XML 61 R44.htm IDEA: XBRL DOCUMENT v3.8.0.1

Description of Business and Summary of Significant Accounting Policies (Organization and Business, Inventory) (Details)	12 Months Ended
	Dec. 31, 2017 brand store franchises
Product Information [Line Items]
Owned and operated new vehicle franchises | franchises	360
Number of brands | brand	33
Percentage of new vehicle sales from core brands (percent)	93.00%
Dealerships [Member]
Product Information [Line Items]
Number of stores	253
Collision Centers [Member]
Product Information [Line Items]
Number of stores	76

X

- Definition

The number of new vehicle brands sold by the company's stores.

+ References

No definition available.

+ Details

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

X

- Definition

Represents the number of owned and operated new vehicle franchises.

+ References

No definition available.

+ Details

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

X

- Definition

The percentage of new vehicles sold that represent the core brands of new vehicles sold by the company.

+ References

No definition available.

+ Details

Name:	an_PercentageOfNewVehicleSalesCoreBrands
Namespace Prefix:	an_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- 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

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

X

- Details

Name:	us-gaap_ConsolidatedEntitiesAxis=an_DealershipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_ConsolidatedEntitiesAxis=an_CollisionCentersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: