Document and Entity Information	6 Months Ended
	Mar. 31, 2019 shares
Document and Entity Information [Abstract]
Entity Registrant Name	ROCKWELL AUTOMATION INC.
Entity Central Index Key	0001024478
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Emerging Growth	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding (in shares)	118,362,039