v2.4.0.6

Comprehensive Income (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Nov. 30, 2011	Feb. 28, 2011
Comprehensive Income [Abstract]
Deferred taxes	$ 10.1	$ 10.7

X

- Definition

The balance of deferred taxes on items remaining in accumulated other comprehensive income loss

+ References

No definition available.

+ Details

Name:	kmx_AccumulatedOtherComprehensiveIncomeLossDeferredTaxes
Namespace Prefix:	kmx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_ComprehensiveIncomeNetOfTaxAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration