Consolidated Statements of Total Equity Consolidated Statements of Total Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Beginning Balances at Sep. 30, 2018	$ 9,158.9	$ 3.9	$ 3,085.0	$ 6,217.9	$ (322.4)	$ 174.5
Cumulative effect of adoption of ASC 606	27.1			27.1
Net income	286.7	0.0	0.0	287.2	0.0	(0.5)
Exercise of stock options	8.6	0.0	8.6
Stock issued under employee incentive plans			0.0
Cash paid for shares withheld for taxes	(4.1)	0.0	4.1	0.0	0.0	0.0
Stock-based compensation expense	18.1		18.1
Cash dividends declared ($0.175 per share)	(56.0)			(56.0)
Repurchases of common stock	(140.6)				(140.6)
Distributions to noncontrolling interests	(0.5)					(0.5)
Ending Balances at Dec. 31, 2018	9,298.2	3.9	3,107.6	6,476.2	(463.0)	173.5
Beginning Balances at Sep. 30, 2019	10,295.1	3.9	3,179.1	7,640.1	(802.2)	274.2
Net income	432.5	0.0	0.0	431.3	0.0	1.2
Exercise of stock options	4.1	0.0	4.1
Stock issued under employee incentive plans			0.0
Cash paid for shares withheld for taxes	(17.3)	0.0	17.3	0.0	0.0	0.0
Stock-based compensation expense	16.6		16.6
Cash dividends declared ($0.175 per share)	(64.6)			(64.6)
Repurchases of common stock	(163.1)				(163.1)
Distributions to noncontrolling interests	(0.4)					0.4
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Issuance of Equity by Subsidiary to Noncontrolling Interests	0.0		(0.5)			0.5
Ending Balances at Dec. 31, 2019	$ 10,502.9	$ 3.9	$ 3,182.0	$ 8,006.8	$ (965.3)	$ 275.5