v3.24.1.u1
Document And Entity Information - USD ($)
12 Months Ended
Feb. 29, 2024
Apr. 11, 2024
Aug. 31, 2023
Entity Information [Line Items]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Feb. 29, 2024    
Document Transition Report false    
Entity File Number 001-31420    
Entity Registrant Name CARMAX, INC.    
Entity Central Index Key 0001170010    
Current Fiscal Year End Date --02-29    
Document Fiscal Year Focus 2024    
Document Fiscal Period Focus FY    
Amendment Flag false    
Entity Incorporation, State or Country Code VA    
Entity Tax Identification Number 54-1821055    
Entity Address, Address Line One 12800 Tuckahoe Creek Parkway    
Entity Address, City or Town Richmond,    
Entity Address, State or Province VA    
Entity Address, Postal Zip Code 23238    
City Area Code 804    
Local Phone Number 747-0422    
Title of 12(b) Security Common Stock    
Trading Symbol KMX    
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    
Entity Shell Company false    
ICFR Auditor Attestation Flag true    
Entity Public Float     $ 12,959,000,271
Entity Common Stock, Shares Outstanding   157,387,560  
Auditor Name KPMG LLP    
Auditor Location Richmond, VA    
Auditor Firm ID 185    
Document Financial Statement Error Correction [Flag] false