Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net Income (Loss) Attributable to Parent	$ 929.5	$ 482.7	$ 1,721.3	$ 914.0
Denominator:
Denominator for basic earnings per share — weighted average common shares	362.3	365.8	363.4	367.1
Effect of dilutive securities:
Employee stock awards (shares)	4.9	4.3	5.2	4.7
Denominator for diluted earnings per share — adjusted weighted average common shares	367.2	370.1	368.6	371.8
Basic net income per common share attributable to Parent (in dollars per share)	$ 2.57	$ 1.32	$ 4.74	$ 2.49
Diluted net income per common share attributable to Parent (in dollars per share)	$ 2.53	$ 1.30	$ 4.67	$ 2.46