1.30	$ 0.93	$ 2.46	$ 1.68