Fair Value Measurements (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Non-financial assets and liabilities measured at fair value on a nonrecurring basis	$ 0	$ 0

Represents the aggregate of the non-financial assets and/or liabilities reported on the balance sheet at period end measured at fair value on a nonrecurring basis. Non-financial assets and liabilities may include assets acquired in a business combination or property and equipment that are determined to be impaired.

No definition available.

Name:	orly_NonFinancialAssetsAndLiabilitiesFairValueNonrecurring
Namespace Prefix:	orly_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant