| DEI 8-K (Details) | Oct. 28, 2019 |
| 8-K [Abstract] | |
| Document Information [Text Block] | UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 (Date of report) October 28, 2019 (Date of earliest event reported) October 28, 2019 ONE Gas, Inc. (Exact name of registrant as specified in its charter) Oklahoma 001-36108 46-3561936 (State or other jurisdiction (Commission (IRS Employer of incorporation) File Number) Identification No.) 15 East Fifth Street; Tulsa, OK (Address of principal executive offices) 74103 (Zip code) (918) 947-7000 (Registrant’s telephone number, including area code) Not Applicable (Former name or former address, if changed since last report) Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ☐ Written communication pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each class Trading Symbol Name of exchange on which registered Common Stock, par value $0.01 per share OGS New York Stock Exchange Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2). ☐ Emerging growth company If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. |
| Document Information [Line Items] | |
| Entity Central Index Key | 0001587732 |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Entity Incorporation, State or Country Code | OK |
| Document Period End Date | Oct. 28, 2019 |
| Entity File Number | 001-36108 |
| Entity Tax Identification Number | 46-3561936 |
| Entity Address, Postal Zip Code | 74103 |
| City Area Code | (918) |
| Local Phone Number | 947-7000 |
| Trading Symbol | OGS |
| Security Exchange Name | NYSE |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Document Type | 8-K |
| Entity Registrant Name | ONE Gas, Inc. |
| Entity Address, Address Line One | 15 East Fifth Street; |
| Entity Address, City or Town | Tulsa, |
| Entity Address, State or Province | OK |
