Document and Entity Information Document	9 Months Ended
	Sep. 30, 2012	Oct. 23, 2012
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2012
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2012
Trading Symbol	AN
Entity Registrant Name	AUTONATION, INC.
Entity Central Index Key	0000350698
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		121,762,984