Document and Entity Information Document
Sep. 29, 2022
Entity Information [Line Items]  
Document Type 8-K
Document Period End Date Sep. 29, 2022
Entity Registrant Name CARMAX, INC.
Entity Central Index Key 0001170010
Amendment Flag false
Entity Incorporation, State or Country Code VA
Entity File Number 1-31420
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
Written Communications false
Soliciting Material false
Pre-commencement Tender Offer false
Pre-commencement Issuer Tender Offer false
Title of 12(b) Security Common Stock
Trading Symbol KMX
Security Exchange Name NYSE
Entity Emerging Growth Company false