Document And Entity Information - shares	3 Months Ended
	May 31, 2025	Jan. 03, 2025
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	May 31, 2025
Document Transition Report	false
Entity File Number	1-31420
Entity Registrant Name	CARMAX, INC.
Entity Central Index Key	0001170010
Current Fiscal Year End Date	--02-28
Document Fiscal Year Focus	2026
Document Fiscal Period Focus	Q1
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 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		150,072,152