Document and Entity Information - shares	3 Months Ended
	Dec. 31, 2017	Jan. 22, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	ROCKWELL COLLINS INC
Entity Central Index Key	0001137411
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Entity Registrant Name	10-Q
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		163,942,914