Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Feb. 24, 2014	Jun. 30, 2013
Document and Entity Information
Document type	10-K
Amendment flag	false
Document period end date	Dec. 31, 2013
Document fiscal year focus	2013
Current fiscal year end date	--12-31
Document fiscal period focus	FY
Entity registrant name	O REILLY AUTOMOTIVE INC
Trading symbol	orly
Entity central index key	0000898173
Entity well-known seasoned issuer	Yes
Entity voluntary filers	No
Entity current reporting status	Yes
Entity filer category	Large Accelerated Filer
Entity common stock, shares outstanding		106,364,924	108,886,775
Entity public float		$ 16,366,370,856	$ 12,262,828,601