XML 74 R59.htm IDEA: XBRL DOCUMENT
v3.21.2

Stock and Stock-Based Incentive Plans (Unrecognized Compensation Expense) (Details) $ in Millions | 3 Months Ended
--- | ---
May 31, 2021 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ 98.6
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition | 2 years 3 months 18 days
Equity Option [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ 70.1
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition | 2 years 6 months
Stock-settled market stock units (MSUs) |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ 23.8
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition | 1 year 9 months 18 days
Performance Shares [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ 4.5
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition | 1 year 3 months 18 days
Deferred Stock Units [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ 0.0
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition | 0 days
Restricted Stock [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ 0.2
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition | 1 year 8 months 12 days
Other share-based incentives |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ 4.7
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition | 1 year 3 months 18 days

X
- Definition Amount of cost not yet recognized for nonvested award under share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_StockOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=kmx_StockSettledRestrictedStockUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=kmx_DeferredStockUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=kmx_OthersharebasedincentivesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |