CREDIT FACILITIES (Notes)	3 Months Ended
Mar. 31, 2026
Line of Credit Facility [Abstract]
Short-term Debt [Text Block]	4. CREDIT FACILITY AND SHORT-TERM DEBT The ONE Gas Credit Agreement provides for a $1.5 billion revolving unsecured credit facility, which includes a $20 million letter of credit subfacility and a $60 million swingline subfacility. Under the terms of the agreement, the Company may, subject to satisfaction of customary conditions and receipt of commitments from new or existing lenders, request an increase in total commitments of up to an additional $750 million. Proceeds from the agreement may be used for working capital, capital expenditures, acquisitions and mergers, the issuance of letters of credit, and other general corporate purposes. The ONE Gas Credit Agreement contains certain financial, operational, and legal covenants. Among other things, these covenants include maintaining ONE Gas’ total debt-to-capital ratio, excluding the debt of KGSS-I, of no more than 70 percent at the end of any calendar quarter. At March 31, 2026, our total debt-to-capital ratio, excluding KGSS-I, was 47.1 percent and we were in compliance with all covenants under the ONE Gas Credit Agreement. We may reduce the unutilized portion of the ONE Gas Credit Agreement in whole or in part without premium or penalty. The ONE Gas Credit Agreement contains customary events of default. Upon the occurrence of certain events of default, our obligations under the ONE Gas Credit Agreement may be accelerated and the commitments may be terminated. At March 31, 2026, we had approximately $2.4 million in letters of credit issued and no borrowings under the ONE Gas Credit Agreement, with approximately $1.5 billion of remaining credit, which is available to repay our commercial paper borrowings and for other permitted purposes. Under our commercial paper program, we may issue unsecured commercial paper up to the maximum amount of $1.5 billion to fund short-term borrowing needs. The maturities of the commercial paper vary but may not exceed 270 days from the date of issue. Commercial paper is generally sold at par less a discount representing an interest factor. At March 31, 2026 and December 31, 2025, we had $759.7 million and $737.4 million of commercial paper outstanding with a weighted-average interest rate of 4.14 percent and 3.94 percent, respectively.

The ONE Gas Credit Agreement provides for a $1.5 billion revolving unsecured credit facility, which includes a $20 million letter of credit subfacility and a $60 million swingline subfacility. Under the terms of the agreement, the Company may, subject to satisfaction of customary conditions and receipt of commitments from new or existing lenders, request an increase in total commitments of up to an additional $750 million. Proceeds from the agreement may be used for working capital, capital expenditures, acquisitions and mergers, the issuance of letters of credit, and other general corporate purposes.

The ONE Gas Credit Agreement contains certain financial, operational, and legal covenants. Among other things, these covenants include maintaining ONE Gas’ total debt-to-capital ratio, excluding the debt of KGSS-I, of no more than 70 percent at the end of any calendar quarter. At March 31, 2026, our total debt-to-capital ratio, excluding KGSS-I, was 47.1 percent and we were in compliance with all covenants under the ONE Gas Credit Agreement. We may reduce the unutilized portion of the ONE Gas Credit Agreement in whole or in part without premium or penalty. The ONE Gas Credit Agreement contains customary events of default. Upon the occurrence of certain events of default, our obligations under the ONE Gas Credit Agreement may be accelerated and the commitments may be terminated.

At March 31, 2026, we had approximately $2.4 million in letters of credit issued and no borrowings under the ONE Gas Credit Agreement, with approximately $1.5 billion of remaining credit, which is available to repay our commercial paper borrowings and for other permitted purposes.

Under our commercial paper program, we may issue unsecured commercial paper up to the maximum amount of $1.5 billion to fund short-term borrowing needs. The maturities of the commercial paper vary but may not exceed 270 days from the date of issue. Commercial paper is generally sold at par less a discount representing an interest factor. At March 31, 2026 and December 31, 2025, we had $759.7 million and $737.4 million of commercial paper outstanding with a weighted-average interest rate of 4.14 percent and 3.94 percent, respectively.