Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Oct. 20, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Transition Report	false
Entity Central Index Key	0000350698
Entity File Number	1-13107
Entity Registrant Name	AUTONATION, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	73-1105145
Entity Address, Address Line One	200 SW 1st Avenue
Entity Address, City or Town	Fort Lauderdale
Entity Address, State or Province	FL
Entity Address, Postal Zip Code	33301
Amendment Flag	false
City Area Code	954
Local Phone Number	769-6000
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	AN
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		65,538,144