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, 2017	$ 7,747.6	$ 3.8	$ 2,992.2	$ 4,946.0	$ (194.9)	$ 0.5
Noncontrolling interests acquired	175.2					175.2
Net income	188.8	0.0	0.0	189.3	0.0	(0.5)
Exercise of stock options	14.8	0.1	14.7
Stock issued under employee incentive plans			0.0
Cash paid for shares withheld for taxes	(10.3)	0.0	10.3	0.0	0.0	0.0
Stock-based compensation expense	13.6		13.6
Cash dividends declared	(47.1)			(47.1)
Repurchases of common stock	(25.4)				(25.4)
Distributions to noncontrolling interests	(1.8)					(1.8)
Ending Balances at Dec. 31, 2017	8,055.4	3.9	3,010.2	5,088.2	(220.3)	173.4
Beginning Balances at Sep. 30, 2017	7,747.6	3.8	2,992.2	4,946.0	(194.9)	0.5
Net income	539.7
Cash paid for shares withheld for taxes	(10.3)
Ending Balances at Mar. 31, 2018	8,371.9	3.9	3,045.7	5,392.1	(242.8)	173.0
Beginning Balances at Dec. 31, 2017	8,055.4	3.9	3,010.2	5,088.2	(220.3)	173.4
Net income	350.8	0.0	0.0	351.0	0.0	(0.2)
Exercise of stock options	16.3	0.0	16.3
Stock issued under employee incentive plans	1.8		1.8
Stock-based compensation expense	17.4		17.4
Cash dividends declared	(47.1)			(47.1)
Repurchases of common stock	(22.5)				(22.5)
Distributions to noncontrolling interests	(0.2)					(0.2)
Ending Balances at Mar. 31, 2018	8,371.9	3.9	3,045.7	5,392.1	(242.8)	173.0
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		0.0
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	(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, 2018	9,158.9	3.9	3,085.0	6,217.9	(322.4)	174.5
Net income	641.1
Cash paid for shares withheld for taxes	(19.5)
Ending Balances at Mar. 31, 2019	9,534.0	3.9	3,123.4	6,771.6	(538.6)	173.7
Beginning Balances at Dec. 31, 2018	9,298.2	3.9	3,107.6	6,476.2	(463.0)	173.5
Net income	354.4	0.0	0.0	351.3	0.0	3.1
Exercise of stock options	11.4	0.0	11.4
Stock issued under employee incentive plans	2.3		2.0			0.3
Cash paid for shares withheld for taxes	(15.4)	0.0	15.4	0.0	0.0	0.0
Stock-based compensation expense	17.8		17.8
Cash dividends declared	(55.9)			(55.9)
Repurchases of common stock	(75.6)				(75.6)
Distributions to noncontrolling interests	(3.2)					3.2
Ending Balances at Mar. 31, 2019	$ 9,534.0	$ 3.9	$ 3,123.4	$ 6,771.6	$ (538.6)	$ 173.7