Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 01, 2021
Cover [Abstract]
Entity Registrant Name	OLD DOMINION FREIGHT LINE, INC.
Entity Central Index Key	0000878927
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Trading Symbol	ODFL
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		115,011,172
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	0-19582
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	56-0751714
Entity Address, Postal Zip Code	27360
Entity Address, Address Line One	500 Old Dominion Way
Entity Address, City or Town	Thomasville
Entity Address, State or Province	NC
City Area Code	336
Local Phone Number	889-5000
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock ($0.10 par value)
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false