Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 21, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Trading Symbol	ODFL
Entity Registrant Name	OLD DOMINION FREIGHT LINE, INC.
Entity Central Index Key	0000878927
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		114,863,803
Entity Public Float			$ 24,053,489,079
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	Yes
ICFR Auditor Attestation Flag	true
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock ($0.10 par value)
Security Exchange Name	NASDAQ
Entity File Number	0-19582
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	56-0751714
Entity Address, Address Line One	500 Old Dominion Way
Entity Address, City or Town	Thomasville
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27360
City Area Code	336
Local Phone Number	889-5000
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	Certain portions of the Company’s Proxy Statement for the 2022 Annual Meeting of Shareholders are incorporated by reference into Part III of this report.
Auditor Name	Ernst & Young LLP
Auditor Location	Raleigh, North Carolina
Auditor Firm ID	42