XML 63 R52.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Stock and Stock-Based Incentive Plans Stock and Stock-Based Incentive Plans (Unrecognized Compensation Expense) (Details) $ in Millions | 3 Months Ended
--- | ---
May 31, 2018 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 79.0
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 2 years 6 months
Stock Option |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 55.9
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 2 years 8 months 12 days
Stock-settled market stock units |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 21.0
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 1 year 10 months 24 days
Stock-settled performance stock units |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 2.0
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 1 year 3 months 18 days
Restricted stock awards |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 0.1
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 1 month 6 days
Other share-based incentives |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 2.1
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 1 year 2 months 12 days

X
- Definition Unrecognized cost of unvested share-based compensation awards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=96867065&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 unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=96867065&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=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: |