Share-Based Compensation and Benefit Plans (Employee Stock Purchase Plan) (Narrative) (Details)	12 Months Ended
Dec. 31, 2019
Employee stock purchase plan [Member]
Share-Based Compensation and Benefit Plans
Employee stock purchase plan stock purchase percentage	85.00%

Percent of fair market value of Company's common stock that eligible employees, participating in employee stock purchase plan, may purchase the stock at within the plan.

No definition available.

Name:	orly_EmployeeStockPurchasePlanStockPurchasePercentage
Namespace Prefix:	orly_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration