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.

No definition available.

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount
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

- Details

Name:	us-gaap_DebtInstrumentAxis=kmx_WarehouseFacilityThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kmx_WarehouseFacilityTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kmx_WarehouseFacilityOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kmx_WarehouseFacilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kmx_TermSecuritizationsDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt (Schedule of Funding Vehicles) (Details) - USD ($) $ in Thousands	Nov. 30, 2020	Feb. 29, 2020
Debt Instrument [Line Items]
Non-Recourse Debt	$ 13,620,332	$ 13,613,272
Warehouse Facility Three
Debt Instrument [Line Items]
Warehouse Facilities Maximum Borrowing Capacity	1,400,000
Warehouse Facility Two
Debt Instrument [Line Items]
Warehouse Facilities Maximum Borrowing Capacity	180,000
Warehouse Facility One
Debt Instrument [Line Items]
Warehouse Facilities Maximum Borrowing Capacity	1,950,000
Warehouse Facilities [Member]
Debt Instrument [Line Items]
Warehouse Facilities Maximum Borrowing Capacity	3,530,000
Debt Instrument, Unused Borrowing Capacity, Amount	1,220,000
Non-Recourse Debt	2,310,000
Term Securitizations Debt [Member]
Debt Instrument [Line Items]
Non-Recourse Debt	$ 11,310,000