v2.4.0.6

Debt (Details) (USD $)			9 Months Ended			9 Months Ended
	Nov. 30, 2012	Feb. 29, 2012	Nov. 30, 2012 Line Of Credit [Member]	Nov. 30, 2012 Term Securitizations Debt [Member]	Nov. 30, 2012 Warehouse Facilities [Member]	Nov. 30, 2012 Warehouse Facility One [Member] Warehouse Facilities [Member]	Nov. 30, 2012 Warehouse Facility Two [Member] Warehouse Facilities [Member]	Nov. 30, 2012 Maximum [Member] Finance and Capital Lease Obligation [Member]	Nov. 30, 2012 Minimum [Member] Finance and Capital Lease Obligation [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity of credit facility			$ 700,000,000
Revolving credit facility, expiration date			Aug. 01, 2016
Revolving credit facility, amount outstanding			700,000
Initial lease terms								20 years	15 years
Finance and capital lease obligations current	15,885,000	14,108,000
Finance and capital lease obligations noncurrent	341,424,000	353,566,000
Debt maturity, end				Apr. 01, 2019
Non-recourse notes payable	5,380,000,000	4,680,000,000			876,000,000
Current portion of non-recourse notes payable	169,399,000	174,337,000
Warehouse facilities maximum borrowing capacity					1,600,000,000
Remaining borrowing capacity					724,000,000
Amount of facility expiring						$ 800,000,000	$ 800,000,000
Warehouse facility expiration date						Aug. 01, 2013	Feb. 01, 2013

X

- Definition

Amount of facility expiring

+ References

No definition available.

+ Details

Name:	kmx_AmountOfFacilityExpiring
Namespace Prefix:	kmx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

For sale-leasebacks accounted for using the finance method and capital leases, the amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal, through the balance sheet date and due to be paid within one year (or one operating cycle, if longer) of the balance sheet date.

+ References

No definition available.

+ Details

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

X

- Definition

For sale-leasebacks accounted for using the finance method and capital leases, the amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal, through the balance sheet date and due to be paid more than one year (or one operating cycle, if longer) after the balance sheet

+ References

No definition available.

+ Details

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

X

- Definition

Initial lease terms

+ References

No definition available.

+ Details

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

X

- Definition

Current portion of the 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:	kmx_NonRecourseDebtCurrent
Namespace Prefix:	kmx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- 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

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

X

- 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

X

- 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

X

- Details

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

X

- 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

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Data Type:	xbrli:dateItemType
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Period Type:	duration

X

- Definition

Amount borrowed under the credit facility as of the balance sheet date.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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X

- 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

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

X

- 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

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



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

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



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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

X

- 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

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Balance Type:	credit
Period Type:	instant