Document And Entity Information - shares |
3 Months Ended | |
|---|---|---|
May. 31, 2015 |
Jun. 30, 2015 |
|
| Document And Entity Information [Abstract] | ||
| Document Type | 10-Q | |
| Amendment Flag | false | |
| Document Period End Date | May 31, 2015 | |
| Document Fiscal Year Focus | 2016 | |
| Document Fiscal Period Focus | Q1 | |
| Entity Registrant Name | CARMAX INC | |
| Entity Central Index Key | 0001170010 | |
| Entity Current Reporting Status | Yes | |
| Entity Well-known Seasoned Issuer | Yes | |
| Entity Voluntary Filers | No | |
| Current Fiscal Year End Date | --02-29 | |
| Entity Filer Category | Large Accelerated Filer | |
| Entity Common Stock, Shares Outstanding | 208,041,760 |