Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 21, 2022	Jun. 30, 2021
Document Information [Line Items]
Entity Central Index Key	0001587732
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	false
Document Type	10-K
Entity Information
City Area Code	(918)
Document Period End Date	Dec. 31, 2021
Current Fiscal Year End Date	--12-31
Document Annual Report	true
Document Transition Report	false
Entity Address, Address Line One	15 East Fifth Street
Entity Address, City or Town	Tulsa,
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	74103
Local Phone Number	947-7000
Entity Common Stock, Shares Outstanding		53,633,445
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity File Number	001-36108
Entity Incorporation, State or Country Code	OK
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Registrant Name	ONE Gas, Inc.
Entity Tax Identification Number	46-3561936
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Small Business	false
Entity Shell Company	false
Entity Public Float			$ 3,800,000,000
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	OGS
Security Exchange Name	NYSE
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference [Text Block]	Portions of the definitive proxy statement to be delivered to shareholders in connection with the Annual Meeting of Shareholders to be held May 26, 2022, are incorporated by reference in Part III.