The number of collective-bargaining agreements that require contributions to multiemployer pension plans.

No definition available.

Name:	an_MultiemployerPlansCollectiveBargainingArrangementNumberOfAgreements
Namespace Prefix:	an_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of collective-bargaining agreements that expired on a specific date, but are currently extended during collective bargaining for new agreements.

+ References

No definition available.

+ Details

Name:	an_MultiemployerPlansCollectiveBargainingArrangementNumberOfAgreementsExpiredinPeriod
Namespace Prefix:	an_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation 12B

-Number 240

-Section 12b

-Subsection 1

+ Details

Name:	dei_EntityTaxIdentificationNumber
Namespace Prefix:	dei_
Data Type:	dei:nineDigitItemType
Balance Type:	na
Period Type:	duration

- Definition

Three digit plan number for a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlanNumber
Namespace Prefix:	us-gaap_
Data Type:	us-types:threeDigitItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of contributions made to multiemployer plans by the employer. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450702-114947

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450691-114947

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (e)(1)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlanPeriodContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Indicate the multiemployer plan's certified zone status as currently required by the Pension Protection Act of 2006 or a subsequent amendment thereof. The zone status categories are red (critical status), orange (seriously endangered), yellow (endangered), and green (none of the above). The acceptable values are "red", "orange", "yellow", "green", "other", and "NA". A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlansCertifiedZoneStatus
Namespace Prefix:	us-gaap_
Data Type:	us-types:zoneStatusItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

Indicate whether the employer paid a surcharge to the pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. The acceptable values are "no", "yes", and "NA".

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (f)(2)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlansSurcharge
Namespace Prefix:	us-gaap_
Data Type:	us-types:surchargeItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of stores.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfStores
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_MultiemployerPlanNameAxis=an_AutomotiveIndustriesPensionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MultiemployerPlanNameAxis=us-gaap_MultiemployerPlanIndividuallyInsignificantMultiemployerPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=us-gaap_MultiemployerPlansPensionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Multiemployer Pension Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 agreements	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2011 agreements	May 31, 2011 agreements
Multiemployer Plans [Line Items]
Number of stores	232us-gaap_NumberOfStores
Contributions of AutoNation	$ 1.1	$ 1.1	$ 0.9
Automotive Industries Pension Plan [Member]
Multiemployer Plans [Line Items]
EIN	941133245
Multiemployer plan number	001
Pension protection act zone status	Red	Red
Contributions of AutoNation	0.8	0.7	0.6
Surcharge imposed	No
Number of collective-bargaining arrangements that require contributions to the Plan	2
Number of collective-bargaining arrangements expired, but currently extended				1	1
Other funds [Member]
Multiemployer Plans [Line Items]
Contributions of AutoNation	$ 0.3	$ 0.4	$ 0.3
Multiemployer Plans, Pension [Member]
Multiemployer Plans [Line Items]
Number of stores	5