Accounting Policies (Policy)	9 Months Ended
Nov. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation and Use of Estimates. The accompanying interim unaudited consolidated financial statements include the accounts of CarMax and our wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. These consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, such interim consolidated financial statements reflect all normal recurring adjustments considered necessary to present fairly the financial position and the results of operations and cash flows for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results to be expected for the full fiscal year. These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and footnotes included in our Annual Report on Form 10-K for the fiscal year ended February 29, 2016.
Use Of Estimates	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates. Certain prior year amounts have been reclassified to conform to the current year’s presentation. Amounts and percentages may not total due to rounding.
Cash And Cash Equivalents	Cash and Cash Equivalents. Cash equivalents of approximately $272,000 as of November 30, 2016, and $109,000 as of February 29, 2016, consisted of highly liquid investments with original maturities of three months or less.
Restricted Cash from Collections on Auto Loan Receivables	Restricted Cash from Collections on Auto Loan Receivables. Cash equivalents totaling $357.0 million as of November 30, 2016, and $343.8 million as of February 29, 2016, consisted of collections of principal, interest and fee payments on securitized auto loan receivables that are restricted for payment to the securitization investors pursuant to the applicable securitization agreements.
Securitizations	Securitizations. We maintain a revolving securitization program composed of three warehouse facilities (“warehouse facilities”) that we use to fund auto loan receivables originated by CAF. We typically elect to fund these receivables through a term securitization or alternative funding arrangement at a later date. We sell the auto loan receivables to one of three wholly owned, bankruptcy-remote, special purpose entities that transfer an undivided percentage ownership interest in the receivables, but not the receivables themselves, to entities formed by third-party investors. These entities issue asset-backed commercial paper or utilize other funding sources supported by the transferred receivables, and the proceeds are used to finance the securitized receivables. We typically use term securitizations to provide long-term funding for most of the auto loan receivables initially securitized through the warehouse facilities. In these transactions, a pool of auto loan receivables is sold to a bankruptcy-remote, special purpose entity that, in turn, transfers the receivables to a special purpose securitization trust. The securitization trust issues asset-backed securities, secured or otherwise supported by the transferred receivables, and the proceeds from the sale of the asset-backed securities are used to finance the securitized receivables. We are required to evaluate term securitization trusts for consolidation. In our capacity as servicer, we have the power to direct the activities of the trusts that most significantly impact the economic performance of the trusts. In addition, we have the obligation to absorb losses (subject to limitations) and the rights to receive any returns of the trusts, which could be significant. Accordingly, we are the primary beneficiary of the trusts and are required to consolidate them. We recognize transfers of auto loan receivables into the warehouse facilities and term securitizations (“securitization vehicles”) as secured borrowings, which result in recording the auto loan receivables and the related non-recourse notes payable on our consolidated balance sheets. The securitized receivables can only be used as collateral to settle obligations of the securitization vehicles. The securitization vehicles and investors have no recourse to our assets beyond the securitized receivables, the amounts on deposit in reserve accounts and the restricted cash from collections on auto loan receivables. We have not provided financial or other support to the securitization vehicles that was not previously contractually required, and there are no additional arrangements, guarantees or other commitments that could require us to provide financial support to the securitization vehicles. See Notes 4 and 10 for additional information on auto loan receivables and non-recourse notes payable.
Auto Loan Receivables, Net	Auto Loan Receivables, Net. Auto loan receivables include amounts due from customers related to retail vehicle sales financed through CAF. The receivables are presented net of an allowance for estimated loan losses. The allowance for loan losses represents an estimate of the amount of net losses inherent in our portfolio of managed receivables as of the applicable reporting date and anticipated to occur during the following 12 months. The allowance is primarily based on the credit quality of the underlying receivables, historical loss trends and forecasted forward loss curves. We also take into account recent trends in delinquencies and defaults, recovery rates and the economic environment. The provision for loan losses is the periodic expense of maintaining an adequate allowance. An account is considered delinquent when the related customer fails to make a substantial portion of a scheduled payment on or before the due date. In general, accounts are charged-off on the last business day of the month during which the earliest of the following occurs: the receivable is 120 days or more delinquent as of the last business day of the month, the related vehicle is repossessed and liquidated, or the receivable is otherwise deemed uncollectible. For purposes of determining impairment, auto loans are evaluated collectively, as they represent a large group of smaller-balance homogeneous loans, and therefore, are not individually evaluated for impairment. See Note 4 for additional information on auto loan receivables. Interest income and expenses related to auto loans are included in CAF income. Interest income on auto loan receivables is recognized when earned based on contractual loan terms. All loans continue to accrue interest until repayment or charge-off. Direct costs associated with loan originations are not considered material, and thus, are expensed as incurred. See Note 3 for additional information on CAF income.
Property And Equipment	Property and Equipment. Property and equipment is stated at cost less accumulated depreciation and amortization of $1.01 billion and $925.3 million as of November 30, 2016 and February 29, 2016, respectively.
Other Assets	Other Assets. Other assets includes amounts classified as restricted cash on deposit in reserve accounts and restricted investments. The restricted cash on deposit in reserve accounts is for the benefit of holders of non-recourse notes payable, and these funds are not expected to be available to the company or its creditors. In the event that the cash generated by the securitized receivables in a given period was insufficient to pay the interest, principal and other required payments, the balances on deposit in the reserve accounts would be used to pay those amounts. Restricted cash on deposit in reserve accounts is invested in money market securities and was $50.2 million as of November 30, 2016, and $46.6 million as of February 29, 2016. Restricted investments includes money market securities primarily held to satisfy certain insurance program requirements, as well as mutual funds held in a rabbi trust established to fund informally our executive deferred compensation plan. Restricted investments totaled $70.7 million as of November 30, 2016, and $63.0 million as of February 29, 2016.
Revenue Recognition	Revenue Recognition. We recognize revenue when the earnings process is complete, generally either at the time of sale to a customer or upon delivery to a customer. As part of our customer service strategy, we guarantee the retail vehicles we sell with a 5-day, money-back guarantee. We record a reserve for estimated returns based on historical experience and trends. We also sell ESP and GAP products on behalf of unrelated third parties, who are the primary obligors, to customers who purchase a vehicle. The ESPs we currently offer on all used vehicles provide coverage up to 60 months (subject to mileage limitations), while GAP covers the customer for the term of their finance contract. We recognize revenue at the time of sale, net of a reserve for estimated contract cancellations. Periodically, we may receive additional revenue based upon the level of underwriting profits of the third parties who administer the products. These additional amounts are recognized as revenue when received. The reserve for cancellations is evaluated for each product, and is based on forecasted forward cancellation curves utilizing historical experience, recent trends and credit mix of the customer base. Our risk related to contract cancellations is limited to the revenue that we receive. Cancellations fluctuate depending on the volume of EPP sales, customer financing default or prepayment rates, and shifts in customer behavior, including those related to changes in the coverage or term of the product. The current portion of estimated cancellation reserves is recognized as a component of accrued expenses and other current liabilities with the remaining amount recognized in other liabilities. See Note 7 for additional information on cancellation reserves. Customers applying for financing who are not approved or are conditionally approved by CAF are generally evaluated by other third-party finance providers. These providers generally either pay us or are paid a fixed, pre-negotiated fee per contract. We recognize these fees at the time of sale. We collect sales taxes and other taxes from customers on behalf of governmental authorities at the time of sale. These taxes are accounted for on a net basis and are not included in net sales and operating revenues or cost of sales.
Derivative Instruments And Hedging Activities	Derivative Instruments and Hedging Activities. We enter into derivative instruments to manage certain risks arising from both our business operations and economic conditions that result in the future known receipt or payment of uncertain cash amounts, the values of which are impacted by interest rates. We recognize the derivatives at fair value as either current assets or current liabilities on the consolidated balance sheets, and where applicable, such contracts covered by master netting agreements are reported net. Gross positive fair values are netted with gross negative fair values by counterparty. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether we have elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. We may enter into derivative contracts that are intended to economically hedge certain risks, even though hedge accounting may not apply or we do not elect to apply hedge accounting. See Note 5 for additional information on derivative instruments and hedging activities.
Recent Accounting Pronouncements	Recent Accounting Pronouncements. Effective in Future Periods. In October 2016, the Financial Accounting Standards Board (“FASB”) issued an accounting pronouncement (FASB ASU 2016-16) related to the income tax effects of intra-entity transfers of assets other than inventory. The pronouncement requires that entities recognize the income tax effects of intra-entity transfers of assets other than inventory when the transfer occurs. Current GAAP prohibits the recognition of those tax effects until the asset has been sold to an outside party. The pronouncement is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. We plan to adopt this pronouncement for our fiscal year beginning March 1, 2018, and are currently evaluating the effect on our consolidated financial statements. In November 2016, the FASB issued an accounting pronouncement (FASB ASU 2016-18) related to the presentation of restricted cash in the statement of cash flows. The pronouncement requires that a statement of cash flows explain the change during the period in cash, cash equivalents, and amounts generally described as restricted cash. Amounts generally described as restricted cash should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The pronouncement is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. We plan to adopt this pronouncement for our fiscal year beginning March 1, 2018, and the pronouncement will result in changes to our consolidated statements of cash flows such that restricted cash amounts will be included in the beginning-of-period and end-of-period cash and cash equivalents totals.

Accounting Policies (Policy)

9 Months Ended

Nov. 30, 2016

Basis of Presentation and Use of Estimates. The accompanying interim unaudited consolidated financial statements include the accounts of CarMax and our wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. These consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, such interim consolidated financial statements reflect all normal recurring adjustments considered necessary to present fairly the financial position and the results of operations and cash flows for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results to be expected for the full fiscal year. These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and footnotes included in our Annual Report on Form 10-K for the fiscal year ended February 29, 2016.

Use Of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates. Certain prior year amounts have been reclassified to conform to the current year’s presentation. Amounts and percentages may not total due to rounding.

Cash And Cash Equivalents

Cash and Cash Equivalents. Cash equivalents of approximately $272,000 as of November 30, 2016, and $109,000 as of February 29, 2016, consisted of highly liquid investments with original maturities of three months or less.

Restricted Cash from Collections on Auto Loan Receivables

Restricted Cash from Collections on Auto Loan Receivables. Cash equivalents totaling $357.0 million as of November 30, 2016, and $343.8 million as of February 29, 2016, consisted of collections of principal, interest and fee payments on securitized auto loan receivables that are restricted for payment to the securitization investors pursuant to the applicable securitization agreements.

Securitizations

Securitizations. We maintain a revolving securitization program composed of three warehouse facilities (“warehouse facilities”) that we use to fund auto loan receivables originated by CAF. We typically elect to fund these receivables through a term securitization or alternative funding arrangement at a later date. We sell the auto loan receivables to one of three wholly owned, bankruptcy-remote, special purpose entities that transfer an undivided percentage ownership interest in the receivables, but not the receivables themselves, to entities formed by third-party investors. These entities issue asset-backed commercial paper or utilize other funding sources supported by the transferred receivables, and the proceeds are used to finance the securitized receivables.

We typically use term securitizations to provide long-term funding for most of the auto loan receivables initially securitized through the warehouse facilities. In these transactions, a pool of auto loan receivables is sold to a bankruptcy-remote, special purpose entity that, in turn, transfers the receivables to a special purpose securitization trust. The securitization trust issues asset-backed securities, secured or otherwise supported by the transferred receivables, and the proceeds from the sale of the asset-backed securities are used to finance the securitized receivables.

We are required to evaluate term securitization trusts for consolidation. In our capacity as servicer, we have the power to direct the activities of the trusts that most significantly impact the economic performance of the trusts. In addition, we have the obligation to absorb losses (subject to limitations) and the rights to receive any returns of the trusts, which could be significant. Accordingly, we are the primary beneficiary of the trusts and are required to consolidate them.

We recognize transfers of auto loan receivables into the warehouse facilities and term securitizations (“securitization vehicles”) as secured borrowings, which result in recording the auto loan receivables and the related non-recourse notes payable on our consolidated balance sheets.

The securitized receivables can only be used as collateral to settle obligations of the securitization vehicles. The securitization vehicles and investors have no recourse to our assets beyond the securitized receivables, the amounts on deposit in reserve accounts and the restricted cash from collections on auto loan receivables. We have not provided financial or other support to the securitization vehicles that was not previously contractually required, and there are no additional arrangements, guarantees or other commitments that could require us to provide financial support to the securitization vehicles.

See Notes 4 and 10 for additional information on auto loan receivables and non-recourse notes payable.

Auto Loan Receivables, Net

Auto Loan Receivables, Net. Auto loan receivables include amounts due from customers related to retail vehicle sales financed through CAF. The receivables are presented net of an allowance for estimated loan losses. The allowance for loan losses represents an estimate of the amount of net losses inherent in our portfolio of managed receivables as of the applicable reporting date and anticipated to occur during the following 12 months. The allowance is primarily based on the credit quality of the underlying receivables, historical loss trends and forecasted forward loss curves. We also take into account recent trends in delinquencies and defaults, recovery rates and the economic environment. The provision for loan losses is the periodic expense of maintaining an adequate allowance.

An account is considered delinquent when the related customer fails to make a substantial portion of a scheduled payment on or before the due date. In general, accounts are charged-off on the last business day of the month during which the earliest of the following occurs: the receivable is 120 days or more delinquent as of the last business day of the month, the related vehicle is repossessed and liquidated, or the receivable is otherwise deemed uncollectible. For purposes of determining impairment, auto loans are evaluated collectively, as they represent a large group of smaller-balance homogeneous loans, and therefore, are not individually evaluated for impairment. See Note 4 for additional information on auto loan receivables.

Interest income and expenses related to auto loans are included in CAF income. Interest income on auto loan receivables is recognized when earned based on contractual loan terms. All loans continue to accrue interest until repayment or charge-off. Direct costs associated with loan originations are not considered material, and thus, are expensed as incurred. See Note 3 for additional information on CAF income.

Property And Equipment

Property and Equipment. Property and equipment is stated at cost less accumulated depreciation and amortization of $1.01 billion and $925.3 million as of November 30, 2016 and February 29, 2016, respectively.

Other Assets

Other Assets. Other assets includes amounts classified as restricted cash on deposit in reserve accounts and restricted investments. The restricted cash on deposit in reserve accounts is for the benefit of holders of non-recourse notes payable, and these funds are not expected to be available to the company or its creditors. In the event that the cash generated by the securitized receivables in a given period was insufficient to pay the interest, principal and other required payments, the balances on deposit in the reserve accounts would be used to pay those amounts. Restricted cash on deposit in reserve accounts is invested in money market securities and was $50.2 million as of November 30, 2016, and $46.6 million as of February 29, 2016.

Restricted investments includes money market securities primarily held to satisfy certain insurance program requirements, as well as mutual funds held in a rabbi trust established to fund informally our executive deferred compensation plan. Restricted investments totaled $70.7 million as of November 30, 2016, and $63.0 million as of February 29, 2016.

Revenue Recognition

Revenue Recognition. We recognize revenue when the earnings process is complete, generally either at the time of sale to a customer or upon delivery to a customer. As part of our customer service strategy, we guarantee the retail vehicles we sell with a 5-day, money-back guarantee. We record a reserve for estimated returns based on historical experience and trends.

We also sell ESP and GAP products on behalf of unrelated third parties, who are the primary obligors, to customers who purchase a vehicle. The ESPs we currently offer on all used vehicles provide coverage up to 60 months (subject to mileage limitations), while GAP covers the customer for the term of their finance contract. We recognize revenue at the time of sale, net of a reserve for estimated contract cancellations. Periodically, we may receive additional revenue based upon the level of underwriting profits of the third parties who administer the products. These additional amounts are recognized as revenue when received. The reserve for cancellations is evaluated for each product, and is based on forecasted forward cancellation curves utilizing historical experience, recent trends and credit mix of the customer base. Our risk related to contract cancellations is limited to the revenue that we receive. Cancellations fluctuate depending on the volume of EPP sales, customer financing default or prepayment rates, and shifts in customer behavior, including those related to changes in the coverage or term of the product. The current portion of estimated cancellation reserves is recognized as a component of accrued expenses and other current liabilities with the remaining amount recognized in other liabilities. See Note 7 for additional information on cancellation reserves.

Customers applying for financing who are not approved or are conditionally approved by CAF are generally evaluated by other third-party finance providers. These providers generally either pay us or are paid a fixed, pre-negotiated fee per contract. We recognize these fees at the time of sale.

We collect sales taxes and other taxes from customers on behalf of governmental authorities at the time of sale. These taxes are accounted for on a net basis and are not included in net sales and operating revenues or cost of sales.

Derivative Instruments And Hedging Activities

Derivative Instruments and Hedging Activities. We enter into derivative instruments to manage certain risks arising from both our business operations and economic conditions that result in the future known receipt or payment of uncertain cash amounts, the values of which are impacted by interest rates. We recognize the derivatives at fair value as either current assets or current liabilities on the consolidated balance sheets, and where applicable, such contracts covered by master netting agreements are reported net. Gross positive fair values are netted with gross negative fair values by counterparty. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether we have elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. We may enter into derivative contracts that are intended to economically hedge certain risks, even though hedge accounting may not apply or we do not elect to apply hedge accounting. See Note 5 for additional information on derivative instruments and hedging activities.

Recent Accounting Pronouncements

Recent Accounting Pronouncements.

Effective in Future Periods. In October 2016, the Financial Accounting Standards Board (“FASB”) issued an accounting pronouncement (FASB ASU 2016-16) related to the income tax effects of intra-entity transfers of assets other than inventory. The pronouncement requires that entities recognize the income tax effects of intra-entity transfers of assets other than inventory when the transfer occurs. Current GAAP prohibits the recognition of those tax effects until the asset has been sold to an outside party. The pronouncement is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. We plan to adopt this pronouncement for our fiscal year beginning March 1, 2018, and are currently evaluating the effect on our consolidated financial statements.

In November 2016, the FASB issued an accounting pronouncement (FASB ASU 2016-18) related to the presentation of restricted cash in the statement of cash flows. The pronouncement requires that a statement of cash flows explain the change during the period in cash, cash equivalents, and amounts generally described as restricted cash. Amounts generally described as restricted cash should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The pronouncement is effective for fiscal years, and for interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted. We plan to adopt this pronouncement for our fiscal year beginning March 1, 2018, and the pronouncement will result in changes to our consolidated statements of cash flows such that restricted cash amounts will be included in the beginning-of-period and end-of-period cash and cash equivalents totals.