Consolidated Statement of Shareowners' Equity - USD ($) $ in Millions	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss	Treasury stock
Beginning balance at Sep. 30, 2014			$ 1,512.3	$ 4,839.6	$ (948.0)	$ (2,927.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income tax benefit from share-based compensation			12.4
Share-based compensation expense			40.7
Shares delivered under incentive plans			(13.3)
Net income	$ 827.6			827.6
Cash dividends (2017, $3.04 per share; 2016, $2.90 per share; 2015, $2.60 per share)				(350.1)
Shares delivered under incentive plans				(0.2)		74.6
Other comprehensive income (loss)	(386.6)				(386.6)
Purchases						(606.4)
Ending balance at Sep. 30, 2015	2,256.8	$ 181.4	1,552.1	5,316.9	(1,334.6)	(3,459.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income tax benefit from share-based compensation			3.3
Share-based compensation expense			39.5
Shares delivered under incentive plans			(6.7)
Net income	729.7			729.7
Cash dividends (2017, $3.04 per share; 2016, $2.90 per share; 2015, $2.60 per share)				(378.2)
Shares delivered under incentive plans				0.0		50.3
Other comprehensive income (loss)	(204.2)				(204.2)
Purchases						(500.4)
Ending balance at Sep. 30, 2016	1,990.1	181.4	1,588.2	5,668.4	(1,538.8)	(3,909.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income tax benefit from share-based compensation			0.0
Share-based compensation expense			37.4
Shares delivered under incentive plans			12.4
Net income	825.7			825.7
Cash dividends (2017, $3.04 per share; 2016, $2.90 per share; 2015, $2.60 per share)				(390.7)
Shares delivered under incentive plans				0.0		166.4
Other comprehensive income (loss)	359.6				359.6
Purchases						(337.3)
Ending balance at Sep. 30, 2017	$ 2,663.6	$ 181.4	$ 1,638.0	$ 6,103.4	$ (1,179.2)	$ (4,080.0)