Name:	an_CreditSpreadImpactLeverageRatioCreditAgreement
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The minimum, inclusive, leverage ratio, as defined in the credit agreement, in which the credit spread on the revolver would increase based on the pricing terms outlined in the agreement.

No definition available.

Name:	an_DebtCovenantIncreaseinLeverageRatioMinimumBenchmarkRange
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The maximum, exclusive, leverage ratio, as defined in the credit agreement, in which the current credit spread on the revolver applies based on pricing terms outlined in the credit agreement.

No definition available.

Name:	an_DebtCovenantMaximumExclusiveRangeLeverageRatioCreditSpread
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Data Type:	xbrli:pureItemType
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The minimum, inclusive, leverage ratio, as defined in the credit agreement, in which the current credit spread on the revolver applies based on pricing terms outlined in the agreement.

No definition available.

Name:	an_DebtCovenantMinimumInclusiveRangeLeverageRatioCreditSpread
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The maximum leverage ratio required under the company's credit agreement, which is a contractually defined amount principally reflecting non-vehicle debt divided by a contractually defined measure of earnings with certain adjustments.

No definition available.

Name:	an_DebtInstrumentCovenantTermsMaximumLeverageRatio
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The public offering price of senior notes as a percentage of the aggregate principal amount.

No definition available.

Name:	an_DebtInstrumentPercentageAggregateOfferingPricePercentage
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Maximum amount of increase in the revolving credit facility allowed under the accordion feature of the credit agreement, subject to credit availability and certain other conditions.

No definition available.

Name:	an_LineofCreditFacilityAdditionalBorrowingCapacity
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of current borrowing capacity under the revolving credit facility considering any current restrictions on the amount that could be borrowed and any amounts currently outstanding under the facility.

No definition available.

Name:	an_LineofCreditRestrictedBorrowingCapacity
Namespace Prefix:	an_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The maximum amount of letters of credit that can be issued under the terms of the revolving credit facilities.

No definition available.

Name:	an_RevolvingCreditFacilitiesLetterOfCreditSublimit
Namespace Prefix:	an_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
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Data Type:	num:percentItemType
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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_DebtInstrumentCarryingAmount
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Contractual interest rate for funds borrowed, under the debt agreement.

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
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Data Type:	num:percentItemType
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Period Type:	instant

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.

No definition available.

Name:	us-gaap_DebtInstrumentLineItems
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Period Type:	duration

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

Name:	us-gaap_LettersOfCreditOutstandingAmount
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

No definition available.

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
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Name:	us-gaap_DebtInstrumentAxis=an_SeniorNotesatThreePointFivePercentDue2024Member
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Name:	us-gaap_DebtInstrumentAxis=an_SeniorNotesatThreePointEightPercentDue2027Member
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Name:	us-gaap_DebtInstrumentAxis=an_SeniorNotesatSixPointSevenFivePercentdue2018Member
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Name:	us-gaap_DebtInstrumentAxis=an_SeniorNotesatFourPointFivePercentDue2025Member
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Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
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