Document and Entity Information
Jul. 20, 2020
Cover [Abstract]  
Amendment Flag false
Entity Central Index Key 0001587732
Document Type 8-K
Document Period End Date Jul. 20, 2020
Entity Registrant Name ONE Gas, Inc.
Entity Incorporation State Country Code OK
Entity File Number 001-36108
Entity Tax Identification Number 46-3561936
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
City Area Code (918)
Local Phone Number 947-7000
Written Communications false
Soliciting Material false
Pre Commencement Tender Offer false
Pre Commencement Issuer Tender Offer false
Security 12b Title Common Stock, par value $0.01 per share
Trading Symbol OGS
Security Exchange Name NYSE
Entity Emerging Growth Company false