Interim Financial Statements (Details)	9 Months Ended
Sep. 30, 2013 franchises brand stores
Interim Financial Statements [Abstract]
Owned and operated new vehicle franchises	267
Number of stores	226
Number of brands	33
Percentage of new vehicle sales core brands	95.00%

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

No definition available.

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