Consolidated Statement of Shareowners' Equity - USD ($) $ in Millions	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss	Common stock in treasury, at cost
Beginning balance at Sep. 30, 2015			$ 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 (2018, $3.51 per share; 2017, $3.04 per share; 2016, $2.90 per share)				(378.2)
Other comprehensive income (loss)	(204.2)				(204.2)
Purchases						(500.4)
Shares delivered under incentive plans						50.3
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 (2018, $3.51 per share; 2017, $3.04 per share; 2016, $2.90 per share)				(390.7)
Other comprehensive income (loss)	359.6				359.6
Purchases						(337.3)
Shares delivered under incentive plans						166.4
Ending balance at Sep. 30, 2017	2,663.6	181.4	1,638.0	6,103.4	(1,179.2)	(4,080.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income tax benefit from share-based compensation			0.0
Share-based compensation expense			37.3
Shares delivered under incentive plans			6.1
Net income	535.5			535.5
Cash dividends (2018, $3.51 per share; 2017, $3.04 per share; 2016, $2.90 per share)				(440.8)
Other comprehensive income (loss)	237.3				237.3
Purchases						(1,500.5)
Shares delivered under incentive plans						79.0
Ending balance at Sep. 30, 2018	$ 1,617.5	$ 181.4	$ 1,681.4	$ 6,198.1	$ (941.9)	$ (5,501.5)