Consolidated Statement of Shareowners' Equity - USD ($) $ in Millions		Total	Cumulative Effect, Period of Adoption, Adjustment	Common stock	Additional paid-in capital	Retained earnings	Retained earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive loss	Accumulated other comprehensive loss Cumulative Effect, Period of Adoption, Adjustment	Common stock in treasury, at cost	Total attributable to Rockwell Automation, Inc.	Total attributable to Rockwell Automation, Inc. Cumulative Effect, Period of Adoption, Adjustment	Noncontrolling interests
Balance at beginning of period at Sep. 30, 2019		$ 404.2	$ 2.2	$ 181.4	$ 1,709.1	$ 6,440.2	$ 149.0	$ (1,488.0)	$ (146.8)	$ (6,438.5)	$ 404.2	$ 2.2	$ 0.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		315.4				310.7					310.7		4.7
Other comprehensive income (loss)		47.0						46.7			46.7		0.3
Common stock issued (including share-based compensation impact)		117.4			16.3					101.1	117.4
Share repurchases		(100.2)								(100.2)	(100.2)
Cash dividends declared	[1]	(117.9)				(117.9)					(117.9)
Change in noncontrolling interest		368.4			50.1			3.8			53.9		314.5
Balance at end of period at Dec. 31, 2019		1,036.5		181.4	1,775.5	6,782.0		(1,584.3)	$ (143.0)	(6,437.6)	717.0		319.5
Balance at beginning of period at Sep. 30, 2020		1,346.8		181.4	1,830.7	7,139.8		(1,614.2)		(6,509.9)	1,027.8		319.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		590.4				593.3					593.3		(2.9)
Other comprehensive income (loss)		87.0						86.9			86.9		0.1
Common stock issued (including share-based compensation impact)		61.6			25.6					36.0	61.6
Share repurchases		(87.7)								(87.7)	(87.7)
Cash dividends declared	[1]	(124.3)				(124.3)					(124.3)
Balance at end of period at Dec. 31, 2020		$ 1,873.8		$ 181.4	$ 1,856.3	$ 7,608.8		$ (1,527.3)		$ (6,561.6)	$ 1,557.6		$ 316.2

[1] Cash dividends were $1.07 per share and $1.02 per share in the periods ending December 31, 2020 and 2019, respectively.