Business And Credit Concentrations (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Business And Credit Concentrations [Abstract]
Manufacturer receivables	$ 138.4	$ 159.9

The amount due to the company from manufacturers or distributors, within one year of the balance sheet date, including (1) rebates and assistance for holdbacks, floorplan interest and advertising expenses; (2) incentives based on achieving certain objectives; and (3) amounts due for warranty and service work performed for customers.

No definition available.

Name:	an_ManufacturerReceivables
Namespace Prefix:	an_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant