Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Sep. 30, 2017	Oct. 31, 2017	Mar. 31, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	ROCKWELL AUTOMATION INC.
Entity Central Index Key	0001024478
Document Type	10-K
Document Period End Date	Sep. 30, 2017
Amendment Flag	false
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--09-30
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 19.9
Entity Common Stock, Shares Outstanding		128,502,915