Initial Lease Terms.

No definition available.

Name:	kmx_InitialLeaseTerms
Namespace Prefix:	kmx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under all warehouse facilities without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facilities.

+ References

No definition available.

+ Details

Name:	kmx_WarehouseFacilitiesMaximumBorrowingCapacity
Namespace Prefix:	kmx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of total borrowing capacity currently available under the warehouse facilities (current borrowing capacity less the amount of borrowings outstanding).

+ References

No definition available.

+ Details

Name:	kmx_WarehouseFacilitiesRemainingBorrowingCapacity
Namespace Prefix:	kmx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects when a warehouse facility terminates, which may be presented in a variety of ways (year, month and year, day, month and year, quarter).

+ References

No definition available.

+ Details

Name:	kmx_WarehouseFacilityExpirationDate
Namespace Prefix:	kmx_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

Latest date the outstanding debt instruments are required to be repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentMaturityDateRangeEnd1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of debt for which creditor does not have general recourse to the debtor but rather has recourse only to the property used for collateral in the transaction or other specific property.

+ References

No definition available.

+ Details

Name:	us-gaap_NonRecourseDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Debt (Narrative) (Details) (USD $) In Millions, unless otherwise specified			9 Months Ended		9 Months Ended				9 Months Ended
	Nov. 30, 2013	Feb. 28, 2013	Nov. 30, 2013 Revolving Credit Facility [Member]	Nov. 30, 2013 Warehouse Facilities [Member]	Nov. 30, 2013 Term Securitizations Debt [Member]	Nov. 30, 2013 Warehouse Facility One [Member] Warehouse Facilities [Member]	Nov. 30, 2013 Warehouse Facility Two [Member] Warehouse Facilities [Member]	Nov. 30, 2013 Previously Reported [Member] Warehouse Facility Two [Member] Warehouse Facilities [Member]	Nov. 30, 2013 Minimum [Member] Finance And Capital Lease Obligation [Member]	Nov. 30, 2013 Maximum [Member] Finance And Capital Lease Obligation [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity of credit facility			$ 700
Revolving credit facility, expiration date			Aug. 01, 2016
Initial lease terms, in years									15 years	20 years
Debt maturity, end					Apr. 01, 2020
Non-recourse notes payable	6,970.0	5,860.0		807.0	6,160.0
Warehouse facilities maximum borrowing capacity				1,800		800	1,000	900
Remaining borrowing capacity				$ 993.0
Warehouse facility expiration date						Aug. 01, 2014	Feb. 01, 2014