Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2021	Feb. 15, 2022	Jun. 30, 2021
Document And Entity Information [Abstract]
Document Annual Report	true
Document Type	10-K
Document Period End Date	Dec. 31, 2021
Document Fiscal Period Focus	FY
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 Ave
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 4.5
Entity Common Stock, Shares Outstanding		61,671,559
Documents Incorporated by Reference	Portions of the registrant’s Proxy Statement relating to its 2022 Annual Meeting of Stockholders to be filed with the SEC within 120 days after the end of the fiscal year ended December 31, 2021 are incorporated herein by reference in Part III.
Auditor Name	KPMG LLP
Auditor Location	Fort Lauderdale, FL
Auditor Firm ID	185