COMMITMENTS AND CONTINGENCIES (Notes)	9 Months Ended
Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Environmental Matters and Pipeline Safety - The operation of pipelines, plants and other facilities for the gathering, processing, transportation and storage of natural gas, NGLs, condensate and other products is subject to numerous and complex laws and regulations pertaining to health, safety and the environment. As an owner and/or operator of these facilities, we must comply with United States laws and regulations at the federal, state, local and tribal levels that relate to air and water quality, hazardous and solid waste management and disposal, cultural resource protection and other environmental matters. The cost of planning, designing, constructing and operating pipelines, plants and other facilities must incorporate compliance with these laws and regulations and safety standards. Failure to comply with these laws and regulations may trigger a variety of administrative, civil and potentially criminal enforcement measures, including citizen suits, which can include the assessment of monetary penalties, the imposition of remedial requirements and the issuance of injunctions or restrictions on operation or construction. Management believes that, based on currently known information, compliance with these laws and regulations will not have a material adverse effect on our results of operations, financial condition or cash flows. Regulatory - The Tax Cuts and Jobs Act made extensive changes to the U.S. tax laws and includes provisions that reduce the U.S. corporate tax rate to 21 percent from 35 percent, increase expensing for capital investment, and limit the interest deduction and use of net operating losses to offset future taxable income. The Tax Cuts and Jobs Act may reduce future tariff rates charged on our regulated pipelines. The rates charged to our customers have generally been established through shipper specific negotiation, discounts and negotiated settlements, which do not ascribe any specific cost of service elements. We expect future tariff rate changes, if any, related to the change in the U.S. corporate tax rate to be established prospectively over time on a similar negotiated basis. In July 2018, the FERC issued a final rule on the impact of the Tax Cuts and Jobs Act on FERC-regulated rates for natural gas pipelines, which indicated that a reduction in rates, if any, related to the decrease in the corporate tax rate would be prospective only. We do not expect the impact of this final rule to materially affect us. The July 2018 final rule, which incorporates the Order on Rehearing on the Commission’s Policy for Recovery of Income Tax Costs, made adjustments to the FERC’s March 2018 revised policy statement for master limited partnerships, which no longer allows interstate natural gas and oil pipelines owned by master limited partnerships to recover an income tax allowance in cost of service rates. The final rule clarified that a master limited partnership with a C-corporation parent is eligible for an income tax allowance. We do not expect this FERC action to be material to our results of operations, as we are organized as a C-corporation. Further, regardless of organizational structure, we do not expect this FERC action to materially affect us, as the rates charged to our customers have generally been established through shipper specific negotiation, discounts and negotiated settlements, which do not ascribe any specific cost of service elements. The FERC allows regulated NGL pipelines an annual index adjustment to tariff rates, which is intended to allow recovery of changes in costs without a complicated cost of service filing. The FERC is expected to evaluate how best to incorporate the effects of new tax policies in its next calculation of the rate index in 2020 for indexing effective July 2021. We do not expect to be materially impacted by any such change in the index calculation, as our regulated NGL pipeline revenues are primarily under negotiated agreements. Legal Proceedings - Gas Index Pricing Litigation - As previously reported, in March 2017, the United States District Court for the District of Nevada (the District Court) granted summary judgment to ONEOK Energy Services Company, L.P. (OESC) in Sinclair Oil Corporation v. ONEOK Energy Services Company, L.P. (filed in the United States District Court for the District of Wyoming in September 2005, transferred to MDL-1566 in the Court). In September 2017, the District Court entered a final judgment in favor of OESC in Sinclair, which was appealed by Sinclair Oil Corporation to the Ninth Circuit Court of Appeals. On August 1, 2018, the Ninth Circuit Court of Appeals reversed the District Court’s granting of summary judgment and remanded the case back to the District Court. We expect that future charges, if any, from the ultimate resolution of the Sinclair case will not be material to our results of operations, financial position or cash flows. Other Legal Proceedings - We are a party to various other litigation matters and claims that have arisen in the normal course of our operations. While the results of these litigation matters and claims cannot be predicted with certainty, we believe the reasonably possible losses from such matters, individually and in the aggregate, are not material. Additionally, we believe the probable final outcome of such matters will not have a material adverse effect on our consolidated results of operations, financial position or cash flows.

COMMITMENTS AND CONTINGENCIES

Environmental Matters and Pipeline Safety - The operation of pipelines, plants and other facilities for the gathering, processing, transportation and storage of natural gas, NGLs, condensate and other products is subject to numerous and complex laws and regulations pertaining to health, safety and the environment. As an owner and/or operator of these facilities, we must comply with United States laws and regulations at the federal, state, local and tribal levels that relate to air and water quality, hazardous and solid waste management and disposal, cultural resource protection and other environmental matters. The cost of planning, designing, constructing and operating pipelines, plants and other facilities must incorporate compliance with these laws and regulations and safety standards. Failure to comply with these laws and regulations may trigger a variety of administrative, civil and potentially criminal enforcement measures, including citizen suits, which can include the assessment of monetary penalties, the imposition of remedial requirements and the issuance of injunctions or restrictions on operation or construction. Management believes that, based on currently known information, compliance with these laws and regulations will not have a material adverse effect on our results of operations, financial condition or cash flows.

Regulatory - The Tax Cuts and Jobs Act made extensive changes to the U.S. tax laws and includes provisions that reduce the U.S. corporate tax rate to 21 percent from 35 percent, increase expensing for capital investment, and limit the interest deduction and use of net operating losses to offset future taxable income. The Tax Cuts and Jobs Act may reduce future tariff rates charged on our regulated pipelines. The rates charged to our customers have generally been established through shipper specific negotiation, discounts and negotiated settlements, which do not ascribe any specific cost of service elements. We expect future tariff rate changes, if any, related to the change in the U.S. corporate tax rate to be established prospectively over time on a similar negotiated basis. In July 2018, the FERC issued a final rule on the impact of the Tax Cuts and Jobs Act on FERC-regulated rates for natural gas pipelines, which indicated that a reduction in rates, if any, related to the decrease in the corporate tax rate would be prospective only. We do not expect the impact of this final rule to materially affect us.

The July 2018 final rule, which incorporates the Order on Rehearing on the Commission’s Policy for Recovery of Income Tax Costs, made adjustments to the FERC’s March 2018 revised policy statement for master limited partnerships, which no longer allows interstate natural gas and oil pipelines owned by master limited partnerships to recover an income tax allowance in cost of service rates. The final rule clarified that a master limited partnership with a C-corporation parent is eligible for an income tax allowance. We do not expect this FERC action to be material to our results of operations, as we are organized as a C-corporation. Further, regardless of organizational structure, we do not expect this FERC action to materially affect us, as the rates charged to our customers have generally been established through shipper specific negotiation, discounts and negotiated settlements, which do not ascribe any specific cost of service elements.

The FERC allows regulated NGL pipelines an annual index adjustment to tariff rates, which is intended to allow recovery of changes in costs without a complicated cost of service filing. The FERC is expected to evaluate how best to incorporate the effects of new tax policies in its next calculation of the rate index in 2020 for indexing effective July 2021. We do not expect to be materially impacted by any such change in the index calculation, as our regulated NGL pipeline revenues are primarily under negotiated agreements.

Legal Proceedings - Gas Index Pricing Litigation - As previously reported, in March 2017, the United States District Court for the District of Nevada (the District Court) granted summary judgment to ONEOK Energy Services Company, L.P. (OESC) in Sinclair Oil Corporation v. ONEOK Energy Services Company, L.P. (filed in the United States District Court for the District of Wyoming in September 2005, transferred to MDL-1566 in the Court). In September 2017, the District Court entered a final judgment in favor of OESC in Sinclair, which was appealed by Sinclair Oil Corporation to the Ninth Circuit Court of Appeals. On August 1, 2018, the Ninth Circuit Court of Appeals reversed the District Court’s granting of summary judgment and remanded the case back to the District Court. We expect that future charges, if any, from the ultimate resolution of the Sinclair case will not be material to our results of operations, financial position or cash flows.

Other Legal Proceedings - We are a party to various other litigation matters and claims that have arisen in the normal course of our operations. While the results of these litigation matters and claims cannot be predicted with certainty, we believe the reasonably possible losses from such matters, individually and in the aggregate, are not material. Additionally, we believe the probable final outcome of such matters will not have a material adverse effect on our consolidated results of operations, financial position or cash flows.