ONEOK (OKE) 10-Q 31 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 22, 2018
Document Information [Line Items]
Entity Registrant Name	ONEOK INC /NEW/
Entity Central Index Key	1,039,684
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		411,361,477
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues
Commodity sales	$ 3,083,625	$ 2,322,534	$ 8,578,891	$ 6,700,260
Services	310,265	583,832	877,605	1,681,489
Total revenues	3,393,890	2,906,366	9,456,496	8,381,749
Cost of sales and fuel (exclusive of items shown separately below)	2,560,765	2,229,416	7,104,609	6,464,281
Operations and maintenance	206,247	179,693	589,465	532,529
Depreciation and amortization	107,383	102,298	317,908	302,566
Impairment of long-lived assets	0	15,970	0	15,970
General taxes	24,124	24,641	81,263	76,098
Gain on sale of assets	(163)	(274)	(348)	(904)
Operating income	495,534	354,622	1,363,599	991,209
Equity in net earnings from investments (Note I)	39,313	40,058	116,070	118,985
Impairment of equity investments (Note I)	0	(4,270)	0	(4,270)
Allowance for equity funds used during construction	2,294	40	3,328	75
Other income	5,072	3,296	7,667	11,670
Other expense	(3,404)	(3,554)	(11,104)	(31,581)
Interest expense (net of capitalized interest of $8,326, $1,068, $15,498, and $4,254, respectively)	(121,910)	(126,533)	(351,131)	(361,468)
Income before income taxes	416,899	263,659	1,128,429	724,620
Income taxes	(102,983)	(97,128)	(266,285)	(195,913)
Net income	313,916	166,531	862,144	528,707
Less: Net income attributable to noncontrolling interests	657	789	3,329	203,911
Net income attributable to ONEOK	313,259	165,742	858,815	324,796
Less: Preferred stock dividends	275	276	825	493
Net income available to common shareholders	$ 312,984	$ 165,466	$ 857,990	$ 324,303
Basic earnings per common share	$ 0.76	$ 0.43	$ 2.09	$ 1.21
Diluted earnings per common share	$ 0.75	$ 0.43	$ 2.07	$ 1.20
Average shares (thousands)
Basic	412,117	380,907	411,400	268,108
Diluted	414,847	383,419	414,035	270,349
Dividends declared per share of common stock	$ 0.825	$ 0.745	$ 2.390	$ 1.975

CONSOLIDATED STATEMENT OF INCOM

CONSOLIDATED STATEMENT OF INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest expense (net of capitalized interest)	$ 8,326	$ 1,068	$ 15,498	$ 4,254

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income	$ 313,916	$ 166,531	$ 862,144	$ 528,707
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax of $1,054, $12,217, $(3,204) and $8,689, respectively	(3,526)	(20,620)	10,729	(1,287)
Realized (gains) losses on derivatives recognized in net income, net of tax of $(5,752), $(7,671), $(12,962) and $(13,077), respectively	19,261	13,062	43,397	40,272
Change in pension and postretirement benefit plan liability, net of tax of $(966), $(1,360), $(2,714) and $(4,081), respectively	3,236	2,041	9,086	6,122
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax of $(442), $100, $(1,578) and $288, respectively	1,480	(169)	5,281	(1,214)
Total other comprehensive income (loss), net of tax	20,451	(5,686)	68,493	43,893
Comprehensive income	334,367	160,845	930,637	572,600
Less: Comprehensive income attributable to noncontrolling interests	657	789	3,329	234,937
Comprehensive income attributable to ONEOK	$ 333,710	$ 160,056	$ 927,308	$ 337,663

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (PARANTHETICAL) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Unrealized Gains (Losses) on Derivatives, Tax	$ 1,054	$ 12,217	$ (3,204)	$ 8,689
Realized (Gains) Losses on Derivatives in Net Income, Tax	(5,752)	(7,671)	(12,962)	(13,077)
Change in Pension and Postretirement Benefit Plan Liability, Tax	(966)	(1,360)	(2,714)	(4,081)
Other Comprehensive Income (Loss) on Investments in Unconsolidated Affiliates, Tax	$ (442)	$ 100	$ (1,578)	$ 288

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 84,464	$ 37,193
Accounts receivable, net	1,085,075	1,202,951
Materials and supplies	128,574	90,301
Natural gas and natural gas liquids in storage	426,293	342,293
Commodity imbalances	22,162	38,712
Other current assets	61,340	53,008
Total current assets	1,807,908	1,764,458
Property, plant and equipment
Property, plant and equipment	17,120,187	15,559,667
Accumulated depreciation and amortization	3,159,660	2,861,541
Net property, plant and equipment	13,960,527	12,698,126
Investments and other assets
Investments in unconsolidated affiliates	981,592	1,003,156
Goodwill and intangible assets	970,117	993,460
Deferred income taxes	0	205,907
Other assets	191,170	180,830
Total investments and other assets	2,142,879	2,383,353
Total assets	17,911,314	16,845,937
Current liabilities
Current maturities of long-term debt (Note D)	507,650	432,650
Short-term borrowings (Note D)	120,000	614,673
Accounts payable	1,339,507	1,140,571
Commodity imbalances	162,990	164,161
Accrued interest	111,747	135,309
Other current liabilities	208,312	179,971
Total current liabilities	2,450,206	2,667,335
Long-term debt, excluding current maturities (Note D)	8,325,708	8,091,629
Deferred credits and other liabilities
Deferred income taxes	132,242	52,697
Other deferred credits	350,400	348,924
Total deferred credits and other liabilities	482,642	401,621
Commitments and contingencies (Note J)
Equity (Note E)
Preferred stock, $0.01 par value: issued 20,000 shares at September 30, 2018, and December 31, 2017	0	0
Common stock, $0.01 par value: authorized 1,200,000,000 shares, issued 445,016,234 shares and outstanding 411,358,838 shares at September 30, 2018; issued 423,166,234 shares and outstanding 388,703,543 shares at December 31, 2017	4,450	4,232
Paid-in Capital	7,662,673	6,588,878
Accumulated other comprehensive loss (Note F)	(158,138)	(188,530)
Retained Earnings	0	0
Treasury stock, at cost: 33,657,396 shares at September 30, 2018, and 34,462,691 shares at December 31, 2017	(856,227)	(876,713)
Total ONEOK Shareholders' Equity	6,652,758	5,527,867
Noncontrolling interests in consolidated subsidiaries	0	157,485
Total equity	6,652,758	5,685,352
Total liabilities and equity	$ 17,911,314	$ 16,845,937

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Equity (Note E)
Common stock, shares, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares, authorized (in shares)	1,200,000,000	1,200,000,000
Common stock, shares, issued (in shares)	445,016,234	423,166,234
Common stock, shares, outstanding (in shares)	411,358,838	388,703,543
Treasury stock, shares (in shares)	33,657,396	34,462,691
Preferred stock, shares, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares, issued (in shares)	20,000	20,000

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net income	$ 862,144	$ 528,707
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	317,908	302,566
Impairment charges	0	20,240
Noncash contribution of preferred stock, net of tax	0	12,600
Equity in net earnings from investments	(116,070)	(118,985)
Distributions received from unconsolidated affiliates	125,824	124,517
Deferred income taxes	264,509	186,584
Share-based compensation expense	23,963	19,688
Pension and postretirement benefit expense, net of contributions	(2,902)	818
Allowance for equity funds used during construction	(3,328)	(75)
Gain on sale of assets	(348)	(904)
Changes in assets and liabilities:
Accounts receivable	117,876	(33,224)
Natural gas and natural gas liquids in storage	(91,170)	(174,232)
Accounts payable	(41,837)	82,174
Commodity imbalances, net	15,379	(4,004)
Risk-management assets and liabilities	66,966	34,534
Other assets and liabilities, net	(22,464)	(45,008)
Cash provided by operating activities	1,516,450	935,996
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	(1,309,655)	(330,431)
Cash paid for acquisition	(195,000)	0
Contributions to unconsolidated affiliates	(831)	(87,653)
Distributions received from unconsolidated affiliates in excess of cumulative earnings	19,613	21,577
Proceeds from sale of assets	1,053	1,910
Cash used in investing activities	(1,484,820)	(394,597)
Financing activities
Dividends paid	(983,068)	(543,445)
Distributions to noncontrolling interests	(3,500)	(275,060)
Borrowing (repayment) of short-term borrowings, net	(494,673)	(178,027)
Issuance of long-term debt, net of discounts	1,245,773	1,190,067
Debt financing costs	(11,301)	(11,340)
Repayment of long-term debt	(930,738)	(992,864)
Issuance of common stock	1,195,128	45,849
Other, net	(1,980)	(13,778)
Cash provided by (used in) financing activities	15,641	(778,598)
Change in cash and cash equivalents	47,271	(237,199)
Cash and cash equivalents at beginning of period	37,193	248,875
Cash and cash equivalents at end of period	$ 84,464	$ 11,676

CONSOLIDATED STATEMENT OF CHANG

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Common Stock	Preferred Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock	Noncontrolling Interests in Consolidated Subsidiaries
Cumulative effect adjustment for adoption of ASUs	$ 73,368	$ 0	$ 0	$ 0	$ 0	$ 73,368	$ 0	$ 0
Shares, issued, beginning balance at Dec. 31, 2016		245,811,180	0
Total equity, beginning balance at Dec. 31, 2016	3,428,915	$ 2,458	$ 0	1,234,314	(154,350)	0	(893,677)	3,240,170
Net income	528,707	0	0	0	0	324,796	0	203,911
Other comprehensive income (loss)	43,893	0	0	0	12,867	0	0	31,026
Preferred Stock Issued	20,000	0	0	20,000	0	0	0	0
Common Stock Dividends	(543,076)	$ 0	$ 0	(144,912)	0	(398,164)	0	0
Stock Issued During Period, Shares, Other		1,181,493	20,000
Stock Issued During Period, Value, Other	80,790	$ 12	$ 0	68,032	0	0	12,746	0
Preferred stock dividends	(493)	0	0	(493)	0	0	0	0
Distributions to Noncontrolling Interests	(275,060)	$ 0	0	0	0	0	0	(275,060)
Stock Issued During Period, Shares, Acquisitions		168,920,831
Acquisition of ONEOK Partners' Noncontrolling Interests	2,146,462	$ 1,689	0	5,228,580	(40,288)	0	0	(3,043,519)
Other	12,877	$ 0	$ 0	12,517	0	0	0	360
Shares, issued, ending balance at Sep. 30, 2017		415,913,504	20,000
Total equity, ending balance at Sep. 30, 2017	5,516,383	$ 4,159	$ 0	6,418,038	(181,771)	0	(880,931)	156,888
Cumulative effect adjustment for adoption of ASUs	1,719	$ 0	$ 0	0	(38,101)	39,803	0	17
Shares, issued, beginning balance at Dec. 31, 2017		423,166,234	20,000
Total equity, beginning balance at Dec. 31, 2017	5,685,352	$ 4,232	$ 0	6,588,878	(188,530)	0	(876,713)	157,485
Net income	862,144	0	0	0	0	858,815	0	3,329
Other comprehensive income (loss)	68,493	0	0	0	68,493	0	0	0
Common Stock Dividends	(983,425)	$ 0	0	(85,632)	0	(897,793)	0	0
Stock Issued During Period, Shares, Other		21,850,000
Stock Issued During Period, Value, Other	1,199,207	$ 218	0	1,178,503	0	0	20,486	0
Preferred stock dividends	(825)	0	0	0	0	(825)	0	0
Distributions to Noncontrolling Interests	(3,500)	0	0	0	0	0	0	(3,500)
Contributions from noncontrolling interests	16,449	0	0	0	0	0	0	16,449
Acquisition of noncontrolling interests	(195,000)	0	0	(21,220)	0	0	0	(173,780)
Other	2,144	$ 0	$ 0	2,144	0	0	0	0
Shares, issued, ending balance at Sep. 30, 2018		445,016,234	20,000
Total equity, ending balance at Sep. 30, 2018	$ 6,652,758	$ 4,450	$ 0	$ 7,662,673	$ (158,138)	$ 0	$ (856,227)	$ 0

CONSOLIDATED STATEMENT OF CHA_2

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY CONSOLIDATED STATEMENT OF CHANGES IN EQUITY Parenthetical - $ / shares	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017
Statement of Stockholders' Equity [Abstract]
Dividends paid (in dollars per share)	$ 0.825	$ 0.795	$ 0.77	$ 2.390	$ 1.975

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Notes)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Our accompanying unaudited consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC. These statements have been prepared in accordance with GAAP and reflect all adjustments that, in our opinion, are necessary for a fair statement of the results for the interim periods presented. All such adjustments are of a normal recurring nature. The 2017 year-end Consolidated Balance Sheet data was derived from our audited financial statements but does not include all disclosures required by GAAP. Certain reclassifications have been made in the prior-year financial statements to conform to the current year presentation. These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements in our Annual Report. Merger Transaction - On June 30, 2017, we completed the acquisition of all of the outstanding common units of ONEOK Partners that we did not already own at a fixed exchange ratio of 0.985 of a share of our common stock for each ONEOK Partners common unit. We issued 168.9 million shares of our common stock to third-party common unitholders of ONEOK Partners in exchange for all of the 171.5 million outstanding common units of ONEOK Partners that we previously did not own. As a result of the completion of the Merger Transaction, common units of ONEOK Partners are no longer publicly traded. Prior to June 30, 2017, we and our subsidiaries owned all of the general partner interest, which included incentive distribution rights, and a portion of the limited partner interest, which together represented a 41.2 percent ownership interest in ONEOK Partners. The earnings of ONEOK Partners that are attributed to its units held by the public until June 30, 2017, are reported as “Net income attributable to noncontrolling interest” in our accompanying Consolidated Statements of Income. Our general partner incentive distribution rights effectively terminated at the closing of the Merger Transaction. Our significant accounting policies are consistent with those disclosed in Note A of the Notes to Consolidated Financial Statements in our Annual Report, except as described below. Recently Issued Accounting Standards Update - Changes to GAAP are established by the Financial Accounting Standards Board (FASB) in the form of ASUs to the FASB Accounting Standards Codification. We consider the applicability and impact of all ASUs. ASUs not listed below were assessed and determined to be either not applicable or clarifications of ASUs listed below. We also exclude ASUs not yet adopted that were disclosed in our Annual Report to not materially impact us. The following tables provide a brief description of recent accounting pronouncements and our analysis of the effects on our financial statements: Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standards that were adopted ASU 2014-09, “Revenue from Contracts with Customers (Topic 606)” The standard outlines the principles an entity must apply to measure and recognize revenue for entities that enter into contracts to provide goods or services to their customers. The core principle is that an entity should recognize revenue at an amount that reflects the consideration to which the entity expects to be entitled in exchange for transferring goods or services to a customer. The amendment also requires more extensive disaggregated revenue disclosures in interim and annual financial statements. First quarter 2018 We adopted this standard on January 1, 2018, using the modified retrospective method. We recognized the cumulative effect of adopting the new revenue standard as an increase to beginning retained earnings of $1.7 million. Results for reporting periods beginning after January 1, 2018, are presented under the new standard, while prior periods are not adjusted and continue to be reported under the accounting standards in effect for those periods. The adoption of Topic 606 was not material to our net income; however, a significant portion of amounts historically presented as services revenues are now presented as a reduction to cost of sales and fuel. See Note K for discussion of these changes and additional disclosures. Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standards that were adopted ( continued ) ASU 2016-01, “Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities” The standard requires all equity investments, other than those accounted for using the equity method of accounting or those that result in consolidation of the investee, to be measured at fair value with changes in fair value recognized in net income, eliminates the available-for-sale classification for equity securities with readily determinable fair values and eliminates the cost method for equity investments without readily determinable fair values. First quarter 2018 We do not have any equity investments classified as available-for-sale or accounted for using the cost method; therefore, the impact of adopting of this standard was not material. ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments” The standard clarifies the classification of certain cash receipts and cash payments on the statement of cash flows where diversity in practice has been identified. First quarter 2018 The impact of adopting this standard was not material. ASU 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” The standard requires the service cost component of net benefit cost to be reported in the same line item or items as other compensation costs from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. First quarter 2018 We adopted this standard on January 1, 2018, and utilized the practical expedient to estimate the impact on the prior comparative period information presented. Immaterial reclassifications have been made to prior comparative period information to reflect the current period presentation. Prior to adoption, we expensed all components of the net periodic benefit costs for our pension and postretirement benefit plans in operations and maintenance expense. We now record only the service component of the net periodic benefit costs in operations and maintenance expense, with the remainder being recorded in other expense. There was no change to net income from the adoption of this standard. ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities” The standard more closely aligns hedge accounting with companies’ existing risk-management strategies by expanding the strategies eligible for hedge accounting, relaxing the timing requirements of hedge documentation and effectiveness assessments, permitting in certain cases, the use of qualitative assessments on an ongoing basis to assess hedge effectiveness, and requiring new disclosures and presentation. First quarter 2018 We adopted this standard in the first quarter 2018 and recorded an immaterial cumulative-effect adjustment to the opening balance of retained earnings and other comprehensive income to eliminate the separate measurement of hedge ineffectiveness. See Note C for changes to disclosures due to adopting this standard. ASU 2018-02, “Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. First quarter 2018 We adopted this standard in the first quarter 2018 and recorded a $38.1 million adjustment to retained earnings and accumulated other comprehensive income to eliminate the stranded tax effects resulting from the Tax Cuts and Jobs Act. Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standards that are not yet adopted ASU 2016-02, “Leases (Topic 842)” The standard requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous GAAP. It also requires qualitative disclosures along with specific quantitative disclosures by lessees and lessors to meet the objective of enabling users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. First quarter 2019 We are evaluating our current leases and other contracts that may be considered leases under the new standard and the impact on our internal controls, accounting policies and financial statements and disclosures. We have developed a database of our existing leases, and we have implemented accounting software to facilitate compliance with this standard. We are developing internal controls designed to ensure the completeness and accuracy of the data. Upon adoption of Topic 842, we expect to recognize right of use assets and lease liabilities not previously recorded on our Consolidated Balance Sheets and provide required footnote disclosures. We do not expect the impact of adopting this standard to be material to our Consolidated Financial Statements. We expect to elect the transition practical expedient, which allows us to not evaluate land easements that existed prior to January 1, 2019, and the optional transition method to record the adoption impact through a cumulative adjustment to equity. ASU 2018-07, “Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting” The standard aligns the measurement and classification guidance for share-based payments to nonemployees with the guidance for share-based payments to employees, with certain exceptions. First quarter 2019 We do not expect the adoption of this standard to materially impact us. ASU 2018-13, “Fair Value Measurement (Topic 820)” The standard modifies certain disclosure requirements for fair value measurements in Topic 820. First quarter 2020 We are evaluating the impact of this standard on us. ASU 2018-14, “Compensation - Retirement Benefits - Defined Benefit Plans - General (Topic 715-20)” The standard modifies the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. First quarter 2021 We are evaluating the impact of this standard on us. Goodwill Impairment Review - We assess our goodwill for impairment at least annually as of July 1. At July 1, 2018, we assessed qualitative factors to determine whether it was more likely than not that the fair value of each of our reporting units was less than its carrying amount. After assessing qualitative factors (including macroeconomic conditions, industry and market considerations, cost factors and overall financial performance), we determined that it was more likely than not that the fair value of each reporting unit was greater than its respective carrying value, that no further testing was necessary and that goodwill was not considered impaired.

FAIR VALUE MEASUREMENTS (Notes)

FAIR VALUE MEASUREMENTS (Notes)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Determining Fair Value - We define fair value as the price that would be received from the sale of an asset or the transfer of a liability in an orderly transaction between market participants at the measurement date. We use market and income approaches to determine the fair value of our assets and liabilities and consider the markets in which the transactions are executed. We measure the fair value of a group of financial assets and liabilities consistent with how a market participant would price the net risk exposure at the measurement date. While many of the contracts in our derivative portfolio are executed in liquid markets where price transparency exists, some contracts are executed in markets for which market prices may exist, but the market may be relatively inactive. This results in limited price transparency that requires management’s judgment and assumptions to estimate fair values. For certain transactions, we utilize modeling techniques using NYMEX-settled pricing data and implied forward LIBOR curves. Inputs into our fair value estimates include commodity-exchange prices, over-the-counter quotes, historical correlations of pricing data, data obtained from third-party pricing services and LIBOR and other liquid money-market instrument rates. We validate our valuation inputs with third-party information and settlement prices from other sources, where available. In addition, as prescribed by the income approach, we compute the fair value of our derivative portfolio by discounting the projected future cash flows from our derivative assets and liabilities to present value using interest-rate yields to calculate present-value discount factors derived from LIBOR, Eurodollar futures and the LIBOR interest-rate swaps market. We also contemplate the potential impact on market prices of liquidating positions in an orderly manner over a reasonable period of time under current market conditions. We consider current market data in evaluating counterparties’, as well as our own, nonperformance risk, net of collateral, by using specific and sector bond yields and monitoring the credit default swap markets. Although we use our best estimates to determine the fair value of the derivative contracts we have executed, the ultimate market prices realized could differ materially from our estimates. The fair value of our forward-starting interest-rate swaps are determined using financial models that incorporate the implied forward LIBOR yield curve for the same period as the future interest-rate swap settlements. Fair Value Hierarchy - At each balance sheet date, we utilize a fair value hierarchy to classify fair value amounts recognized or disclosed in our financial statements based on the observability of inputs used to estimate such fair value. The levels of the hierarchy are described below: • Level 1 - fair value measurements are based on unadjusted quoted prices for identical securities in active markets, including NYMEX-settled prices. These balances are composed predominantly of exchange-traded derivative contracts for natural gas and crude oil. • Level 2 - fair value measurements are based on significant observable pricing inputs, such as NYMEX-settled prices for natural gas and crude oil, and financial models that utilize implied forward LIBOR yield curves for interest-rate swaps. • Level 3 - fair value measurements are based on inputs that may include one or more unobservable inputs, including internally developed natural gas basis and NGL price curves that incorporate observable and unobservable market data from broker quotes, third-party pricing services, market volatilities derived from the most recent NYMEX close spot prices and forward LIBOR curves, and adjustments for the credit risk of our counterparties. We corroborate the data on which our fair value estimates are based using our market knowledge of recent transactions, analysis of historical correlations and validation with independent broker quotes. These balances categorized as Level 3 are composed of derivatives for natural gas and NGLs. We do not believe that our Level 3 fair value estimates have a material impact on our results of operations, as the majority of our derivatives are accounted for as hedges. Determining the appropriate fair value measurement classification within the fair value hierarchy requires management’s judgment regarding the degree to which market data is observable or corroborated by observable market data. We categorize derivatives for which fair value is determined using multiple inputs within a single level, based on the lowest level input that is significant to the fair value measurement in its entirety. Recurring Fair Value Measurements - The following tables set forth our recurring fair value measurements for the periods indicated: September 30, 2018 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 183 $ — $ 53,946 $ 54,129 $ (54,129 ) $ — Interest-rate contracts — 50,509 — 50,509 — 50,509 Total derivative assets $ 183 $ 50,509 $ 53,946 $ 104,638 $ (54,129 ) $ 50,509 Derivative liabilities Commodity contracts Financial contracts $ (17,337 ) $ — $ (83,013 ) $ (100,350 ) $ 100,350 $ — Physical contracts — — (2,010 ) (2,010 ) — (2,010 ) Total derivative liabilities $ (17,337 ) $ — $ (85,023 ) $ (102,360 ) $ 100,350 $ (2,010 ) (a) - Derivative assets and liabilities are presented in our Consolidated Balance Sheets on a net basis. We net derivative assets and liabilities when a legally enforceable master-netting arrangement exists between the counterparty to a derivative contract and us. At September 30, 2018 , we held no cash and posted $67.8 million of cash with various counterparties, including $46.2 million of cash collateral that is offsetting derivative net liability positions under master-netting arrangements in the table above. The remaining $21.6 million of cash collateral in excess of derivative net liability positions is included in other current assets in our Consolidated Balance Sheets. December 31, 2017 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 4,252 $ — $ 20,203 $ 24,455 $ (24,455 ) $ — Interest rate contracts — 49,960 — 49,960 — 49,960 Total derivative assets $ 4,252 $ 49,960 $ 20,203 $ 74,415 $ (24,455 ) $ 49,960 Derivative liabilities Commodity contracts Financial contracts $ (5,708 ) $ — $ (48,260 ) $ (53,968 ) $ 53,936 $ (32 ) Physical contracts — — (4,781 ) (4,781 ) — (4,781 ) Total derivative liabilities $ (5,708 ) $ — $ (53,041 ) $ (58,749 ) $ 53,936 $ (4,813 ) (a) - Derivative assets and liabilities are presented in our Consolidated Balance Sheets on a net basis. We net derivative assets and liabilities when a legally enforceable master-netting arrangement exists between the counterparty to a derivative contract and us. At December 31, 2017 , we held no cash and posted $49.7 million of cash with various counterparties, including $29.5 million of cash collateral that is offsetting derivative net liability positions under master-netting arrangements in the table above. The remaining $20.2 million of cash collateral in excess of derivative net liability positions is included in other current assets in our Consolidated Balance Sheets. The following table sets forth a reconciliation of our Level 3 fair value measurements for the periods indicated: Three Months Ended Nine Months Ended September 30, September 30, Derivative Assets (Liabilities) 2018 2017 2018 2017 ( Thousands of dollars ) Net assets (liabilities) at beginning of period $ (23,501 ) $ 750 $ (32,838 ) $ (23,319 ) Total realized/unrealized gains (losses): Included in earnings (a) (22 ) (675 ) (122 ) (417 ) Included in other comprehensive income (loss) (7,554 ) (26,581 ) 1,883 (2,770 ) Net assets (liabilities) at end of period $ (31,077 ) $ (26,506 ) $ (31,077 ) $ (26,506 ) (a) - Included in commodity sales revenues in our Consolidated Statements of Income. Realized/unrealized gains (losses) include the realization of our derivative contracts through maturity. During the three and nine months ended September 30, 2018 and 2017 , gains or losses included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the end of each reporting period were not material. We recognize transfers into and out of the levels in the fair value hierarc hy as of the end of each reporting period. During the three and nine months ended September 30, 2018 and 2017 , there were no transfers between levels. Other Financial Instruments - The approximate fair value of cash and cash equivalents, accounts receivable, accounts payable and short-term borrowings is equal to book value due to the short-term nature of these items. Our cash and cash equivalents are composed of bank and money market accounts and are classified as Level 1. Our short-term borrowings are classified as Level 2 since the estimated fair value of the short-term borrowings can be determined using information available in the commercial paper market. The estimated fair value of our consolidated long-term debt, including current maturities, was $9.3 billion at September 30, 2018 , and December 31, 2017 . The book value of our consolidated long-term debt, including current maturities, was $8.8 billion and $8.5 billion at September 30, 2018 , and December 31, 2017 , respectively. The estimated fair value of the aggregate senior notes outstanding was determined using quoted market prices for similar issues with similar terms and maturities. The estimated fair value of our consolidated long-term debt is classified as Level 2.

RISK MANAGEMENT AND HEDGING ACT

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES (Notes)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES	RISK-MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES Risk-Management Activities - We are sensitive to changes in natural gas, crude oil and NGL prices, principally as a result of contractual terms under which these commodities are processed, purchased and sold. We are also subject to the risk of interest-rate fluctuation in the normal course of business. We use physical-forward purchases and sales and financial derivatives to secure a certain price for a portion of our natural gas, condensate and NGL products; to reduce our exposure to commodity price and interest-rate fluctuations; and to achieve more predictable cash flows. We follow established policies and procedures to assess risk and approve, monitor and report our risk-management activities. We have not used these instruments for trading purposes. Commodity price risk - Commodity price risk refers to the risk of loss in cash flows and future earnings arising from adverse changes in the price of natural gas, NGLs and condensate. We use the following commodity derivative instruments to reduce the near-term commodity price risk associated with a portion of the forecasted sales of these commodities: • Futures contracts - Standardized contracts to purchase or sell natural gas and crude oil for future delivery or settlement under the provisions of exchange regulations; • Forward contracts - Nonstandardized commitments between two parties to purchase or sell natural gas, crude oil or NGLs for future physical delivery. These contracts are typically nontransferable and can only be canceled with the consent of both parties; • Swaps - Exchange of one or more payments based on the value of one or more commodities. These instruments transfer the financial risk associated with a future change in value between the counterparties of the transaction, without also conveying ownership interest in the asset or liability; and • Options - Contractual agreements that give the holder the right, but not the obligation, to buy or sell a fixed quantity of a commodity at a fixed price within a specified period of time. Options may either be standardized and exchange-traded or customized and nonexchange-traded. We may also use other instruments including collars to mitigate commodity price risk. A collar is a combination of a purchased put option and a sold call option, which places a floor and a ceiling price for commodity sales being hedged. In our Natural Gas Gathering and Processing segment, we are exposed to commodity price risk as a result of retaining a portion of the commodity sales proceeds associated with our POP with fee contracts. Under certain POP with fee contracts, our fees and POP percentage may increase or decrease if production volumes, delivery pressures or commodity prices change relative to specified thresholds. We also are exposed to basis risk between the various production and market locations where we buy and sell commodities. As part of our hedging strategy, we use the previously described commodity derivative financial instruments and physical-forward contracts to reduce the impact of price fluctuations related to natural gas, NGLs and condensate. In our Natural Gas Liquids segment, we are primarily exposed to commodity price risk resulting from the relative values of the various NGL products to each other, the value of NGLs in storage and the relative value of NGLs to natural gas. We are also exposed to location price differential risk as a result of the relative value of NGL purchases at one location and sales at another location, primarily related to our optimization and marketing businesses. As part of our hedging strategy, we utilize physical-forward contracts and commodity derivative financial instruments to reduce the impact of price fluctuations related to NGLs. In our Natural Gas Pipelines segment, we are exposed to commodity price risk because our intrastate and interstate natural gas pipelines retain natural gas from our customers for operations or as part of our fee for services provided. When the amount of natural gas consumed in operations by these pipelines differs from the amount provided by our customers, our pipelines must buy or sell natural gas, or store or use natural gas from inventory, which can expose this segment to commodity price risk depending on the regulatory treatment for this activity. To the extent that commodity price risk in our Natural Gas Pipelines segment is not mitigated by fuel cost-recovery mechanisms, we may use physical-forward sales or purchases to reduce the impact of price fluctuations related to natural gas. At September 30, 2018 , and December 31, 2017 , there were no financial derivative instruments with respect to our natural gas pipeline operations. Interest-rate risk - We manage interest-rate risk through the use of fixed-rate debt, floating-rate debt, interest-rate swaps and treasury lock contracts. Interest-rate swaps are agreements to exchange interest payments at some future point based on specified notional amounts. In 2018, we entered into $1.5 billion of forward-starting interest-rate swaps and treasury lock contracts to hedge the variability of interest payments on a portion of our forecasted debt issuances that may result from changes in the benchmark interest rate before the debt is issued. We also settled $1.0 billion of our forward-starting interest rate swaps and treasury lock contracts related to our underwritten public offering of $1.25 billion senior unsecured notes completed in July 2018, and the remaining $500 million of our interest-rate swaps used to hedge our LIBOR-based interest payments. At September 30, 2018 , and December 31, 2017 , we had forward-starting interest-rate swaps with notional amounts totaling $1.8 billion and $1.3 billion , respectively, to hedge the variability of interest payments on a portion of our forecasted debt issuances. At December 31, 2017 , we had interest-rate swaps with a notional amount totaling $500 million to hedge the variability of our LIBOR-based interest payments. All of our interest-rate swaps are designated as cash flow hedges. Accounting Treatment - Our accounting treatment of derivative instruments is consistent with that disclosed in Note A of the Notes to Consolidated Financial Statements in our Annual Report, updated for the adoption of ASU 2017-12. Fair Values of Derivative Instruments - See Note B for a discussion of the inputs associated with our fair value measurements. The following table sets forth the fair values of our derivative instruments presented on a gross basis for the periods indicated: September 30, 2018 December 31, 2017 Location in our Consolidated Balance Sheets Assets (Liabilities) Assets (Liabilities) ( Thousands of dollars ) Derivatives designated as hedging instruments Commodity contracts Financial contracts Other current assets/other current liabilities $ 46,411 $ (84,174 ) $ 16,978 $ (42,819 ) Other assets/other deferred credits 3,461 (11,938 ) — (3,838 ) Physical contracts Other current liabilities — (1,898 ) — (4,781 ) Other deferred credits — (112 ) — — Interest-rate contracts Other current assets — — 1,330 — Other assets 50,509 — 48,630 — Total derivatives designated as hedging instruments 100,381 (98,122 ) 66,938 (51,438 ) Derivatives not designated as hedging instruments Commodity contracts Financial contracts Other current assets/other current liabilities 4,257 (4,238 ) 7,477 (7,311 ) Total derivatives not designated as hedging instruments 4,257 (4,238 ) 7,477 (7,311 ) Total derivatives $ 104,638 $ (102,360 ) $ 74,415 $ (58,749 ) Notional Quantities for Derivative Instruments - The following table sets forth the notional quantities for derivative instruments held for the periods indicated: September 30, 2018 December 31, 2017 Contract Type Purchased/ Payor Sold/ Receiver Purchased/ Payor Sold/ Receiver Derivatives designated as hedging instruments: Cash flow hedges Fixed price - Natural gas ( Bcf ) Futures and swaps — (36.1 ) — (24.5 ) - Crude oil and NGLs ( MMBbl ) Futures, forwards and swaps 7.2 (16.5 ) 3.5 (11.1 ) Basis - Natural gas ( Bcf ) Futures and swaps — (36.1 ) — (24.5 ) Interest-rate contracts ( Millions of dollars ) Swaps $ 1,750.0 $ — $ 1,750.0 $ — Derivatives not designated as hedging instruments: Fixed price - NGLs ( MMBbl ) Futures, forwards and swaps 0.2 (0.2 ) 0.8 (0.8 ) These notional amounts are used to summarize the volume of financial instruments; however, they do not reflect the extent to which the positions offset one another and, consequently, do not reflect our actual exposure to market or credit risk. Cash Flow Hedges - At September 30, 2018 , our Consolidated Balance Sheet reflected a net loss of $158.1 million in accumulated other comprehensive loss. The portion of accumulated other comprehensive loss attributable to our commodity derivative financial instruments is an unrealized loss of $37.2 million , net of tax, which is expected to be realized within the next 27 months as the forecasted transactions affect earnings. If commodity prices remain at current levels, we will realize approximately $30.5 million in net losses , net of tax, over the next 12 months and approximately $6.7 million in net losses , net of tax, thereafter. The amount deferred in accumulated other comprehensive loss attributable to our settled interest-rate swaps is a loss of $43.9 million , net of tax, which will be recognized over the life of the long-term, fixed-rate debt, including losses of $13.6 million , net of tax, that will be reclassified into earnings during the next 12 months as the hedged items affect earnings. The remaining amounts in accumulated other comprehensive loss are attributable primarily to our pension and postretirement benefit plan obligations, which are expected to be amortized over the average remaining service period of employees participating in these plans. The following table sets forth the unrealized effect of cash flow hedges recognized in other comprehensive income (loss) for the periods indicated: Three Months Ended Nine Months Ended Derivatives in Cash Flow Hedging Relationships September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Commodity contracts $ (30,783 ) $ (42,450 ) $ (56,246 ) $ (6,123 ) Interest-rate contracts 26,203 9,613 70,179 (3,853 ) Total unrealized gain (loss) recognized in other comprehensive income (loss) on derivatives $ (4,580 ) $ (32,837 ) $ 13,933 $ (9,976 ) The following table sets forth the effect of cash flow hedges in our Consolidated Statements of Income for the periods indicated: Derivatives in Cash Flow Hedging Relationships Location of Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Net Income Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Commodity contracts Commodity sales revenues $ (20,630 ) $ (15,913 ) $ (42,430 ) $ (38,028 ) Interest-rate contracts Interest expense (4,383 ) (4,820 ) (13,929 ) (15,321 ) Total gain (loss) reclassified from accumulated other comprehensive loss into net income on derivatives $ (25,013 ) $ (20,733 ) $ (56,359 ) $ (53,349 ) Credit Risk - We monitor the creditworthiness of our counterparties and compliance with policies and limits established by our Risk Oversight and Strategy Committee. We maintain credit policies with regard to our counterparties that we believe minimize overall credit risk. These policies include an evaluation of potential counterparties’ financial condition (including credit ratings, bond yields and credit default swap rates), collateral requirements under certain circumstances and the use of standardized master-netting agreements that allow us to net the positive and negative exposures associated with a single counterparty. We use internally developed credit ratings for counterparties that do not have a credit rating. From time to time, we may enter into financial derivative instruments that contain provisions that require us to maintain an investment-grade credit rating from S&P and/or Moody’s. If our credit ratings on our senior unsecured long-term debt were to decline below investment grade, the counterparties to the derivative instruments could request collateralization on derivative instruments in net liability positions. There were no financial derivative instruments with contingent features related to credit risk at September 30, 2018 . The counterparties to our derivative contracts typically consist of major energy companies, financial institutions and commercial and industrial end users. This concentration of counterparties may affect our overall exposure to credit risk, either positively or negatively, in that the counterparties may be affected similarly by changes in economic, regulatory or other conditions. Based on our policies, exposures, credit and other reserves, we do not anticipate a material adverse effect on our financial position or results of operations as a result of counterparty nonperformance. At September 30, 2018 , the credit exposure from our derivative assets is with investment-grade companies in the financial services sector.

DEBT DEBT (Notes)

DEBT DEBT (Notes)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt [Text Block]	DEBT The following table sets forth our consolidated debt for the periods indicated: September 30, December 31, ( Thousands of dollars ) Commercial paper outstanding, bearing a weighted-average interest rate of 2.85% and 2.23% as of September 30, 2018, and December 31, 2017, respectively. $ 120,000 $ 614,673 Senior unsecured obligations: $425,000 at 3.2% due September 2018 — 425,000 $1,000,000 term loan, rate of 2.87% as of December 31, 2017, due January 2019 — 500,000 $500,000 at 8.625% due March 2019 500,000 500,000 $300,000 at 3.8% due March 2020 300,000 300,000 $700,000 at 4.25% due February 2022 547,397 547,397 $900,000 at 3.375 % due October 2022 900,000 900,000 $425,000 at 5.0 % due September 2023 425,000 425,000 $500,000 at 7.5% due September 2023 500,000 500,000 $500,000 at 4.9 % due March 2025 500,000 500,000 $500,000 at 4.0% due July 2027 500,000 500,000 $800,000 at 4.55% due July 2028 800,000 — $100,000 at 6.875% due September 2028 100,000 100,000 $400,000 at 6.0% due June 2035 400,000 400,000 $600,000 at 6.65% due October 2036 600,000 600,000 $600,000 at 6.85% due October 2037 600,000 600,000 $650,000 at 6.125% due February 2041 650,000 650,000 $400,000 at 6.2% due September 2043 400,000 400,000 $700,000 at 4.95% due July 2047 700,000 700,000 $450,000 at 5.2% due July 2048 450,000 — Guardian Pipeline Weighted average 7.85% due December 2022 30,870 36,607 Total debt 9,023,267 9,198,677 Unamortized portion of terminated swaps 17,179 18,468 Unamortized debt issuance costs and discounts (87,088 ) (78,193 ) Current maturities of long-term debt (507,650 ) (432,650 ) Short-term borrowings (a) (120,000 ) (614,673 ) Long-term debt $ 8,325,708 $ 8,091,629 (a) - Individual issuances of commercial paper under our commercial paper program generally mature in 90 days or less. These issuances are supported by and reduce the borrowing capacity under our $2.5 Billion Credit Agreement. $2.5 Billion Credit Agreement - In June 2018, we extended the term of our $2.5 Billion Credit Agreement by one year to June 2023. Our $2.5 Billion Credit Agreement is a $2.5 billion revolving credit facility and contains certain financial, operational and legal covenants. Among other things, these covenants include maintaining a ratio of indebtedness to adjusted EBITDA (EBITDA, as defined in our $2.5 Billion Credit Agreement, adjusted for all noncash charges and increased for projected EBITDA from certain lender-approved capital expansion projects) of no more than 5.5 to 1 at September 30, 2018. During the third quarter 2018, we acquired the remaining 20 percent interest in WTLPG for $195 million, which increased the covenant to 5.5 to 1 for the third quarter 2018 and the two following quarters. Thereafter, the covenant will decrease to 5.0 to 1. Our $2.5 Billion Credit Agreement includes a $100 million sublimit for the issuance of standby letters of credit and a $200 million sublimit for swingline loans. Under the terms of our $2.5 Billion Credit Agreement, we may request an increase in the size of the facility to an aggregate of $3.5 billion by either commitments from new lenders or increased commitments from existing lenders. Our $2.5 Billion Credit Agreement contains provisions for an applicable margin rate and an annual facility fee, both of which adjust with changes in our credit ratings. Based on our current credit ratings, borrowings, if any, will accrue at LIBOR plus 110 basis points , and the annual facility fee is 15 basis points . We have the option to request an additional one-year extension, subject to lender approval, which may be used for working capital, capital expenditures, acquisitions and mergers, the issuance of letters of credit and for other general corporate purposes. At September 30, 2018 , we had no borrowings outstanding, our ratio of indebtedness to adjusted EBITDA was 3.5 to 1, and we were in compliance with all covenants under our $2.5 Billion Credit Agreement. Debt Issuances - In July 2018, we completed an underwritten public offering of $1.25 billion senior unsecured notes consisting of $800 million , 4.55 percent senior notes due 2028 and $450 million , 5.2 percent senior notes due 2048. The net proceeds, after deducting underwriting discounts, commissions and offering expenses, were $1.23 billion . The proceeds were used for general corporate purposes, which included repayment of existing indebtedness and funding capital expenditures. Debt Repayments - In August 2018, we repaid the $425 million , 3.2 percent senior notes due September 2018 with cash on hand. In January 2018, we repaid the remaining $500 million balance outstanding on the Term Loan Agreement due 2019 with a combination of cash on hand and short-term borrowings. Debt Guarantees - Effective June 30, 2017, with the Merger Transaction, we, ONEOK Partners and the Intermediate Partnership issued, to the extent not already in place, guarantees of the indebtedness of ONEOK and ONEOK Partners.

EQUITY (Notes)

EQUITY (Notes)	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
EQUITY	EQUITY Noncontrolling Interests - As a result of the Merger Transaction in 2017, we and our subsidiaries owned 100 percent of ONEOK Partners at September 30, 2018 , and December 31, 2017 . At December 31, 2017 , the caption “Noncontrolling interests” on our Consolidated Balance Sheet reflects only the 20 percent of WTLPG that we did not own. On July 31, 2018, we acquired the remaining 20 percent interest in WTLPG for $195 million with cash on hand. We are now the sole owner of the West Texas LPG pipeline system. Equity Issuances - In January 2018, we completed an underwritten public offering of 21.9 million shares of our common stock at a public offering price of $54.50 per share, generating net proceeds of $1.2 billion . We used the net proceeds from this offering to fund capital expenditures and for general corporate purposes, which included repaying a portion of our outstanding indebtedness. In July 2017, we established an “at-the-market” equity program for the offer and sale from time to time of our common stock up to an aggregate amount of $1 billion . The program allows us to offer and sell our common stock at prices we deem appropriate through a sales agent. Sales of our common stock may be made by means of ordinary brokers’ transactions on the NYSE, in block transactions or as otherwise agreed to between us and the sales agent. We are under no obligation to offer and sell common stock under the program. During the nine months ended September 30, 2018 , no shares were sold through our “at-the-market” equity program. During the year ended December 31, 2017, we sold 8.4 million shares of common stock through our “at-the-market” equity program that resulted in net proceeds of $448.3 million . The net proceeds from these issuances were used for general corporate purposes, including repayment of outstanding indebtedness and to fund capital expenditures. Dividends - Holders of our common stock share equally in any dividend declared by our board of directors, subject to the rights of the holders of outstanding preferred stock. Dividends paid on our common stock in February 2018, May 2018 and August 2018 were $0.77 , $0.795 and $0.825 per share, respectively. A dividend of $0.855 per share was declared for shareholders of record at the close of business on November 5, 2018 , payable November 14, 2018 . The Series E Preferred Stock pays quarterly dividends on each share of Series E Preferred Stock, when, as and if declared by our Board of Directors, at a rate of 5.5 percent per year. We paid dividends for the Series E Preferred Stock of $0.3 million each in February 2018, May 2018 and August 2018. Dividends totaling $0.3 million were declared for the Series E Preferred Stock and are payable November 14, 2018 . Cash Distributions - Prior to the consummation of the Merger Transaction, we received distributions from ONEOK Partners on our common and Class B units and our 2 percent general partner interest, which included our incentive distribution rights. As a result of the Merger Transaction in 2017, we are entitled to receive all available ONEOK Partners cash. Our incentive distribution rights effectively terminated at the closing of the Merger Transaction.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ACCUMULATED OTHER COMPREHENSIVE INCOME (Notes)	9 Months Ended
	Sep. 30, 2018
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	ACCUMULATED OTHER COMPREHENSIVE LOSS The following table sets forth the balance in accumulated other comprehensive loss for the period indicated: Unrealized Gains (Losses) on Risk- Management Assets/Liabilities (a) Pension and Postretirement Benefit Plan Obligations (a) (b) Unrealized Gains (Losses) on Risk- Management Assets/Liabilities of Unconsolidated Affiliates (a) Accumulated Other Comprehensive Loss (a) ( Thousands of dollars ) January 1, 2018 $ (81,915 ) $ (105,411 ) $ (1,204 ) $ (188,530 ) Other comprehensive income (loss) before reclassifications 10,729 (563 ) 5,336 15,502 Amounts reclassified from accumulated other comprehensive loss 43,397 9,649 (55 ) 52,991 Net current-period other comprehensive income (loss) attributable to ONEOK 54,126 9,086 5,281 68,493 Impact of adoption of ASU 2018-02 (c) (17,935 ) (20,166 ) — (38,101 ) September 30, 2018 $ (45,724 ) $ (116,491 ) $ 4,077 $ (158,138 ) (a) - All amounts are presented net of tax. (b) - Includes amounts related to supplemental executive retirement plan. (c) - We elected to adopt this guidance in the first quarter 2018, which allows a reclassification from accumulated other comprehensive income/loss to retained earnings for the stranded tax effects resulting from the Tax Cuts and Jobs Act. After adopting and applying this guidance, our accumulated other comprehensive loss balance does not include stranded taxes resulting from the Tax Cuts and Jobs Act. The following table sets forth the effect of reclassifications from accumulated other comprehensive loss in our Consolidated Statements of Income for the periods indicated: Details about Accumulated Other Components Three Months Ended Nine Months Ended Affected Line Item in the Statements of Income September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Risk-management assets/liabilities Commodity contracts $ (20,630 ) $ (15,913 ) $ (42,430 ) $ (38,028 ) Commodity sales revenues Interest-rate contracts (4,383 ) (4,820 ) (13,929 ) (15,321 ) Interest expense (25,013 ) (20,733 ) (56,359 ) (53,349 ) Income before income taxes 5,752 7,671 12,962 13,077 Income taxes (19,261 ) (13,062 ) (43,397 ) (40,272 ) Net income Noncontrolling interests — — — (18,146 ) Less: Net income attributable to noncontrolling interests $ (19,261 ) $ (13,062 ) $ (43,397 ) $ (22,126 ) Net income attributable to ONEOK Pension and postretirement benefit plan obligations (a) Amortization of net loss $ (4,592 ) $ (3,811 ) $ (13,776 ) $ (11,435 ) Other income (expense) Amortization of unrecognized prior service credit 415 415 1,245 1,245 Other income (expense) (4,177 ) (3,396 ) (12,531 ) (10,190 ) Income before income taxes 961 1,358 2,882 4,076 Income taxes $ (3,216 ) $ (2,038 ) $ (9,649 ) $ (6,114 ) Net income attributable to ONEOK Risk-management assets/liabilities of unconsolidated affiliates $ 52 $ (83 ) $ 71 $ (264 ) Equity in net earnings from investments (12 ) 31 (16 ) 59 Income taxes 40 (52 ) 55 (205 ) Net income Noncontrolling interests — — — (106 ) Less: Net income attributable to noncontrolling interests $ 40 $ (52 ) $ 55 $ (99 ) Net income attributable to ONEOK Total reclassifications for the period attributable to ONEOK $ (22,437 ) $ (15,152 ) $ (52,991 ) $ (28,339 ) Net income attributable to ONEOK (a) - These components of accumulated other comprehensive loss are included in the computation of net periodic benefit cost. See Note H for additional detail of our net periodic benefit cost.

EARNINGS PER SHARE EARNINGS PER

EARNINGS PER SHARE EARNINGS PER SHARE (Notes)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	EARNINGS PER SHARE The following tables set forth the computation of basic and diluted EPS for the periods indicated: Three Months Ended September 30, 2018 Income Shares Per Share Amount ( Thousands, except per share amounts ) Basic EPS Net income attributable to ONEOK available for common stock $ 312,984 412,117 $ 0.76 Diluted EPS Effect of dilutive securities — 2,730 Net income attributable to ONEOK available for common stock and common stock equivalents $ 312,984 414,847 $ 0.75 Three Months Ended September 30, 2017 Income Shares Per Share Amount ( Thousands, except per share amounts ) Basic EPS Net income attributable to ONEOK available for common stock $ 165,466 380,907 $ 0.43 Diluted EPS Effect of dilutive securities — 2,512 Net income attributable to ONEOK available for common stock and common stock equivalents $ 165,466 383,419 $ 0.43 Nine Months Ended September 30, 2018 Income Shares Per Share Amount ( Thousands, except per share amounts ) Basic EPS Net income attributable to ONEOK available for common stock $ 857,990 411,400 $ 2.09 Diluted EPS Effect of dilutive securities — 2,635 Net income attributable to ONEOK available for common stock and common stock equivalents $ 857,990 414,035 $ 2.07 Nine Months Ended September 30, 2017 Income Shares Per Share Amount ( Thousands, except per share amounts ) Basic EPS Net income attributable to ONEOK available for common stock $ 324,303 268,108 $ 1.21 Diluted EPS Effect of dilutive securities — 2,241 Net income attributable to ONEOK available for common stock and common stock equivalents $ 324,303 270,349 $ 1.20

EMPLOYEE BENEFIT PLANS EMPLOYEE

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Notes)	9 Months Ended
	Sep. 30, 2018
Defined Benefit Plan [Abstract]
EMPLOYEE BENEFIT PLANS	EMPLOYEE BENEFIT PLANS The following tables set forth the components of net periodic benefit cost for our pension and postretirement benefit plans for the periods indicated: Pension Benefits Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Components of net periodic benefit cost Service cost $ 1,832 $ 1,721 $ 5,496 $ 5,165 Interest cost 4,408 4,655 13,224 13,965 Expected return on plan assets (5,969 ) (5,336 ) (17,907 ) (16,008 ) Amortization of net loss 4,258 3,392 12,774 10,176 Net periodic benefit cost $ 4,529 $ 4,432 $ 13,587 $ 13,298 Postretirement Benefits Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Components of net periodic benefit cost Service cost $ 211 $ 165 $ 633 $ 495 Interest cost 527 565 1,581 1,695 Expected return on plan assets (672 ) (564 ) (2,016 ) (1,692 ) Amortization of prior service credit (415 ) (415 ) (1,245 ) (1,245 ) Amortization of net loss 334 419 1,002 1,259 Net periodic benefit cost (income) $ (15 ) $ 170 $ (45 ) $ 512

UNCONSOLIDATED AFFILIATES (Note

UNCONSOLIDATED AFFILIATES (Notes)	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
UNCONSOLIDATED AFFILIATES	UNCONSOLIDATED AFFILIATES Equity in Net Earnings from Investments - The following table sets forth our equity in net earnings from investments for the periods indicated: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Northern Border Pipeline $ 16,486 $ 16,440 $ 48,863 $ 50,879 Overland Pass Pipeline Company 16,081 15,793 48,714 44,243 Roadrunner Gas Transmission 6,303 4,898 16,803 14,192 Other 443 2,927 1,690 9,671 Equity in net earnings from investments $ 39,313 $ 40,058 $ 116,070 $ 118,985 Impairment of equity investments $ — $ (4,270 ) $ — $ (4,270 ) Unconsolidated Affiliates Financial Information - The following table sets forth summarized combined financial information of our unconsolidated affiliates for the periods indicated: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Income Statement Operating revenues $ 160,962 $ 163,627 $ 471,641 $ 475,510 Operating expenses $ 69,004 $ 69,740 $ 205,525 $ 206,141 Net income $ 85,361 $ 87,330 $ 247,754 $ 260,533 Distributions paid to us $ 47,197 $ 49,414 $ 145,437 $ 146,094 We incurred expenses in transactions with unconsolidated affiliates of $37.5 million and $39.9 million for the three months ended September 30, 2018 and 2017 , respectively, and $113.2 million and $116.0 million for the nine months ended September 30, 2018 and 2017 , respectively, primarily related to Overland Pass Pipeline Company and Northern Border Pipeline. Accounts payable to our equity-method investees at September 30, 2018 , and December 31, 2017 , were $12.6 million and $13.6 million , respectively. Northern Border Pipeline - The Northern Border Pipeline partnership agreement provides that distributions to Northern Border Pipeline’s partners are to be made on a pro rata basis according to each partner’s percentage interest. The Northern Border Pipeline Management Committee determines the amount and timing of such distributions. Any changes to, or suspension of, the cash distribution policy of Northern Border Pipeline requires the unanimous approval of the Northern Border Pipeline Management Committee. Cash distributions are equal to 100 percent of distributable cash flow as determined from Northern Border Pipeline’s financial statements based upon EBITDA less interest expense and maintenance capital expenditures. Loans or other advances from Northern Border Pipeline to its partners or affiliates are prohibited under its credit agreement. In the third quarter 2017, we made equity contributions of $83 million to Northern Border Pipeline. In 2018, we made no contributions to Northern Border Pipeline. Northern Border Pipeline entered into a settlement with shippers that was approved by the FERC in February 2018. The settlement provides for tiered tariff rate reductions beginning January 1, 2018, that will reduce tariff rates 12.5 percent by January 2020, compared with previous tariff rates, and requires new tariff rates to be established by January 2024. We do not expect the impact of lower tariff rates on Northern Border Pipeline’s earnings and cash distributions to be material to us. Overland Pass Pipeline Company - The Overland Pass Pipeline Company limited liability company agreement provides that distributions to Overland Pass Pipeline Company’s members are to be made on a pro rata basis according to each member’s percentage interest. The Overland Pass Pipeline Company Management Committee determines the amount and timing of such distributions. Any changes to, or suspension of, cash distributions from Overland Pass Pipeline Company requires the unanimous approval of the Overland Pass Pipeline Company Management Committee. Cash distributions are equal to 100 percent of available cash as defined in the limited liability company agreement. Roadrunner Gas Transmission - The Roadrunner limited liability company agreement provides that distributions to members are made on a pro rata basis according to each member’s ownership interest. As the operator, we have been delegated the authority to determine such distributions in accordance with, and on the frequency set forth in, the Roadrunner limited liability company agreement. Cash distributions are equal to 100 percent of available cash, as defined in the limited liability company agreement. During the nine months ended September 30, 2018 and 2017, we made contributions of $0.5 million and $4.0 million to Roadrunner, respectively. We have an operating agreement with Roadrunner that provides for reimbursement or payment to us for management services and certain operating costs. Reimbursements and payments from Roadrunner included in operating income in our Consolidated Statements of Income for the three and nine months ended September 30, 2018 and 2017 , were not material.

COMMITMENTS AND CONTINGENCIES (

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.

REVENUE REVENUE (Notes)

REVENUE REVENUE (Notes)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	REVENUES Adoption of ASC Topic 606: Revenue from Contracts with Customers - We adopted Topic 606 on January 1, 2018, using the modified retrospective method applied to contracts that were active as of January 1, 2018. Results for reporting periods beginning after January 1, 2018, are presented under Topic 606, while prior periods are not adjusted and continue to be reported under the accounting standards in effect for those periods. We recorded a net increase to the beginning balance of retained earnings of approximately $1.7 million as of January 1, 2018, due to the cumulative impact of adopting the standard, primarily related to the timing of revenue on transportation contracts with tiered rates that resulted in contract assets in our Natural Gas Pipelines segment, contributions in aid of construction from customers that resulted in contract liabilities and an adjustment to NGL inventory related to contractual fees in our Natural Gas Liquids Segment, as described below. Based on the new guidance, we determined that certain Natural Gas Gathering and Processing segment POP with fee contracts and Natural Gas Liquids segment exchange services contracts that include the purchase of commodities are supplier contracts. Therefore, contractual fees in these identified contracts are now recorded as a reduction of the commodity purchase price in cost of sales and fuel pursuant to ASC 705 rather than as services revenue. To the extent we hold inventory related to these purchases, the related fees previously recorded in services revenue will not be recognized until the inventory is sold. We continue to be principal on the downstream sales of those commodities, which is unchanged from our assessment under previous guidance. The impact on our Consolidated Income Statement and Balance Sheet is as follows (in thousands): Three Months Ended September 30, 2018 Income Statement As Reported Balance Without Adoption of Topic 606 Effect of Change Increase/(Decrease) Commodity sales $ 3,083,625 $ 3,129,947 $ (46,322 ) Services revenue $ 310,265 $ 707,633 $ (397,368 ) Cost of sales and fuel (exclusive of depreciation and operating costs) $ 2,560,765 $ 3,005,767 $ (445,002 ) Depreciation and amortization $ 107,383 $ 107,238 $ 145 Income taxes $ 102,983 $ 102,714 $ 269 Net income $ 313,916 $ 313,018 $ 898 Net income attributable to noncontrolling interests $ 657 $ 655 $ 2 Net income attributable to ONEOK $ 313,259 $ 312,363 $ 896 Nine Months Ended September 30, 2018 Income Statement As Reported Balance Without Adoption of Topic 606 Effect of Change Increase/(Decrease) Commodity sales $ 8,578,891 $ 8,625,213 $ (46,322 ) Services revenue $ 877,605 $ 1,986,563 $ (1,108,958 ) Cost of sales and fuel (exclusive of depreciation and operating costs) $ 7,104,609 $ 8,255,457 $ (1,150,848 ) Depreciation and amortization $ 317,908 $ 317,472 $ 436 Income taxes $ 266,285 $ 267,404 $ (1,119 ) Net income $ 862,144 $ 865,893 $ (3,749 ) Net income attributable to noncontrolling interests $ 3,329 $ 3,322 $ 7 Net income attributable to ONEOK $ 858,815 $ 862,571 $ (3,756 ) September 30, 2018 Balance Sheet As Reported Balance Without Adoption of Topic 606 Effect of Change Increase/(Decrease) Accounts receivable, net $ 1,085,075 $ 1,214,627 $ (129,552 ) Natural gas and natural gas liquids in storage $ 426,293 $ 439,035 $ (12,742 ) Other current assets $ 61,340 $ 60,198 $ 1,142 Property, plant and equipment $ 17,120,187 $ 17,098,053 $ 22,134 Accumulated depreciation and amortization $ 3,159,660 $ 3,157,852 $ 1,808 Other assets $ 191,170 $ 186,417 $ 4,753 Accounts payable $ 1,339,507 $ 1,469,059 $ (129,552 ) Other current liabilities $ 208,312 $ 206,658 $ 1,654 Deferred income taxes $ 132,242 $ 132,859 $ (617 ) Other deferred credits $ 350,400 $ 335,909 $ 14,491 Retained earnings/paid-in capital $ 7,662,673 $ 7,664,722 $ (2,049 ) Revenue Recognition - Revenues are recognized when control of the promised goods or services is transferred to our customers in an amount that reflects the consideration we expect to be entitled to receive in exchange for those goods or services. Our payment terms vary by customer and contract type, including requiring payment before products or services are delivered to certain customers. However, the term between customer prepayments, completion of our performance obligations, invoicing and receipt of payment due is not significant. Practical Expedients - We do not disclose the value of unsatisfied performance obligations for (i) contracts with an original expected length of one year or less and (ii) variable consideration on contracts for which we recognize revenue at the amount to which we have the right to invoice for services performed. Receivables from Customers, Performance Obligations and Revenue Sources - The balances in accounts receivable on our Consolidated Balance Sheet at September 30, 2018, and December 31, 2017, include customer receivables of $1.1 billion and $1.2 billion , respectively. Revenues sources are disaggregated in Note L and are derived from commodity sales and services revenues, as described below: Commodity Sales (all segments) - We contract to deliver residue natural gas, condensate, unfractionated NGLs and/or NGL products to customers at a specified delivery point. Our sales agreements may be daily or longer-term contracts for a specified volume. We consider the sale and delivery of each unit of a commodity an individual performance obligation as the customer is expected to control, accept and benefit from each unit individually. We record revenue when the commodity is delivered to the customer as this represents the point in time when control of the product is transferred to the customer. Revenue is recorded based on the contracted selling price, which is generally index-based and settled monthly. Services Gathering only contracts ( Natural Gas Gathering and Processing segment ) - Under this type of contract, we charge fees for providing midstream services, which include gathering our customer’s natural gas. Our performance obligation begins with delivery of raw natural gas to our system. This service is treated as one performance obligation that is satisfied over time. We use the output method based on delivery of product to our system as the measure of progress, as our services are performed simultaneously. POP contracts with producer take-in-kind rights ( Natural Gas Gathering and Processing segment ) - Under this type of contract, we do not control the stream of unprocessed gas that we receive at the wellhead due to the producer’s take-in-kind rights. We charge fees for providing midstream services, which include gathering and processing our customer’s natural gas. After performing these services, we return a portion of the natural gas to the producer and purchase the remaining commodities. Our performance obligation begins with delivery of raw natural gas to our system. This service is treated as one performance obligation that is satisfied over time. We use the output method based on delivery of product to our system as the measure of progress, as our services are performed simultaneously. Transportation and exchange contracts ( Natural Gas Liquids segment ) - Under this type of contract, we charge fees for providing midstream services, which may include a bundled combination of gathering, transporting and/or fractionation of our customer’s NGLs. Our performance obligation begins with delivery of unfractionated NGLs or NGL products to our system. These services represent a series of distinct services that are treated as one performance obligation that is satisfied over time. We use the output method based on delivery of product to our system as the measure of progress, as our services are performed simultaneously. For transportation services under a tariff on our NGL transportation pipelines, fees are recorded upon redelivery to our customer at the completion of the transportation services. Storage contracts ( Natural Gas Liquids and Natural Gas Pipelines segments ) - We reserve a stated storage capacity and inject/withdraw/store commodities for our customer. The capacity reservation and injection/withdrawal/storage services are considered a bundled service, as we integrate them into one stand-ready obligation provided on a daily basis over the life of the agreement and satisfied over time. Fixed capacity reservation fees are allocated and evenly recognized in revenue. Capacity reservation fees that vary based on a stated or implied economic index and correspond with the costs to provide our services are recognized in revenue based on daily effective fee rate. Transportation, injection and withdrawal fees are recognized in revenue as those services are provided and are dependent on the volume transported, injected or withdrawn by our customer, which is at our customer’s discretion. We use the output method based on the passage of time to measure satisfaction of the performance obligation associated with our daily stand-ready services. Firm service transportation contracts ( Natural Gas Pipelines segment ) - We reserve a stated transportation capacity and transport commodities for our customer. The capacity reservation and transportation services are considered a bundled service, as we integrate them into one stand-ready obligation provided on a daily basis over the life of the agreement and satisfied over time. Fixed capacity reservation fees are allocated and evenly recognized in revenue. Capacity reservation fees that vary based on a stated or implied economic index and correspond with the costs to provide our services are recognized in revenue based on a daily effective fee rate. If the capacity reservation fees vary solely as a contract feature, contract assets or liabilities are recorded for the difference between the amount recorded in revenue and the amount billed to the customer. Transportation fees are recognized in revenue as those services are provided and are dependent on the volume transported by our customer, which is at our customer’s discretion. We use the output method based on the passage of time to measure satisfaction of the performance obligation associated with our daily stand-ready services. Interruptible transportation contracts ( Natural Gas Pipelines segment ) - We agree to transport natural gas on our pipelines between the customer’s specified nomination and delivery points if capacity is available after satisfying firm transportation service obligations. Our performance obligations and those of our customer begin with delivery of natural gas onto our pipeline and is satisfied over time. The transaction price is based on the transportation fees times the volumes transported. These fees may change over time based on an index or other factors provided in the agreement. We use the output method based on delivery of product to the customer to measure satisfaction of the performance obligation. The total consideration for delivered volumes is recorded in revenue at the time of delivery, when the customer obtains control. Contract Assets and Contract Liabilities - Contract assets and contract liabilities are recorded when the amount of revenue recognized from a contract with a customer differs from the amount billed to the customer and recorded in accounts receivable. Our contract asset balances at the beginning and end of the period primarily relate to our firm service transportation contracts with tiered rates. Our contract liabilities primarily represent deferred revenue on NGL storage contracts for which revenue is recognized over a one-year term and deferred revenue on contributions in aid of construction received from customers for which revenue is recognized over the contract period, which averages approximately 10 years. The following tables set forth the changes in our contract asset and contract liability balances during the nine months ended September 30, 2018. Contract Assets ( Millions of dollars ) Balance at January 1, 2018 (a) $ 6.4 Amounts invoiced in excess of revenue recognized (0.7 ) Net additions 2.0 Balance at September 30, 2018 (b) $ 7.7 (a) - Balance includes $0.9 million of current assets. (b) - Contract assets of $2.9 million and $4.8 million are included in other current assets and other assets, respectively, in our Consolidated Balance Sheet. Contract Liabilities ( Millions of dollars ) Balance at January 1, 2018 (a) $ 33.3 Revenue recognized included in beginning balance (19.0 ) Net additions 24.0 Balance at September 30, 2018 (b) $ 38.3 (a) - Balance includes $19.5 million of current liabilities. (b) - Contract liabilities of $23.8 million and $14.5 million are included in other current liabilities and other deferred credits, respectively, in our Consolidated Balance Sheet. Transaction Price Allocated to Unsatisfied Performance Obligations - The following table presents aggregate value allocated to unsatisfied performance obligations as of September 30, 2018, and the amounts we expect to recognize in revenue in future periods, related primarily to firm transportation and storage contracts with remaining contract terms ranging from one month to 26 years: Expected Period of Recognition in Revenue ( Millions of dollars ) Remainder of 2018 $ 90.5 2019 296.2 2020 245.1 2021 237.4 2022 and beyond 1,090.9 Total estimated transaction price allocated to unsatisfied performance obligations $ 1,960.1 The table above excludes variable consideration allocated entirely to wholly unsatisfied performance obligations, wholly unsatisfied promises to transfer distinct goods or services that are part of a single performance obligation and consideration we determine to be fully constrained. Information on the nature of the variable consideration excluded and the nature of the performance obligations to which the variable consideration relates can be found in the description of the major contract types discussed above. The amounts we determined to be fully constrained relate to future sales obligations under long-term sales contracts where the transaction price is not known and minimum volume agreements, which we consider to be fully constrained until invoiced.

SEGMENTS (Notes)

SEGMENTS (Notes)	9 Months Ended
	Sep. 30, 2018
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
SEGMENTS	SEGMENTS Segment Descriptions - Our operations are divided into three reportable business segments, as follows: • our Natural Gas Gathering and Processing segment gathers, treats and processes natural gas; • our Natural Gas Liquids segment gathers, treats, fractionates and transports NGLs and stores, markets and distributes NGL products; and • our Natural Gas Pipelines segment operates regulated interstate and intrastate natural gas transmission pipelines and natural gas storage facilities. Other and eliminations consist of corporate costs, the operating and leasing activities of our headquarters building and related parking facility and eliminations necessary to reconcile our reportable segments to our Consolidated Financial Statements. Accounting Policies - The accounting policies of the segments are described in Note A of the Notes to Consolidated Financial Statements in our Annual Report, updated as described in Note A of this Quarterly Report. Operating Segment Information - The following tables set forth certain selected financial information for our operating segments for the periods indicated: Three Months Ended Natural Gas Natural Gas Natural Gas Total ( Thousands of dollars ) NGL and condensate sales $ 501,163 $ 2,861,896 $ — $ 3,363,059 Residue natural gas sales 245,474 — 763 246,237 Gathering, processing and exchange services revenue 41,101 116,833 — 157,934 Transportation and storage revenue — 45,251 98,031 143,282 Other 3,517 2,308 6,400 12,225 Total revenues (c) 791,255 3,026,288 105,194 3,922,737 Cost of sales and fuel (exclusive of depreciation and operating costs) (542,463 ) (2,544,854 ) (2,384 ) (3,089,701 ) Operating costs (90,970 ) (101,126 ) (36,543 ) (228,639 ) Equity in net earnings from investments 74 16,450 22,789 39,313 Noncash compensation expense and other 1,703 2,268 1,050 5,021 Segment adjusted EBITDA $ 159,599 $ 399,026 $ 90,106 $ 648,731 Depreciation and amortization $ (49,223 ) $ (43,688 ) $ (13,625 ) $ (106,536 ) Capital expenditures $ 213,034 $ 444,780 $ 31,522 $ 689,336 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $316.0 million , of which $276.4 million related to sales within the segment, and cost of sales and fuel of $132.7 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $65.9 million and cost of sales and fuel of $5.5 million . (c) - Intersegment revenues for the Natural Gas Gathering and Processing, Natural Gas Liquids and Natural Gas Pipelines segments totaled $519.7 million , $7.4 million and $2.4 million , respectively. Three Months Ended September 30, 2018 Total Segments Other and Eliminations Total ( Thousands of dollars ) Reconciliations of total segments to consolidated NGL and condensate sales $ 3,363,059 $ (526,398 ) $ 2,836,661 Residue natural gas sales 246,237 — 246,237 Gathering, processing and exchange services revenue 157,934 — 157,934 Transportation and storage revenue 143,282 (2,370 ) 140,912 Other 12,225 (79 ) 12,146 Total revenues (a) $ 3,922,737 $ (528,847 ) $ 3,393,890 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (3,089,701 ) $ 528,936 $ (2,560,765 ) Operating costs $ (228,639 ) $ (1,732 ) $ (230,371 ) Depreciation and amortization $ (106,536 ) $ (847 ) $ (107,383 ) Equity in net earnings from investments $ 39,313 $ — $ 39,313 Capital expenditures $ 689,336 $ 4,967 $ 694,303 (a) - Noncustomer revenue for the three months ended September 30, 2018, totaled $(17.7) million related primarily to losses reclassified from accumulated other comprehensive income from derivatives on commodity contracts. Three Months Ended Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Total ( Thousands of dollars ) Sales to unaffiliated customers $ 453,432 $ 2,348,052 $ 104,340 $ 2,905,824 Intersegment revenues 329,496 153,927 2,098 485,521 Total revenues 782,928 2,501,979 106,438 3,391,345 Cost of sales and fuel (exclusive of depreciation and operating costs) (566,988 ) (2,136,207 ) (10,614 ) (2,713,809 ) Operating costs (79,559 ) (89,803 ) (29,568 ) (198,930 ) Equity in net earnings from investments 3,433 15,287 21,338 40,058 Other 2,136 2,663 (67 ) 4,732 Segment adjusted EBITDA $ 141,950 $ 293,919 $ 87,527 $ 523,396 Depreciation and amortization $ (46,842 ) $ (41,929 ) $ (12,765 ) $ (101,536 ) Impairment of long-lived assets and equity investments $ (20,240 ) $ — $ — $ (20,240 ) Capital expenditures $ 85,542 $ 27,024 $ 18,811 $ 131,377 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $293.1 million , of which $250.2 million related to sales within the segment, and cost of sales and fuel of $124.2 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $65.6 million and cost of sales and fuel of $10.5 million . Three Months Ended September 30, 2017 Total Segments Other and Eliminations Total ( Thousands of dollars ) Reconciliations of total segments to consolidated Sales to unaffiliated customers $ 2,905,824 $ 542 $ 2,906,366 Intersegment revenues 485,521 (485,521 ) — Total revenues $ 3,391,345 $ (484,979 ) $ 2,906,366 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (2,713,809 ) $ 484,393 $ (2,229,416 ) Operating costs $ (198,930 ) $ (5,404 ) $ (204,334 ) Depreciation and amortization $ (101,536 ) $ (762 ) $ (102,298 ) Impairment of long-lived assets and equity investments $ (20,240 ) $ — $ (20,240 ) Equity in net earnings from investments $ 40,058 $ — $ 40,058 Capital expenditures $ 131,377 $ 3,822 $ 135,199 Nine Months Ended Natural Gas Natural Gas Natural Gas Total ( Thousands of dollars ) NGL and condensate sales $ 1,362,159 $ 7,884,183 $ — $ 9,246,342 Residue natural gas sales 709,089 — 5,861 714,950 Gathering, processing and exchange services revenue 122,331 296,561 — 418,892 Transportation and storage revenue — 143,741 289,646 433,387 Other 6,596 8,202 19,390 34,188 Total revenues (c) 2,200,175 8,332,687 314,897 10,847,759 Cost of sales and fuel (exclusive of depreciation and operating costs) (1,478,044 ) (7,009,438 ) (10,475 ) (8,497,957 ) Operating costs (272,931 ) (289,328 ) (104,692 ) (666,951 ) Equity in net earnings from investments 948 49,456 65,666 116,070 Noncash compensation expense and other 6,868 9,789 3,701 20,358 Segment adjusted EBITDA $ 457,016 $ 1,093,166 $ 269,097 $ 1,819,279 Depreciation and amortization $ (145,120 ) $ (128,993 ) $ (41,320 ) $ (315,433 ) Total assets $ 5,811,140 $ 9,632,212 $ 2,109,897 $ 17,553,249 Capital expenditures $ 433,605 $ 786,635 $ 71,897 $ 1,292,137 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $910.3 million , of which $784.8 million related to sales within the segment, and cost of sales and fuel of $379.5 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $198.4 million and cost of sales and fuel of $20.4 million . (c) - Intersegment revenues for the Natural Gas Gathering and Processing, Natural Gas Liquids and Natural Gas Pipelines segments totaled $1,366.0 million , $20.1 million and $7.0 million , respectively. Nine Months Ended September 30, 2018 Total Segments Other and Eliminations Total ( Thousands of dollars ) Reconciliations of total segments to consolidated NGL and condensate sales $ 9,246,342 $ (1,383,864 ) $ 7,862,478 Residue natural gas sales 714,950 (778 ) 714,172 Gathering, processing and exchange services revenue 418,892 (21 ) 418,871 Transportation and storage revenue 433,387 (6,959 ) 426,428 Other 34,188 359 34,547 Total revenues (a) $ 10,847,759 $ (1,391,263 ) $ 9,456,496 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (8,497,957 ) $ 1,393,348 $ (7,104,609 ) Operating costs $ (666,951 ) $ (3,777 ) $ (670,728 ) Depreciation and amortization $ (315,433 ) $ (2,475 ) $ (317,908 ) Equity in net earnings from investments $ 116,070 $ — $ 116,070 Total assets $ 17,553,249 $ 358,065 $ 17,911,314 Capital expenditures $ 1,292,137 $ 17,518 $ 1,309,655 (a) - Noncustomer revenue for the nine months ended September 30, 2018, totaled $(32.1) million related primarily to losses reclassified from accumulated other comprehensive income from derivatives on commodity contracts. Nine Months Ended Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Total ( Thousands of dollars ) Sales to unaffiliated customers $ 1,286,669 $ 6,788,451 $ 305,019 $ 8,380,139 Intersegment revenues 843,350 455,197 6,086 1,304,633 Total revenues 2,130,019 7,243,648 311,105 9,684,772 Cost of sales and fuel (exclusive of depreciation and operating costs) (1,544,263 ) (6,188,501 ) (33,990 ) (7,766,754 ) Operating costs (223,546 ) (255,220 ) (91,813 ) (570,579 ) Equity in net earnings from investments 9,843 44,071 65,071 118,985 Other 2,125 1,459 772 4,356 Segment adjusted EBITDA $ 374,178 $ 845,457 $ 251,145 $ 1,470,780 Depreciation and amortization $ (137,843 ) $ (124,471 ) $ (37,906 ) $ (300,220 ) Impairment of long-lived assets and equity investments $ (20,240 ) $ — $ — $ (20,240 ) Total assets $ 5,385,778 $ 8,515,535 $ 2,040,445 $ 15,941,758 Capital expenditures $ 185,713 $ 59,813 $ 70,671 $ 316,197 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $878.8 million , of which $752.5 million related to sales within the segment, and cost of sales and fuel of $359.6 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $197.3 million and cost of sales and fuel of $32.9 million . Nine Months Ended September 30, 2017 Total Segments Other and Eliminations Total ( Thousands of dollars ) Reconciliations of total segments to consolidated Sales to unaffiliated customers $ 8,380,139 $ 1,610 $ 8,381,749 Intersegment revenues 1,304,633 (1,304,633 ) — Total revenues $ 9,684,772 $ (1,303,023 ) $ 8,381,749 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (7,766,754 ) $ 1,302,473 $ (6,464,281 ) Operating costs $ (570,579 ) $ (38,048 ) $ (608,627 ) Depreciation and amortization $ (300,220 ) $ (2,346 ) $ (302,566 ) Impairment of long-lived assets and equity investments $ (20,240 ) $ — $ (20,240 ) Equity in net earnings from investments $ 118,985 $ — $ 118,985 Total assets $ 15,941,758 $ 823,083 $ 16,764,841 Capital expenditures $ 316,197 $ 14,234 $ 330,431 Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Reconciliation of net income to total segment adjusted EBITDA Net income $ 313,916 $ 166,531 $ 862,144 $ 528,707 Add: Interest expense, net of capitalized interest 121,910 126,533 351,131 361,468 Depreciation and amortization 107,383 102,298 317,908 302,566 Income taxes 102,983 97,128 266,285 195,913 Impairment charges — 20,240 — 20,240 Noncash compensation expense 5,829 4,883 27,195 9,790 Other corporate costs and noncash items (a) (3,290 ) 5,783 (5,384 ) 52,096 Total segment adjusted EBITDA $ 648,731 $ 523,396 $ 1,819,279 $ 1,470,780 (a) - The nine months ended September 30, 2017, includes our April 2017 $20 million contribution of Series E Preferred Stock to the Foundation and costs related to the Merger Transaction of $29.5 million .

SUPPLEMENTAL CONDENSED CONSOLID

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Notes)	9 Months Ended
	Sep. 30, 2018
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Supplemental Condensed Consolidating Financial Information	SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION ONEOK and ONEOK Partners are issuers of certain public debt securities. Effective with the Merger Transaction in 2017, we, ONEOK Partners and the Intermediate Partnership issued, to the extent not already in place, guarantees of the indebtedness of ONEOK and ONEOK Partners. The Intermediate Partnership holds all of ONEOK Partners’ partnership interests and equity in its subsidiaries, as well as a 50 percent interest in Northern Border Pipeline. In lieu of providing separate financial statements for each subsidiary issuer and guarantor, we have included the accompanying condensed consolidating financial statements based on Rule 3-10 of the SEC’s Regulation S-X. We have presented each of the parent and subsidiary issuers in separate columns in this single set of condensed consolidating financial statements. For purposes of the following footnote: • we are referred to as “Parent Issuer and Guarantor”; • ONEOK Partners is referred to as “Subsidiary Issuer and Guarantor”; • the Intermediate Partnership is referred to as “Guarantor Subsidiary”; and • the “Non-Guarantor Subsidiaries” are all subsidiaries other than the Guarantor Subsidiary and Subsidiary Issuer and Guarantor. The following unaudited supplemental condensed consolidating financial information is presented on an equity-method basis reflecting the separate accounts of ONEOK, ONEOK Partners and the Intermediate Partnership, the combined accounts of the Non-Guarantor Subsidiaries, the combined consolidating adjustments and eliminations, and our consolidated amounts for the periods indicated. Condensed Consolidating Statements of Income Three Months Ended September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ — $ 3,083.6 $ — $ 3,083.6 Services — — — 310.8 (0.5 ) 310.3 Total revenues — — — 3,394.4 (0.5 ) 3,393.9 Cost of sales and fuel (exclusive of items shown separately below) — — — 2,560.8 — 2,560.8 Operating expenses 2.0 — — 336.3 (0.5 ) 337.8 Gain on sale of assets — — — (0.2 ) — (0.2 ) Operating income (2.0 ) — — 497.5 — 495.5 Equity in net earnings from investments 457.3 457.1 457.1 30.1 (1,362.3 ) 39.3 Other income (expense), net 9.3 80.3 80.3 (5.3 ) (160.6 ) 4.0 Interest expense, net (49.1 ) (80.3 ) (80.3 ) (72.8 ) 160.6 (121.9 ) Income before income taxes 415.5 457.1 457.1 449.5 (1,362.3 ) 416.9 Income taxes (102.3 ) — — (0.7 ) — (103.0 ) Net income 313.2 457.1 457.1 448.8 (1,362.3 ) 313.9 Less: Net income attributable to noncontrolling interests — — — 0.7 — 0.7 Net income attributable to ONEOK 313.2 457.1 457.1 448.1 (1,362.3 ) 313.2 Less: Preferred stock dividends 0.2 — — — — 0.2 Net income available to common shareholders $ 313.0 $ 457.1 $ 457.1 $ 448.1 $ (1,362.3 ) $ 313.0 Three Months Ended September 30, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ — $ 2,322.5 $ — $ 2,322.5 Services — — — 584.3 (0.5 ) 583.8 Total revenues — — — 2,906.8 (0.5 ) 2,906.3 Cost of sales and fuel (exclusive of items shown separately below) — — — 2,229.4 — 2,229.4 Operating expenses 1.2 — 2.6 303.3 (0.5 ) 306.6 Impairment of long-lived assets — — — 16.0 — 16.0 Gain on sale of assets — — — (0.3 ) — (0.3 ) Operating income (1.2 ) — (2.6 ) 358.4 — 354.6 Equity in net earnings from investments 298.0 298.3 300.9 27.6 (884.7 ) 40.1 Impairment of equity investments — — — (4.3 ) — (4.3 ) Other income (expense), net 4.1 86.1 86.1 (4.3 ) (172.2 ) (0.2 ) Interest expense, net (43.2 ) (86.1 ) (86.1 ) (83.3 ) 172.2 (126.5 ) Income before income taxes 257.7 298.3 298.3 294.1 (884.7 ) 263.7 Income taxes (91.9 ) — — (5.3 ) — (97.2 ) Net income 165.8 298.3 298.3 288.8 (884.7 ) 166.5 Less: Net income attributable to noncontrolling interests 0.1 — — 0.7 — 0.8 Net income attributable to ONEOK 165.7 298.3 298.3 288.1 (884.7 ) 165.7 Less: Preferred stock dividends 0.2 — — — — 0.2 Net income available to common shareholders $ 165.5 $ 298.3 $ 298.3 $ 288.1 $ (884.7 ) $ 165.5 Nine Months Ended September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ — $ 8,578.9 $ — $ 8,578.9 Services — — — 879.1 (1.5 ) 877.6 Total revenues — — — 9,458.0 (1.5 ) 9,456.5 Cost of sales and fuel (exclusive of items shown separately below) — — — 7,104.6 — 7,104.6 Operating expenses 3.3 — — 986.8 (1.5 ) 988.6 Gain on sale of assets — — — (0.3 ) — (0.3 ) Operating income (3.3 ) — — 1,366.9 — 1,363.6 Equity in net earnings from investments 1,226.6 1,231.2 1,231.2 86.2 (3,659.1 ) 116.1 Other income (expense), net 23.1 234.9 234.9 (23.3 ) (469.8 ) (0.2 ) Interest expense, net (129.2 ) (234.9 ) (234.9 ) (221.9 ) 469.8 (351.1 ) Income before income taxes 1,117.2 1,231.2 1,231.2 1,207.9 (3,659.1 ) 1,128.4 Income taxes (258.4 ) — — (7.9 ) — (266.3 ) Net income 858.8 1,231.2 1,231.2 1,200.0 (3,659.1 ) 862.1 Less: Net income attributable to noncontrolling interests — — — 3.3 — 3.3 Net income attributable to ONEOK 858.8 1,231.2 1,231.2 1,196.7 (3,659.1 ) 858.8 Less: Preferred stock dividends 0.8 — — — — 0.8 Net income available to common shareholders $ 858.0 $ 1,231.2 $ 1,231.2 $ 1,196.7 $ (3,659.1 ) $ 858.0 Nine Months Ended September 30, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ — $ 6,700.3 $ — $ 6,700.3 Services — — — 1,683.0 (1.5 ) 1,681.5 Total revenues — — — 8,383.3 (1.5 ) 8,381.8 Cost of sales and fuel (exclusive of items shown separately below) — — — 6,464.3 — 6,464.3 Operating expenses 25.9 — 8.8 878.0 (1.5 ) 911.2 Impairment of long-lived assets — — — 16.0 — 16.0 Gain on sale of assets — — — (0.9 ) — (0.9 ) Operating income (25.9 ) — (8.8 ) 1,025.9 — 991.2 Equity in net earnings from investments 842.0 845.9 854.7 72.1 (2,495.7 ) 119.0 Impairment of equity investments — — — (4.3 ) — (4.3 ) Other income (expense), net (15.5 ) 272.2 272.2 (4.3 ) (544.4 ) (19.8 ) Interest expense, net (93.5 ) (272.2 ) (272.2 ) (268.0 ) 544.4 (361.5 ) Income before income taxes 707.1 845.9 845.9 821.4 (2,495.7 ) 724.6 Income taxes (180.9 ) — — (15.0 ) — (195.9 ) Net income 526.2 845.9 845.9 806.4 (2,495.7 ) 528.7 Less: Net income attributable to noncontrolling interests 201.4 — — 2.5 — 203.9 Net income attributable to ONEOK 324.8 845.9 845.9 803.9 (2,495.7 ) 324.8 Less: Preferred stock dividends 0.5 — — — — 0.5 Net income available to common shareholders $ 324.3 $ 845.9 $ 845.9 $ 803.9 $ (2,495.7 ) $ 324.3 Condensed Consolidating Statements of Comprehensive Income Three Months Ended September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 313.2 $ 457.1 $ 457.1 $ 448.8 $ (1,362.3 ) $ 313.9 Other comprehensive income (loss), net of tax Unrealized gains (losses) on derivatives, net of tax 20.2 (30.7 ) (30.7 ) (23.7 ) 61.4 (3.5 ) Realized (gains) losses on derivatives in net income, net of tax — 25.0 20.6 14.9 (41.2 ) 19.3 Change in pension and postretirement benefit plan liability, net of tax 3.2 — — — — 3.2 Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax — 2.0 2.0 1.5 (4.0 ) 1.5 Total other comprehensive income (loss), net of tax 23.4 (3.7 ) (8.1 ) (7.3 ) 16.2 20.5 Comprehensive income 336.6 453.4 449.0 441.5 (1,346.1 ) 334.4 Less: Comprehensive income attributable to noncontrolling interests — — — 0.7 — 0.7 Comprehensive income attributable to ONEOK $ 336.6 $ 453.4 $ 449.0 $ 440.8 $ (1,346.1 ) $ 333.7 Three Months Ended September 30, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 165.8 $ 298.3 $ 298.3 $ 288.8 $ (884.7 ) $ 166.5 Other comprehensive income (loss), net of tax Unrealized gains (losses) on derivatives, net of tax 18.4 (61.9 ) (42.4 ) (19.5 ) 84.8 (20.6 ) Realized (gains) losses on derivatives in net income, net of tax 0.6 19.8 15.9 8.6 (31.8 ) 13.1 Change in pension and postretirement benefit plan liability, net of tax 2.0 — — — — 2.0 Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax — (0.3 ) (0.3 ) (0.2 ) 0.6 (0.2 ) Total other comprehensive income (loss), net of tax 21.0 (42.4 ) (26.8 ) (11.1 ) 53.6 (5.7 ) Comprehensive income 186.8 255.9 271.5 277.7 (831.1 ) 160.8 Less: Comprehensive income attributable to noncontrolling interests — — — 0.7 — 0.7 Comprehensive income attributable to ONEOK $ 186.8 $ 255.9 $ 271.5 $ 277.0 $ (831.1 ) $ 160.1 Nine Months Ended September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 858.8 $ 1,231.2 $ 1,231.2 $ 1,200.0 $ (3,659.1 ) $ 862.1 Other comprehensive income (loss), net of tax Unrealized gains (losses) on derivatives, net of tax 54.0 (56.2 ) (56.2 ) (43.3 ) 112.4 10.7 Realized (gains) losses on derivatives in net income, net of tax 1.9 53.9 42.4 30.0 (84.8 ) 43.4 Change in pension and postretirement benefit plan liability, net of tax 9.7 (0.6 ) — — — 9.1 Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax — 6.9 6.9 5.3 (13.8 ) 5.3 Total other comprehensive income (loss), net of tax 65.6 4.0 (6.9 ) (8.0 ) 13.8 68.5 Comprehensive income 924.4 1,235.2 1,224.3 1,192.0 (3,645.3 ) 930.6 Less: Comprehensive income attributable to noncontrolling interests — — — 3.3 — 3.3 Comprehensive income attributable to ONEOK $ 924.4 $ 1,235.2 $ 1,224.3 $ 1,188.7 $ (3,645.3 ) $ 927.3 Nine Months Ended September 30, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 526.2 $ 845.9 $ 845.9 $ 806.4 $ (2,495.7 ) $ 528.7 Other comprehensive income (loss), net of tax Unrealized gains (losses) on derivatives, net of tax 18.1 (38.8 ) (6.1 ) 13.3 12.2 (1.3 ) Realized (gains) losses on derivatives in net income, net of tax 1.6 50.7 38.0 26.0 (76.0 ) 40.3 Change in pension and postretirement benefit plan liability, net of tax 6.1 — — — — 6.1 Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax — (1.5 ) (1.5 ) (1.2 ) 3.0 (1.2 ) Total other comprehensive income (loss), net of tax 25.8 10.4 30.4 38.1 (60.8 ) 43.9 Comprehensive income 552.0 856.3 876.3 844.5 (2,556.5 ) 572.6 Less: Comprehensive income attributable to noncontrolling interests 232.4 — — 2.5 — 234.9 Comprehensive income attributable to ONEOK $ 319.6 $ 856.3 $ 876.3 $ 842.0 $ (2,556.5 ) $ 337.7 Condensed Consolidating Balance Sheets September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total Assets ( Millions of dollars ) Current assets Cash and cash equivalents $ 84.5 $ — $ — $ — $ — $ 84.5 Accounts receivable, net — — — 1,085.1 — 1,085.1 Materials and supplies — — — 128.6 — 128.6 Natural gas and natural gas liquids in storage — — — 426.3 — 426.3 Other current assets 10.4 — — 73.0 — 83.4 Total current assets 94.9 — — 1,713.0 — 1,807.9 Property, plant and equipment Property, plant and equipment 141.0 — — 16,979.2 — 17,120.2 Accumulated depreciation and amortization 90.5 — — 3,069.2 — 3,159.7 Net property, plant and equipment 50.5 — — 13,910.0 — 13,960.5 Investments and other assets Investments 5,977.5 3,359.0 9,223.2 796.8 (18,374.9 ) 981.6 Intercompany notes receivable 4,769.1 7,682.5 1,818.3 — (14,269.9 ) — Other assets 174.3 — — 988.2 (1.2 ) 1,161.3 Total investments and other assets 10,920.9 11,041.5 11,041.5 1,785.0 (32,646.0 ) 2,142.9 Total assets $ 11,066.3 $ 11,041.5 $ 11,041.5 $ 17,408.0 $ (32,646.0 ) $ 17,911.3 Liabilities and equity Current liabilities Current maturities of long-term debt $ — $ 500.0 $ — $ 7.7 $ — $ 507.7 Short-term borrowings 120.0 — — — — 120.0 Accounts payable 5.1 — — 1,334.4 — 1,339.5 Other current liabilities 71.8 67.6 — 343.6 — 483.0 Total current liabilities 196.9 567.6 — 1,685.7 — 2,450.2 Intercompany debt — — 7,682.5 6,587.4 (14,269.9 ) — Long-term debt, excluding current maturities 3,962.2 4,340.4 — 23.1 — 8,325.7 Deferred credits and other liabilities Deferred income taxes 25.8 — — 107.6 (1.2 ) 132.2 Other deferred credits 228.6 — — 121.8 — 350.4 Total deferred credits and other liabilities 254.4 — — 229.4 (1.2 ) 482.6 Commitments and contingencies Equity 6,652.8 6,133.5 3,359.0 8,882.4 (18,374.9 ) 6,652.8 Total liabilities and equity $ 11,066.3 $ 11,041.5 $ 11,041.5 $ 17,408.0 $ (32,646.0 ) $ 17,911.3 December 31, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total Assets ( Millions of dollars ) Current assets Cash and cash equivalents $ 37.2 $ — $ — $ — $ — $ 37.2 Accounts receivable, net — — — 1,203.0 — 1,203.0 Materials and supplies — — — 90.3 — 90.3 Natural gas and natural gas liquids in storage — — — 342.3 — 342.3 Other current assets 9.8 1.3 — 80.6 — 91.7 Total current assets 47.0 1.3 — 1,716.2 — 1,764.5 Property, plant and equipment Property, plant and equipment 128.3 — — 15,431.3 — 15,559.6 Accumulated depreciation and amortization 86.4 — — 2,775.1 — 2,861.5 Net property, plant and equipment 41.9 — — 12,656.2 — 12,698.1 Investments and other assets Investments 5,752.1 3,133.7 8,058.4 803.0 (16,744.0 ) 1,003.2 Intercompany notes receivable 2,926.9 8,627.8 3,703.1 — (15,257.8 ) — Other assets 416.9 0.2 — 1,007.4 (44.4 ) 1,380.1 Total investments and other assets 9,095.9 11,761.7 11,761.5 1,810.4 (32,046.2 ) 2,383.3 Total assets $ 9,184.8 $ 11,763.0 $ 11,761.5 $ 16,182.8 $ (32,046.2 ) $ 16,845.9 Liabilities and equity Current liabilities Current maturities of long-term debt $ — $ 425.0 $ — $ 7.7 $ — $ 432.7 Short-term borrowings 614.7 — — — — 614.7 Accounts payable 12.0 — — 1,128.6 — 1,140.6 Other current liabilities 65.9 85.0 — 328.4 — 479.3 Total current liabilities 692.6 510.0 — 1,464.7 — 2,667.3 Intercompany debt — — 8,627.8 6,630.0 (15,257.8 ) — Long-term debt, excluding current maturities 2,726.4 5,336.4 — 28.8 — 8,091.6 Deferred credits and other liabilities Deferred income taxes — — — 97.1 (44.4 ) 52.7 Other deferred credits 237.9 — — 111.0 — 348.9 Total deferred credits and other liabilities 237.9 — — 208.1 (44.4 ) 401.6 Commitments and contingencies Equity Equity excluding noncontrolling interests in consolidated subsidiaries 5,527.9 5,916.6 3,133.7 7,693.7 (16,744.0 ) 5,527.9 Noncontrolling interests in consolidated subsidiaries — — — 157.5 — 157.5 Total equity 5,527.9 5,916.6 3,133.7 7,851.2 (16,744.0 ) 5,685.4 Total liabilities and equity $ 9,184.8 $ 11,763.0 $ 11,761.5 $ 16,182.8 $ (32,046.2 ) $ 16,845.9 Condensed Consolidating Statements of Cash Flows Nine Months Ended September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Operating activities Cash provided by operating activities $ 964.4 $ 993.8 $ 48.9 $ 1,507.4 $ (1,998.0 ) $ 1,516.5 Investing activities Capital expenditures (15.0 ) — — (1,294.7 ) — (1,309.7 ) Cash paid for acquisition (195.0 ) — — — — (195.0 ) Contributions to unconsolidated affiliates — — (0.5 ) (0.3 ) — (0.8 ) Other investing activities — — 10.8 9.9 — 20.7 Cash provided by (used in) investing activities (210.0 ) — 10.3 (1,285.1 ) — (1,484.8 ) Financing activities Dividends paid (983.1 ) (999.0 ) (999.0 ) — 1,998.0 (983.1 ) Distributions to noncontrolling interests — — — (3.5 ) — (3.5 ) Intercompany borrowings (advances), net (1,640.5 ) 930.2 939.8 (229.5 ) — — Borrowing (repayment) of short-term borrowings, net (494.7 ) — — — — (494.7 ) Issuance of long-term debt, net of discounts 1,245.8 — — — — 1,245.8 Repayment of long-term debt — (925.0 ) — (5.7 ) — (930.7 ) Issuance of common stock 1,195.1 — — — — 1,195.1 Other, net (29.7 ) — — 16.4 — (13.3 ) Cash provided by (used in) financing activities (707.1 ) (993.8 ) (59.2 ) — (222.3 ) 1,998.0 15.6 Change in cash and cash equivalents 47.3 — — — — 47.3 Cash and cash equivalents at beginning of period 37.2 — — — — 37.2 Cash and cash equivalents at end of period $ 84.5 $ — $ — $ — $ — $ 84.5 Nine Months Ended September 30, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Operating activities Cash provided by operating activities $ 620.8 $ 994.3 $ 42.1 $ 1,005.8 $ (1,727.0 ) $ 936.0 Investing activities Capital expenditures (0.5 ) — — (329.9 ) — (330.4 ) Contributions to unconsolidated affiliates — — (83.0 ) (4.7 ) — (87.7 ) Other investing activities — — 11.2 12.3 — 23.5 Cash used in investing activities (0.5 ) — (71.8 ) (322.3 ) — (394.6 ) Financing activities Dividends paid (543.4 ) (999.0 ) (999.0 ) — 1,998.0 (543.4 ) Distributions to noncontrolling interests — — — (4.1 ) (271.0 ) (275.1 ) Intercompany borrowings (advances), net (2,376.9 ) 2,022.2 1,028.3 (673.6 ) — — Borrowing (repayment) of short-term borrowings, net 932.3 (1,110.3 ) — — — (178.0 ) Issuance of long-term debt, net of discounts 1,190.1 — — — — 1,190.1 Repayment of long-term debt (87.1 ) (900.0 ) — (5.8 ) — (992.9 ) Issuance of common stock 45.8 — — — — 45.8 Other, net (17.9 ) (7.2 ) — — — (25.1 ) Cash provided by (used in) financing activities (857.1 ) (994.3 ) 29.3 (683.5 ) 1,727.0 (778.6 ) Change in cash and cash equivalents (236.8 ) — (0.4 ) — — (237.2 ) Cash and cash equivalents at beginning of period 248.5 — 0.4 — — 248.9 Cash and cash equivalents at end of period $ 11.7 $ — $ — $ — $ — $ 11.7

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Basis of Accounting, Policy [Policy Text Block]	Our accompanying unaudited consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC. These statements have been prepared in accordance with GAAP and reflect all adjustments that, in our opinion, are necessary for a fair statement of the results for the interim periods presented. All such adjustments are of a normal recurring nature. The 2017 year-end Consolidated Balance Sheet data was derived from our audited financial statements but does not include all disclosures required by GAAP. Certain reclassifications have been made in the prior-year financial statements to conform to the current year presentation. These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements in our Annual Report.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Standards Update - Changes to GAAP are established by the Financial Accounting Standards Board (FASB) in the form of ASUs to the FASB Accounting Standards Codification. We consider the applicability and impact of all ASUs. ASUs not listed below were assessed and determined to be either not applicable or clarifications of ASUs listed below. We also exclude ASUs not yet adopted that were disclosed in our Annual Report to not materially impact us. The following tables provide a brief description of recent accounting pronouncements and our analysis of the effects on our financial statements: Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standards that were adopted ASU 2014-09, “Revenue from Contracts with Customers (Topic 606)” The standard outlines the principles an entity must apply to measure and recognize revenue for entities that enter into contracts to provide goods or services to their customers. The core principle is that an entity should recognize revenue at an amount that reflects the consideration to which the entity expects to be entitled in exchange for transferring goods or services to a customer. The amendment also requires more extensive disaggregated revenue disclosures in interim and annual financial statements. First quarter 2018 We adopted this standard on January 1, 2018, using the modified retrospective method. We recognized the cumulative effect of adopting the new revenue standard as an increase to beginning retained earnings of $1.7 million. Results for reporting periods beginning after January 1, 2018, are presented under the new standard, while prior periods are not adjusted and continue to be reported under the accounting standards in effect for those periods. The adoption of Topic 606 was not material to our net income; however, a significant portion of amounts historically presented as services revenues are now presented as a reduction to cost of sales and fuel. See Note K for discussion of these changes and additional disclosures. Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standards that were adopted ( continued ) ASU 2016-01, “Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities” The standard requires all equity investments, other than those accounted for using the equity method of accounting or those that result in consolidation of the investee, to be measured at fair value with changes in fair value recognized in net income, eliminates the available-for-sale classification for equity securities with readily determinable fair values and eliminates the cost method for equity investments without readily determinable fair values. First quarter 2018 We do not have any equity investments classified as available-for-sale or accounted for using the cost method; therefore, the impact of adopting of this standard was not material. ASU 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments” The standard clarifies the classification of certain cash receipts and cash payments on the statement of cash flows where diversity in practice has been identified. First quarter 2018 The impact of adopting this standard was not material. ASU 2017-07, “Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost” The standard requires the service cost component of net benefit cost to be reported in the same line item or items as other compensation costs from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations. First quarter 2018 We adopted this standard on January 1, 2018, and utilized the practical expedient to estimate the impact on the prior comparative period information presented. Immaterial reclassifications have been made to prior comparative period information to reflect the current period presentation. Prior to adoption, we expensed all components of the net periodic benefit costs for our pension and postretirement benefit plans in operations and maintenance expense. We now record only the service component of the net periodic benefit costs in operations and maintenance expense, with the remainder being recorded in other expense. There was no change to net income from the adoption of this standard. ASU 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities” The standard more closely aligns hedge accounting with companies’ existing risk-management strategies by expanding the strategies eligible for hedge accounting, relaxing the timing requirements of hedge documentation and effectiveness assessments, permitting in certain cases, the use of qualitative assessments on an ongoing basis to assess hedge effectiveness, and requiring new disclosures and presentation. First quarter 2018 We adopted this standard in the first quarter 2018 and recorded an immaterial cumulative-effect adjustment to the opening balance of retained earnings and other comprehensive income to eliminate the separate measurement of hedge ineffectiveness. See Note C for changes to disclosures due to adopting this standard. ASU 2018-02, “Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” This standard allows a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. First quarter 2018 We adopted this standard in the first quarter 2018 and recorded a $38.1 million adjustment to retained earnings and accumulated other comprehensive income to eliminate the stranded tax effects resulting from the Tax Cuts and Jobs Act. Standard Description Date of Adoption Effect on the Financial Statements or Other Significant Matters Standards that are not yet adopted ASU 2016-02, “Leases (Topic 842)” The standard requires the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases under previous GAAP. It also requires qualitative disclosures along with specific quantitative disclosures by lessees and lessors to meet the objective of enabling users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. First quarter 2019 We are evaluating our current leases and other contracts that may be considered leases under the new standard and the impact on our internal controls, accounting policies and financial statements and disclosures. We have developed a database of our existing leases, and we have implemented accounting software to facilitate compliance with this standard. We are developing internal controls designed to ensure the completeness and accuracy of the data. Upon adoption of Topic 842, we expect to recognize right of use assets and lease liabilities not previously recorded on our Consolidated Balance Sheets and provide required footnote disclosures. We do not expect the impact of adopting this standard to be material to our Consolidated Financial Statements. We expect to elect the transition practical expedient, which allows us to not evaluate land easements that existed prior to January 1, 2019, and the optional transition method to record the adoption impact through a cumulative adjustment to equity. ASU 2018-07, “Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting” The standard aligns the measurement and classification guidance for share-based payments to nonemployees with the guidance for share-based payments to employees, with certain exceptions. First quarter 2019 We do not expect the adoption of this standard to materially impact us. ASU 2018-13, “Fair Value Measurement (Topic 820)” The standard modifies certain disclosure requirements for fair value measurements in Topic 820. First quarter 2020 We are evaluating the impact of this standard on us. ASU 2018-14, “Compensation - Retirement Benefits - Defined Benefit Plans - General (Topic 715-20)” The standard modifies the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. First quarter 2021 We are evaluating the impact of this standard on us.
Goodwill and Intangible Assets, Policy [Policy Text Block]	Goodwill Impairment Review - We assess our goodwill for impairment at least annually as of July 1. At July 1, 2018, we assessed qualitative factors to determine whether it was more likely than not that the fair value of each of our reporting units was less than its carrying amount. After assessing qualitative factors (including macroeconomic conditions, industry and market considerations, cost factors and overall financial performance), we determined that it was more likely than not that the fair value of each reporting unit was greater than its respective carrying value, that no further testing was necessary and that goodwill was not considered impaired.

FAIR VALUE MEASUREMENTS FAIR VA

FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS (Policies)	9 Months Ended
	Sep. 30, 2018
Fair Value Accounting Policy [Abstract]
Fair Value of Financial Instruments, Policy [Policy Text Block]	Determining Fair Value - We define fair value as the price that would be received from the sale of an asset or the transfer of a liability in an orderly transaction between market participants at the measurement date. We use market and income approaches to determine the fair value of our assets and liabilities and consider the markets in which the transactions are executed. We measure the fair value of a group of financial assets and liabilities consistent with how a market participant would price the net risk exposure at the measurement date. While many of the contracts in our derivative portfolio are executed in liquid markets where price transparency exists, some contracts are executed in markets for which market prices may exist, but the market may be relatively inactive. This results in limited price transparency that requires management’s judgment and assumptions to estimate fair values. For certain transactions, we utilize modeling techniques using NYMEX-settled pricing data and implied forward LIBOR curves. Inputs into our fair value estimates include commodity-exchange prices, over-the-counter quotes, historical correlations of pricing data, data obtained from third-party pricing services and LIBOR and other liquid money-market instrument rates. We validate our valuation inputs with third-party information and settlement prices from other sources, where available. In addition, as prescribed by the income approach, we compute the fair value of our derivative portfolio by discounting the projected future cash flows from our derivative assets and liabilities to present value using interest-rate yields to calculate present-value discount factors derived from LIBOR, Eurodollar futures and the LIBOR interest-rate swaps market. We also contemplate the potential impact on market prices of liquidating positions in an orderly manner over a reasonable period of time under current market conditions. We consider current market data in evaluating counterparties’, as well as our own, nonperformance risk, net of collateral, by using specific and sector bond yields and monitoring the credit default swap markets. Although we use our best estimates to determine the fair value of the derivative contracts we have executed, the ultimate market prices realized could differ materially from our estimates. The fair value of our forward-starting interest-rate swaps are determined using financial models that incorporate the implied forward LIBOR yield curve for the same period as the future interest-rate swap settlements. Fair Value Hierarchy - At each balance sheet date, we utilize a fair value hierarchy to classify fair value amounts recognized or disclosed in our financial statements based on the observability of inputs used to estimate such fair value. The levels of the hierarchy are described below: • Level 1 - fair value measurements are based on unadjusted quoted prices for identical securities in active markets, including NYMEX-settled prices. These balances are composed predominantly of exchange-traded derivative contracts for natural gas and crude oil. • Level 2 - fair value measurements are based on significant observable pricing inputs, such as NYMEX-settled prices for natural gas and crude oil, and financial models that utilize implied forward LIBOR yield curves for interest-rate swaps. • Level 3 - fair value measurements are based on inputs that may include one or more unobservable inputs, including internally developed natural gas basis and NGL price curves that incorporate observable and unobservable market data from broker quotes, third-party pricing services, market volatilities derived from the most recent NYMEX close spot prices and forward LIBOR curves, and adjustments for the credit risk of our counterparties. We corroborate the data on which our fair value estimates are based using our market knowledge of recent transactions, analysis of historical correlations and validation with independent broker quotes. These balances categorized as Level 3 are composed of derivatives for natural gas and NGLs. We do not believe that our Level 3 fair value estimates have a material impact on our results of operations, as the majority of our derivatives are accounted for as hedges. Determining the appropriate fair value measurement classification within the fair value hierarchy requires management’s judgment regarding the degree to which market data is observable or corroborated by observable market data. We categorize derivatives for which fair value is determined using multiple inputs within a single level, based on the lowest level input that is significant to the fair value measurement in its entirety.

EQUITY (Policies)

EQUITY (Policies)	6 Months Ended
	Jun. 30, 2017
Equity [Abstract]
Partnership agreement	Cash Distributions - Prior to the consummation of the Merger Transaction, we received distributions from ONEOK Partners on our common and Class B units and our 2 percent general partner interest, which included our incentive distribution rights.

SEGMENTS SEGMENTS (Policies)

SEGMENTS SEGMENTS (Policies)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Segment Accounting Policy [Policy Text Block]	Accounting Policies - The accounting policies of the segments are described in Note A of the Notes to Consolidated Financial Statements in our Annual Report, updated as described in Note A of this Quarterly Report.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Recurring Fair Value Measurements	The following tables set forth our recurring fair value measurements for the periods indicated: September 30, 2018 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 183 $ — $ 53,946 $ 54,129 $ (54,129 ) $ — Interest-rate contracts — 50,509 — 50,509 — 50,509 Total derivative assets $ 183 $ 50,509 $ 53,946 $ 104,638 $ (54,129 ) $ 50,509 Derivative liabilities Commodity contracts Financial contracts $ (17,337 ) $ — $ (83,013 ) $ (100,350 ) $ 100,350 $ — Physical contracts — — (2,010 ) (2,010 ) — (2,010 ) Total derivative liabilities $ (17,337 ) $ — $ (85,023 ) $ (102,360 ) $ 100,350 $ (2,010 ) (a) - Derivative assets and liabilities are presented in our Consolidated Balance Sheets on a net basis. We net derivative assets and liabilities when a legally enforceable master-netting arrangement exists between the counterparty to a derivative contract and us. At September 30, 2018 , we held no cash and posted $67.8 million of cash with various counterparties, including $46.2 million of cash collateral that is offsetting derivative net liability positions under master-netting arrangements in the table above. The remaining $21.6 million of cash collateral in excess of derivative net liability positions is included in other current assets in our Consolidated Balance Sheets. December 31, 2017 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 4,252 $ — $ 20,203 $ 24,455 $ (24,455 ) $ — Interest rate contracts — 49,960 — 49,960 — 49,960 Total derivative assets $ 4,252 $ 49,960 $ 20,203 $ 74,415 $ (24,455 ) $ 49,960 Derivative liabilities Commodity contracts Financial contracts $ (5,708 ) $ — $ (48,260 ) $ (53,968 ) $ 53,936 $ (32 ) Physical contracts — — (4,781 ) (4,781 ) — (4,781 ) Total derivative liabilities $ (5,708 ) $ — $ (53,041 ) $ (58,749 ) $ 53,936 $ (4,813 ) (a) - Derivative assets and liabilities are presented in our Consolidated Balance Sheets on a net basis. We net derivative assets and liabilities when a legally enforceable master-netting arrangement exists between the counterparty to a derivative contract and us. At December 31, 2017 , we held no cash and posted $49.7 million of cash with various counterparties, including $29.5 million of cash collateral that is offsetting derivative net liability positions under master-netting arrangements in the table above. The remaining $20.2 million of cash collateral in excess of derivative net liability positions is included in other current assets in our Consolidated Balance Sheets.
Reconciliation of Level 3 Fair Value Measurements	The following table sets forth a reconciliation of our Level 3 fair value measurements for the periods indicated: Three Months Ended Nine Months Ended September 30, September 30, Derivative Assets (Liabilities) 2018 2017 2018 2017 ( Thousands of dollars ) Net assets (liabilities) at beginning of period $ (23,501 ) $ 750 $ (32,838 ) $ (23,319 ) Total realized/unrealized gains (losses): Included in earnings (a) (22 ) (675 ) (122 ) (417 ) Included in other comprehensive income (loss) (7,554 ) (26,581 ) 1,883 (2,770 ) Net assets (liabilities) at end of period $ (31,077 ) $ (26,506 ) $ (31,077 ) $ (26,506 ) (a) - Included in commodity sales revenues in our Consolidated Statements of Income.

RISK MANAGEMENT AND HEDGING A_2

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES (Tables)	9 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivatives	The following table sets forth the fair values of our derivative instruments presented on a gross basis for the periods indicated: September 30, 2018 December 31, 2017 Location in our Consolidated Balance Sheets Assets (Liabilities) Assets (Liabilities) ( Thousands of dollars ) Derivatives designated as hedging instruments Commodity contracts Financial contracts Other current assets/other current liabilities $ 46,411 $ (84,174 ) $ 16,978 $ (42,819 ) Other assets/other deferred credits 3,461 (11,938 ) — (3,838 ) Physical contracts Other current liabilities — (1,898 ) — (4,781 ) Other deferred credits — (112 ) — — Interest-rate contracts Other current assets — — 1,330 — Other assets 50,509 — 48,630 — Total derivatives designated as hedging instruments 100,381 (98,122 ) 66,938 (51,438 ) Derivatives not designated as hedging instruments Commodity contracts Financial contracts Other current assets/other current liabilities 4,257 (4,238 ) 7,477 (7,311 ) Total derivatives not designated as hedging instruments 4,257 (4,238 ) 7,477 (7,311 ) Total derivatives $ 104,638 $ (102,360 ) $ 74,415 $ (58,749 )
Notional Amounts of Derivative Instruments	The following table sets forth the notional quantities for derivative instruments held for the periods indicated: September 30, 2018 December 31, 2017 Contract Type Purchased/ Payor Sold/ Receiver Purchased/ Payor Sold/ Receiver Derivatives designated as hedging instruments: Cash flow hedges Fixed price - Natural gas ( Bcf ) Futures and swaps — (36.1 ) — (24.5 ) - Crude oil and NGLs ( MMBbl ) Futures, forwards and swaps 7.2 (16.5 ) 3.5 (11.1 ) Basis - Natural gas ( Bcf ) Futures and swaps — (36.1 ) — (24.5 ) Interest-rate contracts ( Millions of dollars ) Swaps $ 1,750.0 $ — $ 1,750.0 $ — Derivatives not designated as hedging instruments: Fixed price - NGLs ( MMBbl ) Futures, forwards and swaps 0.2 (0.2 ) 0.8 (0.8 )
Schedule of Cash Flow Hedging Instruments Effect on Comprehensive Income (Loss)	The following table sets forth the unrealized effect of cash flow hedges recognized in other comprehensive income (loss) for the periods indicated: Three Months Ended Nine Months Ended Derivatives in Cash Flow Hedging Relationships September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Commodity contracts $ (30,783 ) $ (42,450 ) $ (56,246 ) $ (6,123 ) Interest-rate contracts 26,203 9,613 70,179 (3,853 ) Total unrealized gain (loss) recognized in other comprehensive income (loss) on derivatives $ (4,580 ) $ (32,837 ) $ 13,933 $ (9,976 )
Schedule of Cash Flow Hedging Instruments Effect on Income	The following table sets forth the effect of cash flow hedges in our Consolidated Statements of Income for the periods indicated: Derivatives in Cash Flow Hedging Relationships Location of Gain (Loss) Reclassified from Accumulated Other Comprehensive Loss into Net Income Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Commodity contracts Commodity sales revenues $ (20,630 ) $ (15,913 ) $ (42,430 ) $ (38,028 ) Interest-rate contracts Interest expense (4,383 ) (4,820 ) (13,929 ) (15,321 ) Total gain (loss) reclassified from accumulated other comprehensive loss into net income on derivatives $ (25,013 ) $ (20,733 ) $ (56,359 ) $ (53,349 )

DEBT DEBT (Tables)

DEBT DEBT (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Instrument [Line Items]
Debt [Table Text Block]	The following table sets forth our consolidated debt for the periods indicated: September 30, December 31, ( Thousands of dollars ) Commercial paper outstanding, bearing a weighted-average interest rate of 2.85% and 2.23% as of September 30, 2018, and December 31, 2017, respectively. $ 120,000 $ 614,673 Senior unsecured obligations: $425,000 at 3.2% due September 2018 — 425,000 $1,000,000 term loan, rate of 2.87% as of December 31, 2017, due January 2019 — 500,000 $500,000 at 8.625% due March 2019 500,000 500,000 $300,000 at 3.8% due March 2020 300,000 300,000 $700,000 at 4.25% due February 2022 547,397 547,397 $900,000 at 3.375 % due October 2022 900,000 900,000 $425,000 at 5.0 % due September 2023 425,000 425,000 $500,000 at 7.5% due September 2023 500,000 500,000 $500,000 at 4.9 % due March 2025 500,000 500,000 $500,000 at 4.0% due July 2027 500,000 500,000 $800,000 at 4.55% due July 2028 800,000 — $100,000 at 6.875% due September 2028 100,000 100,000 $400,000 at 6.0% due June 2035 400,000 400,000 $600,000 at 6.65% due October 2036 600,000 600,000 $600,000 at 6.85% due October 2037 600,000 600,000 $650,000 at 6.125% due February 2041 650,000 650,000 $400,000 at 6.2% due September 2043 400,000 400,000 $700,000 at 4.95% due July 2047 700,000 700,000 $450,000 at 5.2% due July 2048 450,000 — Guardian Pipeline Weighted average 7.85% due December 2022 30,870 36,607 Total debt 9,023,267 9,198,677 Unamortized portion of terminated swaps 17,179 18,468 Unamortized debt issuance costs and discounts (87,088 ) (78,193 ) Current maturities of long-term debt (507,650 ) (432,650 ) Short-term borrowings (a) (120,000 ) (614,673 ) Long-term debt $ 8,325,708 $ 8,091,629 (a) - Individual issuances of commercial paper under our commercial paper program generally mature in 90 days or less. These issuances are supported by and reduce the borrowing capacity under our $2.5 Billion Credit Agreement.

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ACCUMULATED OTHER COMPREHENSIVE INCOME (Tables)	9 Months Ended
	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss)	The following table sets forth the balance in accumulated other comprehensive loss for the period indicated: Unrealized Gains (Losses) on Risk- Management Assets/Liabilities (a) Pension and Postretirement Benefit Plan Obligations (a) (b) Unrealized Gains (Losses) on Risk- Management Assets/Liabilities of Unconsolidated Affiliates (a) Accumulated Other Comprehensive Loss (a) ( Thousands of dollars ) January 1, 2018 $ (81,915 ) $ (105,411 ) $ (1,204 ) $ (188,530 ) Other comprehensive income (loss) before reclassifications 10,729 (563 ) 5,336 15,502 Amounts reclassified from accumulated other comprehensive loss 43,397 9,649 (55 ) 52,991 Net current-period other comprehensive income (loss) attributable to ONEOK 54,126 9,086 5,281 68,493 Impact of adoption of ASU 2018-02 (c) (17,935 ) (20,166 ) — (38,101 ) September 30, 2018 $ (45,724 ) $ (116,491 ) $ 4,077 $ (158,138 ) (a) - All amounts are presented net of tax. (b) - Includes amounts related to supplemental executive retirement plan. (c) - We elected to adopt this guidance in the first quarter 2018, which allows a reclassification from accumulated other comprehensive income/loss to retained earnings for the stranded tax effects resulting from the Tax Cuts and Jobs Act. After adopting and applying this guidance, our accumulated other comprehensive loss balance does not include stranded taxes resulting from the Tax Cuts and Jobs Act.
Reclassification out of Accumulated Other Comprehensive Income (Loss)	The following table sets forth the effect of reclassifications from accumulated other comprehensive loss in our Consolidated Statements of Income for the periods indicated: Details about Accumulated Other Components Three Months Ended Nine Months Ended Affected Line Item in the Statements of Income September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Risk-management assets/liabilities Commodity contracts $ (20,630 ) $ (15,913 ) $ (42,430 ) $ (38,028 ) Commodity sales revenues Interest-rate contracts (4,383 ) (4,820 ) (13,929 ) (15,321 ) Interest expense (25,013 ) (20,733 ) (56,359 ) (53,349 ) Income before income taxes 5,752 7,671 12,962 13,077 Income taxes (19,261 ) (13,062 ) (43,397 ) (40,272 ) Net income Noncontrolling interests — — — (18,146 ) Less: Net income attributable to noncontrolling interests $ (19,261 ) $ (13,062 ) $ (43,397 ) $ (22,126 ) Net income attributable to ONEOK Pension and postretirement benefit plan obligations (a) Amortization of net loss $ (4,592 ) $ (3,811 ) $ (13,776 ) $ (11,435 ) Other income (expense) Amortization of unrecognized prior service credit 415 415 1,245 1,245 Other income (expense) (4,177 ) (3,396 ) (12,531 ) (10,190 ) Income before income taxes 961 1,358 2,882 4,076 Income taxes $ (3,216 ) $ (2,038 ) $ (9,649 ) $ (6,114 ) Net income attributable to ONEOK Risk-management assets/liabilities of unconsolidated affiliates $ 52 $ (83 ) $ 71 $ (264 ) Equity in net earnings from investments (12 ) 31 (16 ) 59 Income taxes 40 (52 ) 55 (205 ) Net income Noncontrolling interests — — — (106 ) Less: Net income attributable to noncontrolling interests $ 40 $ (52 ) $ 55 $ (99 ) Net income attributable to ONEOK Total reclassifications for the period attributable to ONEOK $ (22,437 ) $ (15,152 ) $ (52,991 ) $ (28,339 ) Net income attributable to ONEOK (a) - These components of accumulated other comprehensive loss are included in the computation of net periodic benefit cost. See Note H for additional detail of our net periodic benefit cost.

EARNINGS PER SHARE EARNINGS P_2

EARNINGS PER SHARE EARNINGS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	The following tables set forth the computation of basic and diluted EPS for the periods indicated: Three Months Ended September 30, 2018 Income Shares Per Share Amount ( Thousands, except per share amounts ) Basic EPS Net income attributable to ONEOK available for common stock $ 312,984 412,117 $ 0.76 Diluted EPS Effect of dilutive securities — 2,730 Net income attributable to ONEOK available for common stock and common stock equivalents $ 312,984 414,847 $ 0.75 Three Months Ended September 30, 2017 Income Shares Per Share Amount ( Thousands, except per share amounts ) Basic EPS Net income attributable to ONEOK available for common stock $ 165,466 380,907 $ 0.43 Diluted EPS Effect of dilutive securities — 2,512 Net income attributable to ONEOK available for common stock and common stock equivalents $ 165,466 383,419 $ 0.43 Nine Months Ended September 30, 2018 Income Shares Per Share Amount ( Thousands, except per share amounts ) Basic EPS Net income attributable to ONEOK available for common stock $ 857,990 411,400 $ 2.09 Diluted EPS Effect of dilutive securities — 2,635 Net income attributable to ONEOK available for common stock and common stock equivalents $ 857,990 414,035 $ 2.07 Nine Months Ended September 30, 2017 Income Shares Per Share Amount ( Thousands, except per share amounts ) Basic EPS Net income attributable to ONEOK available for common stock $ 324,303 268,108 $ 1.21 Diluted EPS Effect of dilutive securities — 2,241 Net income attributable to ONEOK available for common stock and common stock equivalents $ 324,303 270,349 $ 1.20

EMPLOYEE BENEFIT PLANS EMPLOY_2

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Tables)	9 Months Ended
	Sep. 30, 2018
Defined Benefit Plan [Abstract]
Components of net periodic benefit cost for pension and postretirement benefit plans	The following tables set forth the components of net periodic benefit cost for our pension and postretirement benefit plans for the periods indicated: Pension Benefits Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Components of net periodic benefit cost Service cost $ 1,832 $ 1,721 $ 5,496 $ 5,165 Interest cost 4,408 4,655 13,224 13,965 Expected return on plan assets (5,969 ) (5,336 ) (17,907 ) (16,008 ) Amortization of net loss 4,258 3,392 12,774 10,176 Net periodic benefit cost $ 4,529 $ 4,432 $ 13,587 $ 13,298 Postretirement Benefits Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Components of net periodic benefit cost Service cost $ 211 $ 165 $ 633 $ 495 Interest cost 527 565 1,581 1,695 Expected return on plan assets (672 ) (564 ) (2,016 ) (1,692 ) Amortization of prior service credit (415 ) (415 ) (1,245 ) (1,245 ) Amortization of net loss 334 419 1,002 1,259 Net periodic benefit cost (income) $ (15 ) $ 170 $ (45 ) $ 512

UNCONSOLIDATED AFFILIATES (Tabl

UNCONSOLIDATED AFFILIATES (Tables)	9 Months Ended
	Sep. 30, 2018
Equity In Net Earnings From Investments
Schedule of Equity Method Investments [Line Items]
Schedule of Equity Method Investments [Table Text Block]	The following table sets forth our equity in net earnings from investments for the periods indicated: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Northern Border Pipeline $ 16,486 $ 16,440 $ 48,863 $ 50,879 Overland Pass Pipeline Company 16,081 15,793 48,714 44,243 Roadrunner Gas Transmission 6,303 4,898 16,803 14,192 Other 443 2,927 1,690 9,671 Equity in net earnings from investments $ 39,313 $ 40,058 $ 116,070 $ 118,985 Impairment of equity investments $ — $ (4,270 ) $ — $ (4,270 )
Unconsolidated Affiliates Financial Information
Schedule of Equity Method Investments [Line Items]
Schedule of Equity Method Investments [Table Text Block]	The following table sets forth summarized combined financial information of our unconsolidated affiliates for the periods indicated: Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Income Statement Operating revenues $ 160,962 $ 163,627 $ 471,641 $ 475,510 Operating expenses $ 69,004 $ 69,740 $ 205,525 $ 206,141 Net income $ 85,361 $ 87,330 $ 247,754 $ 260,533 Distributions paid to us $ 47,197 $ 49,414 $ 145,437 $ 146,094

REVENUE REVENUE (Tables)

REVENUE REVENUE (Tables)	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue, Initial Application Period Cumulative Effect Transition [Table Text Block]	The impact on our Consolidated Income Statement and Balance Sheet is as follows (in thousands): Three Months Ended September 30, 2018 Income Statement As Reported Balance Without Adoption of Topic 606 Effect of Change Increase/(Decrease) Commodity sales $ 3,083,625 $ 3,129,947 $ (46,322 ) Services revenue $ 310,265 $ 707,633 $ (397,368 ) Cost of sales and fuel (exclusive of depreciation and operating costs) $ 2,560,765 $ 3,005,767 $ (445,002 ) Depreciation and amortization $ 107,383 $ 107,238 $ 145 Income taxes $ 102,983 $ 102,714 $ 269 Net income $ 313,916 $ 313,018 $ 898 Net income attributable to noncontrolling interests $ 657 $ 655 $ 2 Net income attributable to ONEOK $ 313,259 $ 312,363 $ 896 Nine Months Ended September 30, 2018 Income Statement As Reported Balance Without Adoption of Topic 606 Effect of Change Increase/(Decrease) Commodity sales $ 8,578,891 $ 8,625,213 $ (46,322 ) Services revenue $ 877,605 $ 1,986,563 $ (1,108,958 ) Cost of sales and fuel (exclusive of depreciation and operating costs) $ 7,104,609 $ 8,255,457 $ (1,150,848 ) Depreciation and amortization $ 317,908 $ 317,472 $ 436 Income taxes $ 266,285 $ 267,404 $ (1,119 ) Net income $ 862,144 $ 865,893 $ (3,749 ) Net income attributable to noncontrolling interests $ 3,329 $ 3,322 $ 7 Net income attributable to ONEOK $ 858,815 $ 862,571 $ (3,756 ) September 30, 2018 Balance Sheet As Reported Balance Without Adoption of Topic 606 Effect of Change Increase/(Decrease) Accounts receivable, net $ 1,085,075 $ 1,214,627 $ (129,552 ) Natural gas and natural gas liquids in storage $ 426,293 $ 439,035 $ (12,742 ) Other current assets $ 61,340 $ 60,198 $ 1,142 Property, plant and equipment $ 17,120,187 $ 17,098,053 $ 22,134 Accumulated depreciation and amortization $ 3,159,660 $ 3,157,852 $ 1,808 Other assets $ 191,170 $ 186,417 $ 4,753 Accounts payable $ 1,339,507 $ 1,469,059 $ (129,552 ) Other current liabilities $ 208,312 $ 206,658 $ 1,654 Deferred income taxes $ 132,242 $ 132,859 $ (617 ) Other deferred credits $ 350,400 $ 335,909 $ 14,491 Retained earnings/paid-in capital $ 7,662,673 $ 7,664,722 $ (2,049 )
Contract with Customer, Asset and Liability [Table Text Block]	The following tables set forth the changes in our contract asset and contract liability balances during the nine months ended September 30, 2018. Contract Assets ( Millions of dollars ) Balance at January 1, 2018 (a) $ 6.4 Amounts invoiced in excess of revenue recognized (0.7 ) Net additions 2.0 Balance at September 30, 2018 (b) $ 7.7 (a) - Balance includes $0.9 million of current assets. (b) - Contract assets of $2.9 million and $4.8 million are included in other current assets and other assets, respectively, in our Consolidated Balance Sheet. Contract Liabilities ( Millions of dollars ) Balance at January 1, 2018 (a) $ 33.3 Revenue recognized included in beginning balance (19.0 ) Net additions 24.0 Balance at September 30, 2018 (b) $ 38.3 (a) - Balance includes $19.5 million of current liabilities. (b) - Contract liabilities of $23.8 million and $14.5 million are included in other current liabilities and other deferred credits, respectively, in our Consolidated Balance Sheet.
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]	The following table presents aggregate value allocated to unsatisfied performance obligations as of September 30, 2018, and the amounts we expect to recognize in revenue in future periods, related primarily to firm transportation and storage contracts with remaining contract terms ranging from one month to 26 years: Expected Period of Recognition in Revenue ( Millions of dollars ) Remainder of 2018 $ 90.5 2019 296.2 2020 245.1 2021 237.4 2022 and beyond 1,090.9 Total estimated transaction price allocated to unsatisfied performance obligations $ 1,960.1

SEGMENTS (Tables)

SEGMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Segments	The following tables set forth certain selected financial information for our operating segments for the periods indicated: Three Months Ended Natural Gas Natural Gas Natural Gas Total ( Thousands of dollars ) NGL and condensate sales $ 501,163 $ 2,861,896 $ — $ 3,363,059 Residue natural gas sales 245,474 — 763 246,237 Gathering, processing and exchange services revenue 41,101 116,833 — 157,934 Transportation and storage revenue — 45,251 98,031 143,282 Other 3,517 2,308 6,400 12,225 Total revenues (c) 791,255 3,026,288 105,194 3,922,737 Cost of sales and fuel (exclusive of depreciation and operating costs) (542,463 ) (2,544,854 ) (2,384 ) (3,089,701 ) Operating costs (90,970 ) (101,126 ) (36,543 ) (228,639 ) Equity in net earnings from investments 74 16,450 22,789 39,313 Noncash compensation expense and other 1,703 2,268 1,050 5,021 Segment adjusted EBITDA $ 159,599 $ 399,026 $ 90,106 $ 648,731 Depreciation and amortization $ (49,223 ) $ (43,688 ) $ (13,625 ) $ (106,536 ) Capital expenditures $ 213,034 $ 444,780 $ 31,522 $ 689,336 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $316.0 million , of which $276.4 million related to sales within the segment, and cost of sales and fuel of $132.7 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $65.9 million and cost of sales and fuel of $5.5 million . (c) - Intersegment revenues for the Natural Gas Gathering and Processing, Natural Gas Liquids and Natural Gas Pipelines segments totaled $519.7 million , $7.4 million and $2.4 million , respectively. Three Months Ended September 30, 2018 Total Segments Other and Eliminations Total ( Thousands of dollars ) Reconciliations of total segments to consolidated NGL and condensate sales $ 3,363,059 $ (526,398 ) $ 2,836,661 Residue natural gas sales 246,237 — 246,237 Gathering, processing and exchange services revenue 157,934 — 157,934 Transportation and storage revenue 143,282 (2,370 ) 140,912 Other 12,225 (79 ) 12,146 Total revenues (a) $ 3,922,737 $ (528,847 ) $ 3,393,890 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (3,089,701 ) $ 528,936 $ (2,560,765 ) Operating costs $ (228,639 ) $ (1,732 ) $ (230,371 ) Depreciation and amortization $ (106,536 ) $ (847 ) $ (107,383 ) Equity in net earnings from investments $ 39,313 $ — $ 39,313 Capital expenditures $ 689,336 $ 4,967 $ 694,303 (a) - Noncustomer revenue for the three months ended September 30, 2018, totaled $(17.7) million related primarily to losses reclassified from accumulated other comprehensive income from derivatives on commodity contracts. Three Months Ended Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Total ( Thousands of dollars ) Sales to unaffiliated customers $ 453,432 $ 2,348,052 $ 104,340 $ 2,905,824 Intersegment revenues 329,496 153,927 2,098 485,521 Total revenues 782,928 2,501,979 106,438 3,391,345 Cost of sales and fuel (exclusive of depreciation and operating costs) (566,988 ) (2,136,207 ) (10,614 ) (2,713,809 ) Operating costs (79,559 ) (89,803 ) (29,568 ) (198,930 ) Equity in net earnings from investments 3,433 15,287 21,338 40,058 Other 2,136 2,663 (67 ) 4,732 Segment adjusted EBITDA $ 141,950 $ 293,919 $ 87,527 $ 523,396 Depreciation and amortization $ (46,842 ) $ (41,929 ) $ (12,765 ) $ (101,536 ) Impairment of long-lived assets and equity investments $ (20,240 ) $ — $ — $ (20,240 ) Capital expenditures $ 85,542 $ 27,024 $ 18,811 $ 131,377 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $293.1 million , of which $250.2 million related to sales within the segment, and cost of sales and fuel of $124.2 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $65.6 million and cost of sales and fuel of $10.5 million . Three Months Ended September 30, 2017 Total Segments Other and Eliminations Total ( Thousands of dollars ) Reconciliations of total segments to consolidated Sales to unaffiliated customers $ 2,905,824 $ 542 $ 2,906,366 Intersegment revenues 485,521 (485,521 ) — Total revenues $ 3,391,345 $ (484,979 ) $ 2,906,366 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (2,713,809 ) $ 484,393 $ (2,229,416 ) Operating costs $ (198,930 ) $ (5,404 ) $ (204,334 ) Depreciation and amortization $ (101,536 ) $ (762 ) $ (102,298 ) Impairment of long-lived assets and equity investments $ (20,240 ) $ — $ (20,240 ) Equity in net earnings from investments $ 40,058 $ — $ 40,058 Capital expenditures $ 131,377 $ 3,822 $ 135,199 Nine Months Ended Natural Gas Natural Gas Natural Gas Total ( Thousands of dollars ) NGL and condensate sales $ 1,362,159 $ 7,884,183 $ — $ 9,246,342 Residue natural gas sales 709,089 — 5,861 714,950 Gathering, processing and exchange services revenue 122,331 296,561 — 418,892 Transportation and storage revenue — 143,741 289,646 433,387 Other 6,596 8,202 19,390 34,188 Total revenues (c) 2,200,175 8,332,687 314,897 10,847,759 Cost of sales and fuel (exclusive of depreciation and operating costs) (1,478,044 ) (7,009,438 ) (10,475 ) (8,497,957 ) Operating costs (272,931 ) (289,328 ) (104,692 ) (666,951 ) Equity in net earnings from investments 948 49,456 65,666 116,070 Noncash compensation expense and other 6,868 9,789 3,701 20,358 Segment adjusted EBITDA $ 457,016 $ 1,093,166 $ 269,097 $ 1,819,279 Depreciation and amortization $ (145,120 ) $ (128,993 ) $ (41,320 ) $ (315,433 ) Total assets $ 5,811,140 $ 9,632,212 $ 2,109,897 $ 17,553,249 Capital expenditures $ 433,605 $ 786,635 $ 71,897 $ 1,292,137 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $910.3 million , of which $784.8 million related to sales within the segment, and cost of sales and fuel of $379.5 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $198.4 million and cost of sales and fuel of $20.4 million . (c) - Intersegment revenues for the Natural Gas Gathering and Processing, Natural Gas Liquids and Natural Gas Pipelines segments totaled $1,366.0 million , $20.1 million and $7.0 million , respectively. Nine Months Ended September 30, 2018 Total Segments Other and Eliminations Total ( Thousands of dollars ) Reconciliations of total segments to consolidated NGL and condensate sales $ 9,246,342 $ (1,383,864 ) $ 7,862,478 Residue natural gas sales 714,950 (778 ) 714,172 Gathering, processing and exchange services revenue 418,892 (21 ) 418,871 Transportation and storage revenue 433,387 (6,959 ) 426,428 Other 34,188 359 34,547 Total revenues (a) $ 10,847,759 $ (1,391,263 ) $ 9,456,496 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (8,497,957 ) $ 1,393,348 $ (7,104,609 ) Operating costs $ (666,951 ) $ (3,777 ) $ (670,728 ) Depreciation and amortization $ (315,433 ) $ (2,475 ) $ (317,908 ) Equity in net earnings from investments $ 116,070 $ — $ 116,070 Total assets $ 17,553,249 $ 358,065 $ 17,911,314 Capital expenditures $ 1,292,137 $ 17,518 $ 1,309,655 (a) - Noncustomer revenue for the nine months ended September 30, 2018, totaled $(32.1) million related primarily to losses reclassified from accumulated other comprehensive income from derivatives on commodity contracts. Nine Months Ended Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Total ( Thousands of dollars ) Sales to unaffiliated customers $ 1,286,669 $ 6,788,451 $ 305,019 $ 8,380,139 Intersegment revenues 843,350 455,197 6,086 1,304,633 Total revenues 2,130,019 7,243,648 311,105 9,684,772 Cost of sales and fuel (exclusive of depreciation and operating costs) (1,544,263 ) (6,188,501 ) (33,990 ) (7,766,754 ) Operating costs (223,546 ) (255,220 ) (91,813 ) (570,579 ) Equity in net earnings from investments 9,843 44,071 65,071 118,985 Other 2,125 1,459 772 4,356 Segment adjusted EBITDA $ 374,178 $ 845,457 $ 251,145 $ 1,470,780 Depreciation and amortization $ (137,843 ) $ (124,471 ) $ (37,906 ) $ (300,220 ) Impairment of long-lived assets and equity investments $ (20,240 ) $ — $ — $ (20,240 ) Total assets $ 5,385,778 $ 8,515,535 $ 2,040,445 $ 15,941,758 Capital expenditures $ 185,713 $ 59,813 $ 70,671 $ 316,197 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $878.8 million , of which $752.5 million related to sales within the segment, and cost of sales and fuel of $359.6 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $197.3 million and cost of sales and fuel of $32.9 million . Nine Months Ended September 30, 2017 Total Segments Other and Eliminations Total ( Thousands of dollars ) Reconciliations of total segments to consolidated Sales to unaffiliated customers $ 8,380,139 $ 1,610 $ 8,381,749 Intersegment revenues 1,304,633 (1,304,633 ) — Total revenues $ 9,684,772 $ (1,303,023 ) $ 8,381,749 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (7,766,754 ) $ 1,302,473 $ (6,464,281 ) Operating costs $ (570,579 ) $ (38,048 ) $ (608,627 ) Depreciation and amortization $ (300,220 ) $ (2,346 ) $ (302,566 ) Impairment of long-lived assets and equity investments $ (20,240 ) $ — $ (20,240 ) Equity in net earnings from investments $ 118,985 $ — $ 118,985 Total assets $ 15,941,758 $ 823,083 $ 16,764,841 Capital expenditures $ 316,197 $ 14,234 $ 330,431 Three Months Ended Nine Months Ended September 30, September 30, 2018 2017 2018 2017 ( Thousands of dollars ) Reconciliation of net income to total segment adjusted EBITDA Net income $ 313,916 $ 166,531 $ 862,144 $ 528,707 Add: Interest expense, net of capitalized interest 121,910 126,533 351,131 361,468 Depreciation and amortization 107,383 102,298 317,908 302,566 Income taxes 102,983 97,128 266,285 195,913 Impairment charges — 20,240 — 20,240 Noncash compensation expense 5,829 4,883 27,195 9,790 Other corporate costs and noncash items (a) (3,290 ) 5,783 (5,384 ) 52,096 Total segment adjusted EBITDA $ 648,731 $ 523,396 $ 1,819,279 $ 1,470,780 (a) - The nine months ended September 30, 2017, includes our April 2017 $20 million contribution of Series E Preferred Stock to the Foundation and costs related to the Merger Transaction of $29.5 million .

SUPPLEMENTAL CONDENSED CONSOL_2

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2018
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Statements of Income	Condensed Consolidating Statements of Income Three Months Ended September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ — $ 3,083.6 $ — $ 3,083.6 Services — — — 310.8 (0.5 ) 310.3 Total revenues — — — 3,394.4 (0.5 ) 3,393.9 Cost of sales and fuel (exclusive of items shown separately below) — — — 2,560.8 — 2,560.8 Operating expenses 2.0 — — 336.3 (0.5 ) 337.8 Gain on sale of assets — — — (0.2 ) — (0.2 ) Operating income (2.0 ) — — 497.5 — 495.5 Equity in net earnings from investments 457.3 457.1 457.1 30.1 (1,362.3 ) 39.3 Other income (expense), net 9.3 80.3 80.3 (5.3 ) (160.6 ) 4.0 Interest expense, net (49.1 ) (80.3 ) (80.3 ) (72.8 ) 160.6 (121.9 ) Income before income taxes 415.5 457.1 457.1 449.5 (1,362.3 ) 416.9 Income taxes (102.3 ) — — (0.7 ) — (103.0 ) Net income 313.2 457.1 457.1 448.8 (1,362.3 ) 313.9 Less: Net income attributable to noncontrolling interests — — — 0.7 — 0.7 Net income attributable to ONEOK 313.2 457.1 457.1 448.1 (1,362.3 ) 313.2 Less: Preferred stock dividends 0.2 — — — — 0.2 Net income available to common shareholders $ 313.0 $ 457.1 $ 457.1 $ 448.1 $ (1,362.3 ) $ 313.0 Three Months Ended September 30, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ — $ 2,322.5 $ — $ 2,322.5 Services — — — 584.3 (0.5 ) 583.8 Total revenues — — — 2,906.8 (0.5 ) 2,906.3 Cost of sales and fuel (exclusive of items shown separately below) — — — 2,229.4 — 2,229.4 Operating expenses 1.2 — 2.6 303.3 (0.5 ) 306.6 Impairment of long-lived assets — — — 16.0 — 16.0 Gain on sale of assets — — — (0.3 ) — (0.3 ) Operating income (1.2 ) — (2.6 ) 358.4 — 354.6 Equity in net earnings from investments 298.0 298.3 300.9 27.6 (884.7 ) 40.1 Impairment of equity investments — — — (4.3 ) — (4.3 ) Other income (expense), net 4.1 86.1 86.1 (4.3 ) (172.2 ) (0.2 ) Interest expense, net (43.2 ) (86.1 ) (86.1 ) (83.3 ) 172.2 (126.5 ) Income before income taxes 257.7 298.3 298.3 294.1 (884.7 ) 263.7 Income taxes (91.9 ) — — (5.3 ) — (97.2 ) Net income 165.8 298.3 298.3 288.8 (884.7 ) 166.5 Less: Net income attributable to noncontrolling interests 0.1 — — 0.7 — 0.8 Net income attributable to ONEOK 165.7 298.3 298.3 288.1 (884.7 ) 165.7 Less: Preferred stock dividends 0.2 — — — — 0.2 Net income available to common shareholders $ 165.5 $ 298.3 $ 298.3 $ 288.1 $ (884.7 ) $ 165.5 Nine Months Ended September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ — $ 8,578.9 $ — $ 8,578.9 Services — — — 879.1 (1.5 ) 877.6 Total revenues — — — 9,458.0 (1.5 ) 9,456.5 Cost of sales and fuel (exclusive of items shown separately below) — — — 7,104.6 — 7,104.6 Operating expenses 3.3 — — 986.8 (1.5 ) 988.6 Gain on sale of assets — — — (0.3 ) — (0.3 ) Operating income (3.3 ) — — 1,366.9 — 1,363.6 Equity in net earnings from investments 1,226.6 1,231.2 1,231.2 86.2 (3,659.1 ) 116.1 Other income (expense), net 23.1 234.9 234.9 (23.3 ) (469.8 ) (0.2 ) Interest expense, net (129.2 ) (234.9 ) (234.9 ) (221.9 ) 469.8 (351.1 ) Income before income taxes 1,117.2 1,231.2 1,231.2 1,207.9 (3,659.1 ) 1,128.4 Income taxes (258.4 ) — — (7.9 ) — (266.3 ) Net income 858.8 1,231.2 1,231.2 1,200.0 (3,659.1 ) 862.1 Less: Net income attributable to noncontrolling interests — — — 3.3 — 3.3 Net income attributable to ONEOK 858.8 1,231.2 1,231.2 1,196.7 (3,659.1 ) 858.8 Less: Preferred stock dividends 0.8 — — — — 0.8 Net income available to common shareholders $ 858.0 $ 1,231.2 $ 1,231.2 $ 1,196.7 $ (3,659.1 ) $ 858.0 Nine Months Ended September 30, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ — $ 6,700.3 $ — $ 6,700.3 Services — — — 1,683.0 (1.5 ) 1,681.5 Total revenues — — — 8,383.3 (1.5 ) 8,381.8 Cost of sales and fuel (exclusive of items shown separately below) — — — 6,464.3 — 6,464.3 Operating expenses 25.9 — 8.8 878.0 (1.5 ) 911.2 Impairment of long-lived assets — — — 16.0 — 16.0 Gain on sale of assets — — — (0.9 ) — (0.9 ) Operating income (25.9 ) — (8.8 ) 1,025.9 — 991.2 Equity in net earnings from investments 842.0 845.9 854.7 72.1 (2,495.7 ) 119.0 Impairment of equity investments — — — (4.3 ) — (4.3 ) Other income (expense), net (15.5 ) 272.2 272.2 (4.3 ) (544.4 ) (19.8 ) Interest expense, net (93.5 ) (272.2 ) (272.2 ) (268.0 ) 544.4 (361.5 ) Income before income taxes 707.1 845.9 845.9 821.4 (2,495.7 ) 724.6 Income taxes (180.9 ) — — (15.0 ) — (195.9 ) Net income 526.2 845.9 845.9 806.4 (2,495.7 ) 528.7 Less: Net income attributable to noncontrolling interests 201.4 — — 2.5 — 203.9 Net income attributable to ONEOK 324.8 845.9 845.9 803.9 (2,495.7 ) 324.8 Less: Preferred stock dividends 0.5 — — — — 0.5 Net income available to common shareholders $ 324.3 $ 845.9 $ 845.9 $ 803.9 $ (2,495.7 ) $ 324.3
Condensed Consolidating Statements of Comprehensive Income	Condensed Consolidating Statements of Comprehensive Income Three Months Ended September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 313.2 $ 457.1 $ 457.1 $ 448.8 $ (1,362.3 ) $ 313.9 Other comprehensive income (loss), net of tax Unrealized gains (losses) on derivatives, net of tax 20.2 (30.7 ) (30.7 ) (23.7 ) 61.4 (3.5 ) Realized (gains) losses on derivatives in net income, net of tax — 25.0 20.6 14.9 (41.2 ) 19.3 Change in pension and postretirement benefit plan liability, net of tax 3.2 — — — — 3.2 Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax — 2.0 2.0 1.5 (4.0 ) 1.5 Total other comprehensive income (loss), net of tax 23.4 (3.7 ) (8.1 ) (7.3 ) 16.2 20.5 Comprehensive income 336.6 453.4 449.0 441.5 (1,346.1 ) 334.4 Less: Comprehensive income attributable to noncontrolling interests — — — 0.7 — 0.7 Comprehensive income attributable to ONEOK $ 336.6 $ 453.4 $ 449.0 $ 440.8 $ (1,346.1 ) $ 333.7 Three Months Ended September 30, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 165.8 $ 298.3 $ 298.3 $ 288.8 $ (884.7 ) $ 166.5 Other comprehensive income (loss), net of tax Unrealized gains (losses) on derivatives, net of tax 18.4 (61.9 ) (42.4 ) (19.5 ) 84.8 (20.6 ) Realized (gains) losses on derivatives in net income, net of tax 0.6 19.8 15.9 8.6 (31.8 ) 13.1 Change in pension and postretirement benefit plan liability, net of tax 2.0 — — — — 2.0 Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax — (0.3 ) (0.3 ) (0.2 ) 0.6 (0.2 ) Total other comprehensive income (loss), net of tax 21.0 (42.4 ) (26.8 ) (11.1 ) 53.6 (5.7 ) Comprehensive income 186.8 255.9 271.5 277.7 (831.1 ) 160.8 Less: Comprehensive income attributable to noncontrolling interests — — — 0.7 — 0.7 Comprehensive income attributable to ONEOK $ 186.8 $ 255.9 $ 271.5 $ 277.0 $ (831.1 ) $ 160.1 Nine Months Ended September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 858.8 $ 1,231.2 $ 1,231.2 $ 1,200.0 $ (3,659.1 ) $ 862.1 Other comprehensive income (loss), net of tax Unrealized gains (losses) on derivatives, net of tax 54.0 (56.2 ) (56.2 ) (43.3 ) 112.4 10.7 Realized (gains) losses on derivatives in net income, net of tax 1.9 53.9 42.4 30.0 (84.8 ) 43.4 Change in pension and postretirement benefit plan liability, net of tax 9.7 (0.6 ) — — — 9.1 Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax — 6.9 6.9 5.3 (13.8 ) 5.3 Total other comprehensive income (loss), net of tax 65.6 4.0 (6.9 ) (8.0 ) 13.8 68.5 Comprehensive income 924.4 1,235.2 1,224.3 1,192.0 (3,645.3 ) 930.6 Less: Comprehensive income attributable to noncontrolling interests — — — 3.3 — 3.3 Comprehensive income attributable to ONEOK $ 924.4 $ 1,235.2 $ 1,224.3 $ 1,188.7 $ (3,645.3 ) $ 927.3 Nine Months Ended September 30, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 526.2 $ 845.9 $ 845.9 $ 806.4 $ (2,495.7 ) $ 528.7 Other comprehensive income (loss), net of tax Unrealized gains (losses) on derivatives, net of tax 18.1 (38.8 ) (6.1 ) 13.3 12.2 (1.3 ) Realized (gains) losses on derivatives in net income, net of tax 1.6 50.7 38.0 26.0 (76.0 ) 40.3 Change in pension and postretirement benefit plan liability, net of tax 6.1 — — — — 6.1 Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax — (1.5 ) (1.5 ) (1.2 ) 3.0 (1.2 ) Total other comprehensive income (loss), net of tax 25.8 10.4 30.4 38.1 (60.8 ) 43.9 Comprehensive income 552.0 856.3 876.3 844.5 (2,556.5 ) 572.6 Less: Comprehensive income attributable to noncontrolling interests 232.4 — — 2.5 — 234.9 Comprehensive income attributable to ONEOK $ 319.6 $ 856.3 $ 876.3 $ 842.0 $ (2,556.5 ) $ 337.7
Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheets September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total Assets ( Millions of dollars ) Current assets Cash and cash equivalents $ 84.5 $ — $ — $ — $ — $ 84.5 Accounts receivable, net — — — 1,085.1 — 1,085.1 Materials and supplies — — — 128.6 — 128.6 Natural gas and natural gas liquids in storage — — — 426.3 — 426.3 Other current assets 10.4 — — 73.0 — 83.4 Total current assets 94.9 — — 1,713.0 — 1,807.9 Property, plant and equipment Property, plant and equipment 141.0 — — 16,979.2 — 17,120.2 Accumulated depreciation and amortization 90.5 — — 3,069.2 — 3,159.7 Net property, plant and equipment 50.5 — — 13,910.0 — 13,960.5 Investments and other assets Investments 5,977.5 3,359.0 9,223.2 796.8 (18,374.9 ) 981.6 Intercompany notes receivable 4,769.1 7,682.5 1,818.3 — (14,269.9 ) — Other assets 174.3 — — 988.2 (1.2 ) 1,161.3 Total investments and other assets 10,920.9 11,041.5 11,041.5 1,785.0 (32,646.0 ) 2,142.9 Total assets $ 11,066.3 $ 11,041.5 $ 11,041.5 $ 17,408.0 $ (32,646.0 ) $ 17,911.3 Liabilities and equity Current liabilities Current maturities of long-term debt $ — $ 500.0 $ — $ 7.7 $ — $ 507.7 Short-term borrowings 120.0 — — — — 120.0 Accounts payable 5.1 — — 1,334.4 — 1,339.5 Other current liabilities 71.8 67.6 — 343.6 — 483.0 Total current liabilities 196.9 567.6 — 1,685.7 — 2,450.2 Intercompany debt — — 7,682.5 6,587.4 (14,269.9 ) — Long-term debt, excluding current maturities 3,962.2 4,340.4 — 23.1 — 8,325.7 Deferred credits and other liabilities Deferred income taxes 25.8 — — 107.6 (1.2 ) 132.2 Other deferred credits 228.6 — — 121.8 — 350.4 Total deferred credits and other liabilities 254.4 — — 229.4 (1.2 ) 482.6 Commitments and contingencies Equity 6,652.8 6,133.5 3,359.0 8,882.4 (18,374.9 ) 6,652.8 Total liabilities and equity $ 11,066.3 $ 11,041.5 $ 11,041.5 $ 17,408.0 $ (32,646.0 ) $ 17,911.3 December 31, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total Assets ( Millions of dollars ) Current assets Cash and cash equivalents $ 37.2 $ — $ — $ — $ — $ 37.2 Accounts receivable, net — — — 1,203.0 — 1,203.0 Materials and supplies — — — 90.3 — 90.3 Natural gas and natural gas liquids in storage — — — 342.3 — 342.3 Other current assets 9.8 1.3 — 80.6 — 91.7 Total current assets 47.0 1.3 — 1,716.2 — 1,764.5 Property, plant and equipment Property, plant and equipment 128.3 — — 15,431.3 — 15,559.6 Accumulated depreciation and amortization 86.4 — — 2,775.1 — 2,861.5 Net property, plant and equipment 41.9 — — 12,656.2 — 12,698.1 Investments and other assets Investments 5,752.1 3,133.7 8,058.4 803.0 (16,744.0 ) 1,003.2 Intercompany notes receivable 2,926.9 8,627.8 3,703.1 — (15,257.8 ) — Other assets 416.9 0.2 — 1,007.4 (44.4 ) 1,380.1 Total investments and other assets 9,095.9 11,761.7 11,761.5 1,810.4 (32,046.2 ) 2,383.3 Total assets $ 9,184.8 $ 11,763.0 $ 11,761.5 $ 16,182.8 $ (32,046.2 ) $ 16,845.9 Liabilities and equity Current liabilities Current maturities of long-term debt $ — $ 425.0 $ — $ 7.7 $ — $ 432.7 Short-term borrowings 614.7 — — — — 614.7 Accounts payable 12.0 — — 1,128.6 — 1,140.6 Other current liabilities 65.9 85.0 — 328.4 — 479.3 Total current liabilities 692.6 510.0 — 1,464.7 — 2,667.3 Intercompany debt — — 8,627.8 6,630.0 (15,257.8 ) — Long-term debt, excluding current maturities 2,726.4 5,336.4 — 28.8 — 8,091.6 Deferred credits and other liabilities Deferred income taxes — — — 97.1 (44.4 ) 52.7 Other deferred credits 237.9 — — 111.0 — 348.9 Total deferred credits and other liabilities 237.9 — — 208.1 (44.4 ) 401.6 Commitments and contingencies Equity Equity excluding noncontrolling interests in consolidated subsidiaries 5,527.9 5,916.6 3,133.7 7,693.7 (16,744.0 ) 5,527.9 Noncontrolling interests in consolidated subsidiaries — — — 157.5 — 157.5 Total equity 5,527.9 5,916.6 3,133.7 7,851.2 (16,744.0 ) 5,685.4 Total liabilities and equity $ 9,184.8 $ 11,763.0 $ 11,761.5 $ 16,182.8 $ (32,046.2 ) $ 16,845.9
Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statements of Cash Flows Nine Months Ended September 30, 2018 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Operating activities Cash provided by operating activities $ 964.4 $ 993.8 $ 48.9 $ 1,507.4 $ (1,998.0 ) $ 1,516.5 Investing activities Capital expenditures (15.0 ) — — (1,294.7 ) — (1,309.7 ) Cash paid for acquisition (195.0 ) — — — — (195.0 ) Contributions to unconsolidated affiliates — — (0.5 ) (0.3 ) — (0.8 ) Other investing activities — — 10.8 9.9 — 20.7 Cash provided by (used in) investing activities (210.0 ) — 10.3 (1,285.1 ) — (1,484.8 ) Financing activities Dividends paid (983.1 ) (999.0 ) (999.0 ) — 1,998.0 (983.1 ) Distributions to noncontrolling interests — — — (3.5 ) — (3.5 ) Intercompany borrowings (advances), net (1,640.5 ) 930.2 939.8 (229.5 ) — — Borrowing (repayment) of short-term borrowings, net (494.7 ) — — — — (494.7 ) Issuance of long-term debt, net of discounts 1,245.8 — — — — 1,245.8 Repayment of long-term debt — (925.0 ) — (5.7 ) — (930.7 ) Issuance of common stock 1,195.1 — — — — 1,195.1 Other, net (29.7 ) — — 16.4 — (13.3 ) Cash provided by (used in) financing activities (707.1 ) (993.8 ) (59.2 ) — (222.3 ) 1,998.0 15.6 Change in cash and cash equivalents 47.3 — — — — 47.3 Cash and cash equivalents at beginning of period 37.2 — — — — 37.2 Cash and cash equivalents at end of period $ 84.5 $ — $ — $ — $ — $ 84.5 Nine Months Ended September 30, 2017 ( Unaudited ) Parent Issuer & Guarantor Subsidiary Issuer & Guarantor Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Operating activities Cash provided by operating activities $ 620.8 $ 994.3 $ 42.1 $ 1,005.8 $ (1,727.0 ) $ 936.0 Investing activities Capital expenditures (0.5 ) — — (329.9 ) — (330.4 ) Contributions to unconsolidated affiliates — — (83.0 ) (4.7 ) — (87.7 ) Other investing activities — — 11.2 12.3 — 23.5 Cash used in investing activities (0.5 ) — (71.8 ) (322.3 ) — (394.6 ) Financing activities Dividends paid (543.4 ) (999.0 ) (999.0 ) — 1,998.0 (543.4 ) Distributions to noncontrolling interests — — — (4.1 ) (271.0 ) (275.1 ) Intercompany borrowings (advances), net (2,376.9 ) 2,022.2 1,028.3 (673.6 ) — — Borrowing (repayment) of short-term borrowings, net 932.3 (1,110.3 ) — — — (178.0 ) Issuance of long-term debt, net of discounts 1,190.1 — — — — 1,190.1 Repayment of long-term debt (87.1 ) (900.0 ) — (5.8 ) — (992.9 ) Issuance of common stock 45.8 — — — — 45.8 Other, net (17.9 ) (7.2 ) — — — (25.1 ) Cash provided by (used in) financing activities (857.1 ) (994.3 ) 29.3 (683.5 ) 1,727.0 (778.6 ) Change in cash and cash equivalents (236.8 ) — (0.4 ) — — (237.2 ) Cash and cash equivalents at beginning of period 248.5 — 0.4 — — 248.9 Cash and cash equivalents at end of period $ 11.7 $ — $ — $ — $ — $ 11.7

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Entity Information [Line Items]
Common Stock, Shares, Issued	445,016,234			445,016,234		423,166,234
Business Acquisition, Description of Acquired Entity			On June 30, 2017, we completed the acquisition of all of the outstanding common units of ONEOK Partners that we did not already own at a fixed exchange ratio of 0.985 of a share of our common stock for each ONEOK Partners common unit. We issued 168.9 million shares of our common stock to third-party common unitholders of ONEOK Partners in exchange for all of the 171.5 million outstanding common units of ONEOK Partners that we previously did not own. As a result of the completion of the Merger Transaction, common units of ONEOK Partners are no longer publicly traded.
General partnership ownership interest			41.20%	100.00%		100.00%
Impairment of long-lived assets	$ 0	$ 15,970		$ 0	$ 15,970
Equity Method Investment, Other than Temporary Impairment	$ 0	$ 4,270		$ 0	$ 4,270

FAIR VALUE MEASUREMENTS - Part

FAIR VALUE MEASUREMENTS - Part 1 (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash held - offsetting derivative net asset positions under master-netting arrangements	$ 0	$ 0
Cash posted - total	67,800	49,700
Cash posted - offsetting derivative net liability positions under master-netting arrangements	46,200	29,500
Cash posted - remaining in excess of derivative net liability positions included in consolidated Balance Sheets	21,600	20,200
Long-term debt, Fair Value	9,300,000	9,300,000
Long-term debt	8,800,000	8,500,000
Fair Value, Measurements, Recurring [Member]
Derivative assets
Financial contracts	0	0
Interest-rate contracts	50,509	49,960
Total derivative assets	50,509	49,960
Derivative assets netting	(54,129)	(24,455)
Derivative liabilities
Financial contracts	0	(32)
Physical contracts	(2,010)	(4,781)
Total derivative liabilities	(2,010)	(4,813)
Derivative liabilities netting	100,350	53,936
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member]
Derivative assets
Financial contracts	54,129	24,455
Interest-rate contracts	50,509	49,960
Total derivative assets	104,638	74,415
Derivative liabilities
Financial contracts	(100,350)	(53,968)
Physical contracts	(2,010)	(4,781)
Total derivative liabilities	(102,360)	(58,749)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative assets
Financial contracts	183	4,252
Interest-rate contracts	0	0
Total derivative assets	183	4,252
Derivative liabilities
Financial contracts	(17,337)	(5,708)
Physical contracts	0	0
Total derivative liabilities	(17,337)	(5,708)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative assets
Financial contracts	0	0
Interest-rate contracts	50,509	49,960
Total derivative assets	50,509	49,960
Derivative liabilities
Financial contracts	0	0
Physical contracts	0	0
Total derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative assets
Financial contracts	53,946	20,203
Interest-rate contracts	0	0
Total derivative assets	53,946	20,203
Derivative liabilities
Financial contracts	(83,013)	(48,260)
Physical contracts	(2,010)	(4,781)
Total derivative liabilities	$ (85,023)	$ (53,041)

FAIR VALUE MEASUREMENTS - Par_2

FAIR VALUE MEASUREMENTS - Part 2 (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]
Net assets (liabilities) at beginning of period	$ (23,501)	$ 750	$ (32,838)	$ (23,319)
Total realized/unrealized gains (losses):
Included in earnings	(22)	(675)	(122)	(417)
Included in other comprehensive income (loss)	(7,554)	(26,581)	1,883	(2,770)
Net assets (liabilities) at end of period	(31,077)	(26,506)	(31,077)	(26,506)
Transfers between levels	$ 0	$ 0	$ 0	$ 0

RISK MANAGEMENT AND HEDGING A_3

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES Part 1 (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Derivative, Fair Value [Line Items]
Assets	$ 104,638,000	$ 74,415,000
(Liabilities)	(102,360,000)	(58,749,000)
Derivative, Net Liability Position, Aggregate Fair Value	0
Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	100,381,000	66,938,000
(Liabilities)	(98,122,000)	(51,438,000)
Derivatives not designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	4,257,000	7,477,000
(Liabilities)	(4,238,000)	(7,311,000)
Natural Gas Pipelines [Member]
Derivative, Fair Value [Line Items]
Derivative, Fair Value, Net	0	0
Other Current Assets [Member] | Commodity contracts | Financial contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	46,411,000	16,978,000
Other Current Assets [Member] | Commodity contracts | Financial contracts | Derivatives not designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	4,257,000	7,477,000
Other Current Assets [Member] | Commodity contracts | Physical contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	0	0
Other Current Assets [Member] | Interest-rate contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	0	1,330,000
Other Current Liabilities [Member] | Commodity contracts | Financial contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
(Liabilities)	(84,174,000)	(42,819,000)
Other Current Liabilities [Member] | Commodity contracts | Financial contracts | Derivatives not designated as hedging instruments
Derivative, Fair Value [Line Items]
(Liabilities)	(4,238,000)	(7,311,000)
Other Current Liabilities [Member] | Commodity contracts | Physical contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
(Liabilities)	(1,898,000)	(4,781,000)
Other Current Liabilities [Member] | Interest-rate contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
(Liabilities)	0	0
Other Assets [Member] | Commodity contracts | Financial contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	3,461,000	0
Other Assets [Member] | Commodity contracts | Physical contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	0	0
Other Assets [Member] | Interest-rate contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	50,509,000	48,630,000
Other Liabilities [Member] | Commodity contracts | Financial contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
(Liabilities)	(11,938,000)	(3,838,000)
Other Liabilities [Member] | Commodity contracts | Physical contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
(Liabilities)	(112,000)	0
Other Liabilities [Member] | Interest-rate contracts | Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
(Liabilities)	$ 0	$ 0

RISK MANAGEMENT AND HEDGING A_4

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES, Part 2 (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)MMcfMMBbls	Dec. 31, 2017USD ($)MMcfMMBbls
Designated as Hedging Instrument [Member] | Futures and swaps | - Natural gas (Bcf) | Fixed price | Purchased/ Payor
Derivative [Line Items]
Notional Amount | MMcf	0	0
Designated as Hedging Instrument [Member] | Futures and swaps | - Natural gas (Bcf) | Fixed price | Sold/ Receiver
Derivative [Line Items]
Notional Amount | MMcf	(36,100)	(24,500)
Designated as Hedging Instrument [Member] | Futures and swaps | - Natural gas (Bcf) | Basis | Purchased/ Payor
Derivative [Line Items]
Notional Amount | MMcf	0	0
Designated as Hedging Instrument [Member] | Futures and swaps | - Natural gas (Bcf) | Basis | Sold/ Receiver
Derivative [Line Items]
Notional Amount | MMcf	(36,100)	(24,500)
Designated as Hedging Instrument [Member] | Futures, forwards and swaps | - Crude oil and NGLs (MMBbl) | Fixed price | Purchased/ Payor
Derivative [Line Items]
Notional Amount | MMBbls	7.2	3.5
Designated as Hedging Instrument [Member] | Futures, forwards and swaps | - Crude oil and NGLs (MMBbl) | Fixed price | Sold/ Receiver
Derivative [Line Items]
Notional Amount | MMBbls	(16.5)	(11.1)
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Purchased/ Payor
Derivative [Line Items]
Derivative, Notional Amount	$ 1,750,000	$ 1,750,000
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Sold/ Receiver
Derivative [Line Items]
Derivative, Notional Amount	$ 0	$ 0
Not Designated as Hedging Instrument [Member] | Futures, forwards and swaps | - Crude oil and NGLs (MMBbl) | Fixed price | Purchased/ Payor
Derivative [Line Items]
Notional Amount | MMBbls	0.2	0.8
Not Designated as Hedging Instrument [Member] | Futures, forwards and swaps | - Crude oil and NGLs (MMBbl) | Fixed price | Sold/ Receiver
Derivative [Line Items]
Notional Amount | MMBbls	(0.2)	(0.8)
LIBOR Based Interest Payments [Member] | Cash Flow Hedging [Member] | Forward Contracts [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional Amount Of Cash Flow Hedge Instruments Settled	$ 500,000
Derivative, Notional Amount		$ 500,000
Forecasted Debt Issuances [Member] | Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount, New Contracts	1,500,000
Notional Amount Of Cash Flow Hedge Instruments Settled	1,000,000
Forecasted Debt Issuances [Member] | Cash Flow Hedging [Member] | Forward Contracts [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 1,800,000	$ 1,300,000

RISK MANAGEMENT AND HEDGING A_5

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES Part 3 (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (158,138)		$ (158,138)		$ (188,530)
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive (Loss), Net	(4,580)		13,933
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Net		$ (32,837)		$ (9,976)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Net	(25,013)		(56,359)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Net		(20,733)		(53,349)
Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) On Cash Flow Hedges Net Of Tax Accumulated Other Comprehensive Income Loss	(37,200)		(37,200)
Price Risk Cash Flow Hedge Unrealized Gain (Loss) to be Reclassified During Next 12 Months	(30,500)		(30,500)
Commodity Cash Flow Hedge Gain (Loss) To Be Reclassified After Next 12 Months Net	(6,700)		(6,700)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive (Loss), Net	(30,783)		(56,246)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Net		(42,450)		(6,123)
Commodity Contract [Member] | Commodity sales revenues | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Net	(20,630)		(42,430)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Net		(15,913)		(38,028)
Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of accumulated other comprehensive income (loss) attributable primarily to settled interest-rate swaps.	(43,900)		(43,900)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	(13,600)		(13,600)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive (Loss), Net	26,203		70,179
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Net		9,613		(3,853)
Interest Rate Contract [Member] | Interest expense | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Net	$ (4,383)		$ (13,929)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Net		$ (4,820)		$ (15,321)

DEBT DEBT (Details)

DEBT DEBT (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)Rate	Dec. 31, 2017USD ($)Rate
Debt Instrument [Line Items]
Total Debt	$ 9,023,267	$ 9,198,677
Unamortized Portion of Terminated Swaps	17,179	18,468
Unamortized debt issuance costs and discounts	(87,088)	(78,193)
Current maturities of long-term debt	(507,650)	(432,650)
Short-term borrowings	(120,000)	(614,673)
Long-term debt	8,325,708	8,091,629
$2.5 Billion Credit Agreement [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	2,500,000
Line of credit facility sublimit	100,000
Line of Credit Facility Swingline Subfacility	200,000
Line Of Credit Facility Option To Increase Borrowing Capacity	$ 3,500,000
Line of Credit Facility, Interest Rate Description	borrowings, if any, will accrue at LIBOR plus 110 basis points
Line Of Credit Facility, Annual Facility Fee Description	the annual facility fee is 15 basis points
Indebtedness To Adjusted Ebitda Current	3.5
Debt Instrument, Covenant Description	Among other things, these covenants include maintaining a ratio of indebtedness to adjusted EBITDA (EBITDA, as defined in our $2.5 Billion Credit Agreement, adjusted for all noncash charges and increased for projected EBITDA from certain lender-approved capital expansion projects) of no more than 5.5 to 1 at September 30, 2018. During the third quarter 2018, we acquired the remaining 20 percent interest in WTLPG for $195 million, which increased the covenant to 5.5 to 1 for the third quarter 2018 and the two following quarters. Thereafter, the covenant will decrease to 5.0 to 1. Our $2.5 Billion Credit Agreement includes a $100 million sublimit for the issuance of standby letters of credit and a $200 million sublimit for swingline loans. Under the terms of our $2.5 Billion Credit Agreement, we may request an increase in the size of the facility to an aggregate of $3.5 billion by either commitments from new lenders or increased commitments from existing lenders. Our $2.5 Billion Credit Agreement contains provisions for an applicable margin rate and an annual facility fee, both of which adjust with changes in our credit ratings. Based on our current credit ratings, borrowings, if any, will accrue at LIBOR plus 110 basis points, and the annual facility fee is 15 basis points. We have the option to request an additional one year extension, subject to lender approval, which may be used for working capital, capital expenditures, acquisitions and mergers, the issuance of letters of credit and for other general corporate purposes. At September 30, 2018, we had no borrowings outstanding, our ratio of indebtedness to adjusted EBITDA was 3.5 to 1, and we were in compliance with all covenants under our $2.5 Billion Credit Agreement.
Senior Notes [Member]
Debt Instrument [Line Items]
Senior Notes, Noncurrent	$ 1,250,000
Proceeds from Debt, Net of Issuance Costs	1,230,000
Guardian Pipeline [Member] | Notes Payables 1 due 2022 [Member]
Debt Instrument [Line Items]
Total Debt	$ 30,870	36,607
Weighed Average Interest Rate (in hundredths) | Rate	7.85%
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2018 [Member]
Debt Instrument [Line Items]
Total Debt	$ 0	425,000
Repayment of Senior Notes	$ 425,000
Interest Rate (in hundredths) | Rate	3.20%
Subsidiary Issuer [Member] | Term Loan Agreement [Member]
Debt Instrument [Line Items]
Total Debt	$ 0	$ 500,000
Repayment of Senior Notes	500,000
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate | Rate		2.87%
Subsidiary Issuer [Member] | Notes Payables due 2019 [Member]
Debt Instrument [Line Items]
Total Debt	$ 500,000	$ 500,000
Interest Rate (in hundredths) | Rate	8.625%
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2020 [Member]
Debt Instrument [Line Items]
Total Debt	$ 300,000	300,000
Interest Rate (in hundredths) | Rate	3.80%
Subsidiary Issuer [Member] | Note Payable 2 from Public Offering Due 2022 [Member]
Debt Instrument [Line Items]
Total Debt	$ 900,000	900,000
Interest Rate (in hundredths) | Rate	3.375%
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2023 [Member]
Debt Instrument [Line Items]
Total Debt	$ 425,000	425,000
Interest Rate (in hundredths) | Rate	5.00%
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2025 [Member]
Debt Instrument [Line Items]
Total Debt	$ 500,000	500,000
Interest Rate (in hundredths) | Rate	4.90%
Subsidiary Issuer [Member] | Notes Payables due 2036 [Member]
Debt Instrument [Line Items]
Total Debt	$ 600,000	600,000
Interest Rate (in hundredths) | Rate	6.65%
Subsidiary Issuer [Member] | Notes Payables due 2037 [Member]
Debt Instrument [Line Items]
Total Debt	$ 600,000	600,000
Interest Rate (in hundredths) | Rate	6.85%
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2041 [Member]
Debt Instrument [Line Items]
Total Debt	$ 650,000	650,000
Interest Rate (in hundredths) | Rate	6.125%
Subsidiary Issuer [Member] | Note Payable from Public Offering Due 2043 [Member]
Debt Instrument [Line Items]
Total Debt	$ 400,000	400,000
Interest Rate (in hundredths) | Rate	6.20%
Parent Company
Debt Instrument [Line Items]
Commercial Paper	$ 120,000	$ 614,673
Short-term Debt, Weighted Average Interest Rate, at Point in Time | Rate	2.85%	2.23%
Parent Company | Note Payable from Public Offering Due 2028 [Member]
Debt Instrument [Line Items]
Total Debt	$ 800,000
Interest Rate (in hundredths) | Rate	4.55%
Parent Company | Note Payable from Public Offering Due 2048 [Member]
Debt Instrument [Line Items]
Total Debt	$ 450,000
Interest Rate (in hundredths) | Rate	5.20%
Parent Company | Note Payable from Public Offering Due 2022 [Member]
Debt Instrument [Line Items]
Total Debt	$ 547,397	$ 547,397
Interest Rate (in hundredths) | Rate	4.25%
Parent Company | Note Payable Due 2023 [Member]
Debt Instrument [Line Items]
Total Debt	$ 500,000	500,000
Interest Rate (in hundredths) | Rate	7.50%
Parent Company | Note Payable Due 2027 [Member]
Debt Instrument [Line Items]
Total Debt	$ 500,000	500,000
Interest Rate (in hundredths) | Rate	4.00%
Parent Company | Note Payables 1 due 2028 [Member]
Debt Instrument [Line Items]
Total Debt	$ 800,000	0
Interest Rate (in hundredths) | Rate	4.55%
Parent Company | Note Payables 2 due 2028 [Member]
Debt Instrument [Line Items]
Total Debt	$ 100,000	100,000
Interest Rate (in hundredths) | Rate	6.875%
Parent Company | Notes Payables due 2035 [Member]
Debt Instrument [Line Items]
Total Debt	$ 400,000	400,000
Interest Rate (in hundredths) | Rate	6.00%
Parent Company | Notes Payables due 2047 [Member]
Debt Instrument [Line Items]
Total Debt	$ 700,000	700,000
Interest Rate (in hundredths) | Rate	4.95%
Parent Company | Note Payables due 2048 [Member]
Debt Instrument [Line Items]
Total Debt	$ 450,000	$ 0
Interest Rate (in hundredths) | Rate	5.20%

EQUITY (Details)

EQUITY (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended					6 Months Ended	9 Months Ended		12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners									20.00%
Business Combination, Consideration Transferred		$ 195,000
Stock Issued During Period, Shares, New Issues				21,900,000
Share Price				$ 54.50
Proceeds from Sale of Common Stock				$ 1,200,000
Common Stock, Dividends, Per Share, Cash Paid		$ 0.825	$ 0.795	$ 0.77			$ 2.390	$ 1.975
Common Stock, Dividends, Per Share, Declared		$ 0.825			$ 0.745		$ 2.390	$ 1.975
Dividends, Preferred Stock, Cash		$ 300	$ 300	$ 300
Preferred Stock, Dividends, Declared							$ 825	$ 493
Business Acquisition, Description of Acquired Entity						On June 30, 2017, we completed the acquisition of all of the outstanding common units of ONEOK Partners that we did not already own at a fixed exchange ratio of 0.985 of a share of our common stock for each ONEOK Partners common unit. We issued 168.9 million shares of our common stock to third-party common unitholders of ONEOK Partners in exchange for all of the 171.5 million outstanding common units of ONEOK Partners that we previously did not own. As a result of the completion of the Merger Transaction, common units of ONEOK Partners are no longer publicly traded.
Partnership Capital Distributions [Line Items]
General partnership ownership interest						41.20%	100.00%		100.00%
Issued Under Equity Agreement [Member]
Proceeds from Sale of Common Stock									$ 448,300
Common Stock Sold Under Equity Distribution Agreement							0		8,400,000
Series E Preferred Stock [Member]
Preferred Stock, Dividend Rate, Percentage							5.50%
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared	$ 0.855
Dividends Payable, Date of Record	Nov. 5, 2018
Dividends Payable, Date to be Paid	Nov. 14, 2018
Preferred Stock, Dividends, Declared	$ 300
General Partner [Member]
Partnership Capital Distributions [Line Items]
General partnership ownership interest						2.00%
ONEOK [Member]
Aggregate Amount Of Common Shares Available For Issuance And Sale Under Equity Distribution Agreement							$ 1,000,000

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Unrealized gains (losses) on risk management assets/liabilities - January 1			$ (81,915)
Pension and Postretirement Benefit Plan Obligations - January 1			(105,411)
Unrealized gains (losses) on risk-management assets/liabilities of unconsolidated affiliates - January 1			(1,204)
Accumulated other comprehensive loss - January 1			(188,530)
Other Comprehensive Income (Loss) Before Reclassifications, Unrealized Gains (Losses) on Risk-Management Assets/Liabilities			10,729
Other Comprehensive (Income) Loss Before Reclassification, Pension and Postretirement Benefit Plan Obligations			(563)
Other Comprehensive Income (Loss) Before Reclassification, Unrealized Gains (Losses) on Risk-Management Assets/Liabilities of Unconsolidated Affiliates			5,336
Other comprehensive income (loss) before reclassifications			15,502
Other Comprehensive Income (Loss) Reclassification Adjustment from AOCI for Unrealized Gains (Losses) on Risk-Management Assets/Liabilities, Net of Tax	$ 19,261	$ 13,062	43,397	$ 40,272
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Other Comprehensive Income Attributable to Unconsolidated Affiliates, Net of Tax			(55)
Other Comprehensive Income (Loss), Reclassification Adjustment included in Net Income, Net of Tax	22,437	15,152	52,991	28,339
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent			54,126
Other Comprehensive (Income) Loss, Pension and Postretirement Benefit Plans, after Reclassification Adjustment, after Tax	3,236	2,041	9,086	6,122
Other comprehensive income (loss) on investment in unconsolidated affiliates			5,281
Other Comprehensive Income (Loss), Net of Tax	20,451	(5,686)	68,493	43,893
Impact of Adoption of ASU 2018-02 On Unrealized Gains (Losses) on Risk Management Assets/Liabilities			(17,935)
Impact of Adoption of ASU 2018-02 On Pension and Postretirement Benefit Plan Obligations			(20,166)
Impact of Adoption of ASU 2018-02 On Unrealized Gains (Losses) on Risk Management Assets/Liabilities of Unconsolidated Affiliates			0
Impact of Adoption of ASU 2018-02 on AOCI, Total			(38,101)
Unrealized gains (losses) on risk management assets/liabilities - September 30	(45,724)		(45,724)
Pension and Postretirement Benefit Plan Obligations - September 30	(116,491)		(116,491)
Unrealized gains (losses) on risk-management assets/liabilities of unconsolidated affiliates - September 30	4,077		4,077
Accumulated other comprehensive loss - September 30	(158,138)		(158,138)
Reclassification Adjustment from AOCI on Risk Management Assets/Liabilities, Income Tax	5,752	7,671	12,962	13,077
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member]
Other Comprehensive Income (Loss) Reclassification Adjustment from AOCI for Unrealized Gains (Losses) on Risk-Management Assets/Liabilities, Net of Tax	19,261	13,062	43,397	22,126
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Sales [Member] | Commodity Contract [Member]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income	(20,630)	(15,913)	(42,430)	(38,028)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Interest Expense [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income	(4,383)	(4,820)	(13,929)	(15,321)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Total before tax [Member]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income	(25,013)	(20,733)	(56,359)	(53,349)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Tax Expense [Member]
Reclassification Adjustment from AOCI on Risk Management Assets/Liabilities, Income Tax	5,752	7,671	12,962	13,077
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Net of tax [Member]
Other Comprehensive Income (Loss) Reclassification Adjustment from AOCI for Unrealized Gains (Losses) on Risk-Management Assets/Liabilities, Net of Tax	19,261	13,062	43,397	40,272
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Net income attributable to noncontrolling interest [Member]
Reclassification Adjustment from AOCI on Risk Management Assets/Liabilities Net of Tax, Portion Attributable to Noncontrolling Interest	0	0	0	(18,146)
Accumulated Pension and Postretirement Benefit Plans Adjustment Attributable to Parent [Member]
Other Comprehensive (Income) Loss, Pension and Postretirement Benefit Plans, Reclassification Adjustment from AOCI, After Tax	(3,216)	(2,038)	(9,649)	(6,114)
Pension and Postretirement Benefit Plans, Amortization of Gain (Loss)	(4,592)	(3,811)	(13,776)	(11,435)
Pension and Postretirement Benefit Plans, Amortization of Prior Service Cost (Credit)	415	415	1,245	1,245
Reclassification Adjustment from AOCI, before Tax, Pension and Postretirement Benefit Plans, Gain (Loss)	(4,177)	(3,396)	(12,531)	(10,190)
Reclassification Adjustment from AOCI, Tax, Pensions and Postretirement Benefit Plans, Gain (Loss)	961	1,358	2,882	4,076
Accumulated Other Comprehensive Income from Investments in Unconsolidated Affiliates Attributable to Parent [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Other Comprehensive Income Attributable to Unconsolidated Affiliates, Net of Tax	40	(52)	55	(99)
Reclassification Adjustment from AOCI, Before Tax, Portion Attributable to Unconsolidated Affiliates	52	(83)	71	(264)
Reclassification Adjustment from AOCI, Tax, Portion Attributable to Unconsolidated Affiliates	(12)	31	(16)	59
Accumulated Other Comprehensive Income from Investments in Unconsolidated Affiliates Attributable to Parent [Member] | Net of tax [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Other Comprehensive Income Attributable to Unconsolidated Affiliates, Net of Tax	40	(52)	55	(205)
Reclassification Adjustment from AOCI, Net of Tax, Portion Attributable to Unconsolidated Affiliates	$ 0	$ 0	0	(106)
AOCI Attributable to Parent [Member]
Other Comprehensive Income (Loss), Net of Tax			$ 68,493	$ 12,867

EARNINGS PER SHARE EARNINGS P_3

EARNINGS PER SHARE EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic EPS
Net income attributable to ONEOK available for common stock	$ 312,984	$ 165,466	$ 857,990	$ 324,303
Shares	412,117	380,907	411,400	268,108
Earnings per share, basic	$ 0.76	$ 0.43	$ 2.09	$ 1.21
Diluted EPS
Effect of dilutive securities	$ 0	$ 0	$ 0	$ 0
Effect of dilutive securities, number of shares	2,730	2,512	2,635	2,241
Net income attributable to ONEOK available for common stock and common stock equivalents	$ 312,984	$ 165,466	$ 857,990	$ 324,303
Shares	414,847	383,419	414,035	270,349
Earnings per share, diluted	$ 0.75	$ 0.43	$ 2.07	$ 1.20

EMPLOYEE BENEFIT PLANS EMPLOY_3

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Benefits
Components of net periodic benefit cost
Service cost	$ 1,832	$ 1,721	$ 5,496	$ 5,165
Interest cost	4,408	4,655	13,224	13,965
Expected return on plan assets	(5,969)	(5,336)	(17,907)	(16,008)
Amortization of net loss	4,258	3,392	12,774	10,176
Net periodic benefit cost (income)	4,529	4,432	13,587	13,298
Other Postretirement Benefits Plan [Member]
Components of net periodic benefit cost
Service cost	211	165	633	495
Interest cost	527	565	1,581	1,695
Expected return on plan assets	(672)	(564)	(2,016)	(1,692)
Amortization of prior service credit	(415)	(415)	(1,245)	(1,245)
Amortization of net loss	334	419	1,002	1,259
Net periodic benefit cost (income)	$ (15)	$ 170	$ (45)	$ 512

UNCONSOLIDATED AFFILIATES (Deta

UNCONSOLIDATED AFFILIATES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Equity in net earnings (loss) from investments	$ 39,313	$ 40,058	$ 116,070	$ 118,985
Impairment of equity investments	0	(4,270)	0	(4,270)
Accounts Payable, Related Parties, Current	12,600		12,600		$ 13,600
Income Statement [Abstract]
Operating revenues	160,962	163,627	471,641	475,510
Operating expenses	69,004	69,740	205,525	206,141
Net income	85,361	87,330	247,754	260,533
Distributions paid to us	47,197	49,414	145,437	146,094
Unconsolidated Affiliates [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Expenses from Transactions with Related Parties	37,500	39,900	113,200	116,000
Northern Border Pipeline
Schedule of Equity Method Investments [Line Items]
Equity in net earnings (loss) from investments	16,486	16,440	48,863	50,879
Income Statement [Abstract]
Payments to Acquire Equity Method Investments			0	83,000
Overland Pass Pipeline Company
Schedule of Equity Method Investments [Line Items]
Equity in net earnings (loss) from investments	16,081	15,793	48,714	44,243
Roadrunner Gas Transmission
Schedule of Equity Method Investments [Line Items]
Equity in net earnings (loss) from investments	6,303	4,898	16,803	14,192
Income Statement [Abstract]
Payments to Acquire Equity Method Investments			500	4,000
Other Unconsolidated Affiliates
Schedule of Equity Method Investments [Line Items]
Equity in net earnings (loss) from investments	$ 443	$ 2,927	$ 1,690	$ 9,671

REVENUE REVENUE (Details)

REVENUE REVENUE (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings increase	$ 0		$ 0			$ 0
Commodity sales	3,083,625,000	$ 2,322,534,000	8,578,891,000	$ 6,700,260,000
Services revenue	310,265,000	583,832,000	877,605,000	1,681,489,000
Cost of sales and fuel (exclusive of depreciation and operating costs)	2,560,765,000	2,229,416,000	7,104,609,000	6,464,281,000
Depreciation and amortization	107,383,000	102,298,000	317,908,000	302,566,000
Income taxes	102,983,000	97,128,000	266,285,000	195,913,000
Net income	313,916,000	166,531,000	862,144,000	528,707,000
Net income attributable to noncontrolling interest	657,000	789,000	3,329,000	203,911,000
Net income attributable to ONEOK	313,259,000	$ 165,742,000	858,815,000	$ 324,796,000
Accounts receivable, net	1,085,075,000		1,085,075,000			1,202,951,000
Natural gas and natural gas liquids in storage	426,293,000		426,293,000			342,293,000
Other assets, current	61,340,000		61,340,000			53,008,000
Property, plant and equipment	17,120,187,000		17,120,187,000			15,559,667,000
Accumulated depreciation and amortization	3,159,660,000		3,159,660,000			2,861,541,000
Other assets	191,170,000		191,170,000			180,830,000
Accounts payable	1,339,507,000		1,339,507,000			1,140,571,000
Other current liabilities	208,312,000		208,312,000			179,971,000
Deferred income taxes	132,242,000		132,242,000			52,697,000
Other deferred credits	350,400,000		350,400,000			348,924,000
Retained earnings/paid-in capital	7,662,673,000		7,662,673,000			6,588,878,000
Noncontrolling interests in consolidated subsidiaries	0		0			157,485,000
Contract with Customer, Asset and Liability [Abstract]
Accounts receivable, net	1,077,700,000		1,077,700,000			$ 1,200,000,000
Contract with customer, asset	7,700,000		7,700,000		$ 6,400,000
Amounts invoiced in excess of revenue recognized	700,000		700,000
Net additions	2,000,000		2,000,000
Contract with customer, asset, net, current	2,900,000		2,900,000		900,000
Contract with customer, asset, net, noncurrent	4,800,000		4,800,000
Contract with customer, liability	38,300,000		38,300,000		33,300,000
Revenue recognized included in beginning balance			(19,000,000)
Net additions	24,000,000		24,000,000
Contract with customer, liability, current	23,800,000		23,800,000		19,500,000
Contract with customer, liability, noncurrent	14,500,000		14,500,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	1,960,100,000		1,960,100,000
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Commodity sales	3,129,947,000		8,625,213,000
Services revenue	707,633,000		1,986,563,000
Cost of sales and fuel (exclusive of depreciation and operating costs)	3,005,767,000		8,255,457,000
Depreciation and amortization	107,238,000		317,472,000
Income taxes	102,714,000		267,404,000
Net income	313,018,000		865,893,000
Net income attributable to noncontrolling interest	655,000		3,322,000
Net income attributable to ONEOK	312,363,000		862,571,000
Accounts receivable, net	1,214,627,000		1,214,627,000
Natural gas and natural gas liquids in storage	439,035,000		439,035,000
Other assets, current	60,198,000		60,198,000
Property, plant and equipment	17,098,053,000		17,098,053,000
Accumulated depreciation and amortization	3,157,852,000		3,157,852,000
Other assets	186,417,000		186,417,000
Accounts payable	1,469,059,000		1,469,059,000
Other current liabilities	206,658,000		206,658,000
Deferred income taxes	132,859,000		132,859,000
Other deferred credits	335,909,000		335,909,000
Retained earnings/paid-in capital	7,664,722,000		7,664,722,000
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Commodity sales	(46,322,000)		(46,322,000)
Services revenue	(397,368,000)		(1,108,958,000)
Cost of sales and fuel (exclusive of depreciation and operating costs)	(445,002,000)		(1,150,848,000)
Depreciation and amortization	145,000		436,000
Income taxes	269,000		(1,119,000)
Net income	898,000		(3,749,000)
Net income attributable to noncontrolling interest	2,000		7,000
Net income attributable to ONEOK	896,000		(3,756,000)
Accounts receivable, net	(129,552,000)		(129,552,000)
Natural gas and natural gas liquids in storage	(12,742,000)		(12,742,000)
Other assets, current	1,142,000		1,142,000
Property, plant and equipment	22,134,000		22,134,000
Accumulated depreciation and amortization	1,808,000		1,808,000
Other assets	4,753,000		4,753,000
Accounts payable	(129,552,000)		(129,552,000)
Other current liabilities	1,654,000		1,654,000
Deferred income taxes	(617,000)		(617,000)
Other deferred credits	14,491,000		14,491,000
Retained earnings/paid-in capital	(2,049,000)		(2,049,000)
2018 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	90,500,000		90,500,000
2019 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	296,200,000		296,200,000
2020 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	245,100,000		245,100,000
2021 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	237,400,000		237,400,000
Thereafter [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation	$ 1,090,900,000		$ 1,090,900,000
Retained Earnings
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Retained earnings increase					$ 1,700,000

SEGMENTS (Details)

SEGMENTS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment disclosure [Abstract]
Revenues	$ 3,393,890	$ 2,906,366	$ 9,456,496	$ 8,381,749
Cost of sales and fuel (exclusive of depreciation and operating costs)	(2,560,765)	(2,229,416)	(7,104,609)	(6,464,281)
Operating costs	(230,371)	(204,334)	(670,728)	(608,627)
Equity in net earnings (loss) from investments	39,313	40,058	116,070	118,985
Depreciation and amortization	(107,383)	(102,298)	(317,908)	(302,566)
Total assets	17,911,314	16,764,841	17,911,314	16,764,841	$ 16,845,937
Capital expenditures	694,303	135,199	1,309,655	330,431
Net income	313,916	166,531	862,144	528,707
Interest expense, net of capitalized interest	121,910	126,533	351,131	361,468
Income taxes	102,983	97,128	266,285	195,913
Impairment charges	0	(20,240)	0	(20,240)
Noncash compensation expense	5,829	4,883	27,195	9,790
Other corporate costs and noncash items	(3,290)	5,783	(5,384)	52,096
Noncash Contribution Expense			0	12,600
Business Combination, Acquisition Related Costs				29,500
Series E Preferred Stock [Member]
Segment disclosure [Abstract]
Noncash Contribution Expense				20,000
Natural Gas Gathering And Processing [Member]
Segment disclosure [Abstract]
Revenues	791,255	782,928	2,200,175	2,130,019
Cost of sales and fuel (exclusive of depreciation and operating costs)	(542,463)	(566,988)	(1,478,044)	(1,544,263)
Operating costs	(90,970)	(79,559)	(272,931)	(223,546)
Equity in net earnings (loss) from investments	74	3,433	948	9,843
Noncash compensation expense and other	1,703	2,136	6,868	2,125
Segment adjusted EBITDA	159,599	141,950	457,016	374,178
Depreciation and amortization	(49,223)	(46,842)	(145,120)	(137,843)
Total assets	5,811,140	5,385,778	5,811,140	5,385,778
Capital expenditures	213,034	85,542	433,605	185,713
Impairment charges		(20,240)		(20,240)
Natural Gas Gathering And Processing [Member] | Natural Gas Gathering and Processing Intersegment [Member]
Segment disclosure [Abstract]
Revenues	519,700		1,366,000
Natural Gas Liquids [Member]
Segment disclosure [Abstract]
Revenues	3,026,288	2,501,979	8,332,687	7,243,648
Cost of sales and fuel (exclusive of depreciation and operating costs)	(2,544,854)	(2,136,207)	(7,009,438)	(6,188,501)
Operating costs	(101,126)	(89,803)	(289,328)	(255,220)
Equity in net earnings (loss) from investments	16,450	15,287	49,456	44,071
Noncash compensation expense and other	2,268	2,663	9,789	1,459
Segment adjusted EBITDA	399,026	293,919	1,093,166	845,457
Depreciation and amortization	(43,688)	(41,929)	(128,993)	(124,471)
Total assets	9,632,212	8,515,535	9,632,212	8,515,535
Capital expenditures	444,780	27,024	786,635	59,813
Impairment charges		0		0
Natural Gas Liquids [Member] | Natural Gas Liquids Intersegment [Member]
Segment disclosure [Abstract]
Revenues	7,400		20,100
Natural Gas Liquids [Member] | Natural Gas Liquids Regulated [Member]
Segment disclosure [Abstract]
Revenues	316,000	293,100	910,300	878,800
Cost of sales and fuel (exclusive of depreciation and operating costs)	(132,700)	(124,200)	(379,500)	(359,600)
Natural Gas Pipelines [Member]
Segment disclosure [Abstract]
Revenues	105,194	106,438	314,897	311,105
Cost of sales and fuel (exclusive of depreciation and operating costs)	(2,384)	(10,614)	(10,475)	(33,990)
Operating costs	(36,543)	(29,568)	(104,692)	(91,813)
Equity in net earnings (loss) from investments	22,789	21,338	65,666	65,071
Noncash compensation expense and other	1,050	(67)	3,701	772
Segment adjusted EBITDA	90,106	87,527	269,097	251,145
Depreciation and amortization	(13,625)	(12,765)	(41,320)	(37,906)
Total assets	2,109,897	2,040,445	2,109,897	2,040,445
Capital expenditures	31,522	18,811	71,897	70,671
Impairment charges		0		0
Natural Gas Pipelines [Member] | Natural Gas Pipelines Intersegment [Member]
Segment disclosure [Abstract]
Revenues	2,400		7,000
Natural Gas Pipelines [Member] | Natural Gas Pipelines Regulated [Member]
Segment disclosure [Abstract]
Revenues	65,900	65,600	198,400	197,300
Cost of sales and fuel (exclusive of depreciation and operating costs)	(5,500)	(10,500)	(20,400)	(32,900)
Total Segments [Member]
Segment disclosure [Abstract]
Revenues	3,922,737	3,391,345	10,847,759	9,684,772
Cost of sales and fuel (exclusive of depreciation and operating costs)	(3,089,701)	(2,713,809)	(8,497,957)	(7,766,754)
Operating costs	(228,639)	(198,930)	(666,951)	(570,579)
Equity in net earnings (loss) from investments	39,313	40,058	116,070	118,985
Noncash compensation expense and other	5,021	4,732	20,358	4,356
Segment adjusted EBITDA	648,731	523,396	1,819,279	1,470,780
Depreciation and amortization	(106,536)	(101,536)	(315,433)	(300,220)
Total assets	17,553,249	15,941,758	17,553,249	15,941,758
Capital expenditures	689,336	131,377	1,292,137	316,197
Impairment charges		(20,240)		(20,240)
Other and Eliminations
Segment disclosure [Abstract]
Revenues	(528,847)	(484,979)	(1,391,263)	(1,303,023)
Cost of sales and fuel (exclusive of depreciation and operating costs)	528,936	484,393	1,393,348	1,302,473
Operating costs	(1,732)	(5,404)	(3,777)	(38,048)
Equity in net earnings (loss) from investments	0	0	0	0
Depreciation and amortization	(847)	(762)	(2,475)	(2,346)
Total assets	358,065	823,083	358,065	823,083
Capital expenditures	4,967	3,822	17,518	14,234
Impairment charges		0		0
Unaffiliated entity [Member]
Segment disclosure [Abstract]
Revenues		2,906,366		8,381,749
Unaffiliated entity [Member] | Natural Gas Gathering And Processing [Member]
Segment disclosure [Abstract]
Revenues		453,432		1,286,669
Unaffiliated entity [Member] | Natural Gas Liquids [Member]
Segment disclosure [Abstract]
Revenues		2,348,052		6,788,451
Unaffiliated entity [Member] | Natural Gas Pipelines [Member]
Segment disclosure [Abstract]
Revenues		104,340		305,019
Unaffiliated entity [Member] | Total Segments [Member]
Segment disclosure [Abstract]
Revenues		2,905,824		8,380,139
Unaffiliated entity [Member] | Other and Eliminations
Segment disclosure [Abstract]
Revenues		542		1,610
Operating Segments [Member]
Segment disclosure [Abstract]
Revenues		0		0
Operating Segments [Member] | Natural Gas Gathering And Processing [Member]
Segment disclosure [Abstract]
Revenues		329,496		843,350
Operating Segments [Member] | Natural Gas Liquids [Member]
Segment disclosure [Abstract]
Revenues		153,927		455,197
Operating Segments [Member] | Natural Gas Liquids [Member] | Natural Gas Liquids Regulated [Member]
Segment disclosure [Abstract]
Revenues	276,400	250,200	784,800	752,500
Operating Segments [Member] | Natural Gas Pipelines [Member]
Segment disclosure [Abstract]
Revenues		2,098		6,086
Operating Segments [Member] | Total Segments [Member]
Segment disclosure [Abstract]
Revenues		485,521		1,304,633
Operating Segments [Member] | Other and Eliminations
Segment disclosure [Abstract]
Revenues		$ (485,521)		$ (1,304,633)
Noncustomer [Domain]
Segment disclosure [Abstract]
Revenues	(17,700)		(32,100)
NGL and Condensate Sales [Member]
Segment disclosure [Abstract]
Revenues	2,836,661		7,862,478
NGL and Condensate Sales [Member] | Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	501,163		1,362,159
NGL and Condensate Sales [Member] | Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,861,896		7,884,183
NGL and Condensate Sales [Member] | Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
NGL and Condensate Sales [Member] | Total Segments [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3,363,059		9,246,342
NGL and Condensate Sales [Member] | Other and Eliminations
Segment disclosure [Abstract]
Revenues	(526,398)		(1,383,864)
Residue Natural Gas Sales [Member]
Segment disclosure [Abstract]
Revenues	246,237		714,172
Residue Natural Gas Sales [Member] | Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	245,474		709,089
Residue Natural Gas Sales [Member] | Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
Residue Natural Gas Sales [Member] | Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	763		5,861
Residue Natural Gas Sales [Member] | Total Segments [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	246,237		714,950
Residue Natural Gas Sales [Member] | Other and Eliminations
Segment disclosure [Abstract]
Revenues	0		(778)
Gathering and Exchange Services Revenue [Member]
Segment disclosure [Abstract]
Revenues	157,934		418,871
Gathering and Exchange Services Revenue [Member] | Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	41,101		122,331
Gathering and Exchange Services Revenue [Member] | Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	116,833		296,561
Gathering and Exchange Services Revenue [Member] | Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
Gathering and Exchange Services Revenue [Member] | Total Segments [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	157,934		418,892
Gathering and Exchange Services Revenue [Member] | Other and Eliminations
Segment disclosure [Abstract]
Revenues	0		(21)
Transportation and Storage Revenue [Member]
Segment disclosure [Abstract]
Revenues	140,912		426,428
Transportation and Storage Revenue [Member] | Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0		0
Transportation and Storage Revenue [Member] | Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	45,251		143,741
Transportation and Storage Revenue [Member] | Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	98,031		289,646
Transportation and Storage Revenue [Member] | Total Segments [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	143,282		433,387
Transportation and Storage Revenue [Member] | Other and Eliminations
Segment disclosure [Abstract]
Revenues	(2,370)		(6,959)
Other [Member]
Segment disclosure [Abstract]
Revenues	12,146		34,547
Other [Member] | Natural Gas Gathering And Processing [Member]
Segment disclosure [Abstract]
Revenues	3,517		6,596
Other [Member] | Natural Gas Liquids [Member]
Segment disclosure [Abstract]
Revenues	2,308		8,202
Other [Member] | Natural Gas Pipelines [Member]
Segment disclosure [Abstract]
Revenues	6,400		19,390
Other [Member] | Total Segments [Member]
Segment disclosure [Abstract]
Revenues	12,225		34,188
Other [Member] | Other and Eliminations
Segment disclosure [Abstract]
Revenues	$ (79)		$ 359

SUPPLEMENTAL CONDENSED CONSOL_3

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Commodity sales	$ 3,083,625	$ 2,322,534	$ 8,578,891	$ 6,700,260
Services	310,265	583,832	877,605	1,681,489
Total revenues	3,393,890	2,906,366	9,456,496	8,381,749
Cost of sales and fuel (exclusive of items shown separately below)	2,560,765	2,229,416	7,104,609	6,464,281
Impairment of long-lived assets	0	15,970	0	15,970
Gain on sale of assets	(163)	(274)	(348)	(904)
Operating income	495,534	354,622	1,363,599	991,209
Equity in net earnings (loss) from investments	39,313	40,058	116,070	118,985
Impairment of equity investments	0	(4,270)	0	(4,270)
Interest expense, net	(121,910)	(126,533)	(351,131)	(361,468)
Income before income taxes	416,899	263,659	1,128,429	724,620
Income taxes	(102,983)	(97,128)	(266,285)	(195,913)
Net income	313,916	166,531	862,144	528,707
Less: Net income attributable to noncontrolling interests	657	789	3,329	203,911
Net income attributable to ONEOK	313,259	165,742	858,815	324,796
Less: Preferred stock dividends	275	276	825	493
Net income available to common shareholders	$ 312,984	165,466	$ 857,990	324,303
Northern Border Pipeline
Condensed Financial Statements, Captions [Line Items]
Equity Method Investment, Ownership Percentage	50.00%		50.00%
Equity in net earnings (loss) from investments	$ 16,486	16,440	$ 48,863	50,879
Reportable Legal Entities | Parent Issuer & Guarantor
Condensed Financial Statements, Captions [Line Items]
Commodity sales	0	0	0	0
Services	0	0	0	0
Total revenues	0	0	0	0
Cost of sales and fuel (exclusive of items shown separately below)	0	0	0	0
Operating expenses	2,000	1,200	3,300	25,900
Impairment of long-lived assets		0		0
Gain on sale of assets	0	0	0	0
Operating income	(2,000)	(1,200)	(3,300)	(25,900)
Equity in net earnings (loss) from investments	457,300	298,000	1,226,600	842,000
Impairment of equity investments		0		0
Other income (expense), net	9,300	4,100	23,100	(15,500)
Interest expense, net	(49,100)	(43,200)	(129,200)	(93,500)
Income before income taxes	415,500	257,700	1,117,200	707,100
Income taxes	(102,300)	(91,900)	(258,400)	(180,900)
Net income	313,200	165,800	858,800	526,200
Less: Net income attributable to noncontrolling interests	0	100	0	201,400
Net income attributable to ONEOK	313,200	165,700	858,800	324,800
Less: Preferred stock dividends	200	200	800	500
Net income available to common shareholders	313,000	165,500	858,000	324,300
Reportable Legal Entities | Subsidiary Issuer & Guarantor
Condensed Financial Statements, Captions [Line Items]
Commodity sales	0	0	0	0
Services	0	0	0	0
Total revenues	0	0	0	0
Cost of sales and fuel (exclusive of items shown separately below)	0	0	0	0
Operating expenses	0	0	0	0
Impairment of long-lived assets		0		0
Gain on sale of assets	0	0	0	0
Operating income	0	0	0	0
Equity in net earnings (loss) from investments	457,100	298,300	1,231,200	845,900
Impairment of equity investments		0		0
Other income (expense), net	80,300	86,100	234,900	272,200
Interest expense, net	(80,300)	(86,100)	(234,900)	(272,200)
Income before income taxes	457,100	298,300	1,231,200	845,900
Income taxes	0	0	0	0
Net income	457,100	298,300	1,231,200	845,900
Less: Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to ONEOK	457,100	298,300	1,231,200	845,900
Less: Preferred stock dividends	0	0	0	0
Net income available to common shareholders	457,100	298,300	1,231,200	845,900
Reportable Legal Entities | Guarantor Subsidiary
Condensed Financial Statements, Captions [Line Items]
Commodity sales	0	0	0	0
Services	0	0	0	0
Total revenues	0	0	0	0
Cost of sales and fuel (exclusive of items shown separately below)	0	0	0	0
Operating expenses	0	2,600	0	8,800
Impairment of long-lived assets		0		0
Gain on sale of assets	0	0	0	0
Operating income	0	(2,600)	0	(8,800)
Equity in net earnings (loss) from investments	457,100	300,900	1,231,200	854,700
Impairment of equity investments		0		0
Other income (expense), net	80,300	86,100	234,900	272,200
Interest expense, net	(80,300)	(86,100)	(234,900)	(272,200)
Income before income taxes	457,100	298,300	1,231,200	845,900
Income taxes	0	0	0	0
Net income	457,100	298,300	1,231,200	845,900
Less: Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to ONEOK	457,100	298,300	1,231,200	845,900
Less: Preferred stock dividends	0	0	0	0
Net income available to common shareholders	457,100	298,300	1,231,200	845,900
Reportable Legal Entities | Combined Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Commodity sales	3,083,600	2,322,500	8,578,900	6,700,300
Services	310,800	584,300	879,100	1,683,000
Total revenues	3,394,400	2,906,800	9,458,000	8,383,300
Cost of sales and fuel (exclusive of items shown separately below)	2,560,800	2,229,400	7,104,600	6,464,300
Operating expenses	336,300	303,300	986,800	878,000
Impairment of long-lived assets		16,000		16,000
Gain on sale of assets	(200)	(300)	(300)	(900)
Operating income	497,500	358,400	1,366,900	1,025,900
Equity in net earnings (loss) from investments	30,100	27,600	86,200	72,100
Impairment of equity investments		(4,300)		(4,300)
Other income (expense), net	(5,300)	(4,300)	(23,300)	(4,300)
Interest expense, net	(72,800)	(83,300)	(221,900)	(268,000)
Income before income taxes	449,500	294,100	1,207,900	821,400
Income taxes	(700)	(5,300)	(7,900)	(15,000)
Net income	448,800	288,800	1,200,000	806,400
Less: Net income attributable to noncontrolling interests	700	700	3,300	2,500
Net income attributable to ONEOK	448,100	288,100	1,196,700	803,900
Less: Preferred stock dividends	0	0	0	0
Net income available to common shareholders	448,100	288,100	1,196,700	803,900
Reportable Legal Entities | Total
Condensed Financial Statements, Captions [Line Items]
Commodity sales	3,083,600	2,322,500	8,578,900	6,700,300
Services	310,300	583,800	877,600	1,681,500
Total revenues	3,393,900	2,906,300	9,456,500	8,381,800
Cost of sales and fuel (exclusive of items shown separately below)	2,560,800	2,229,400	7,104,600	6,464,300
Operating expenses	337,800	306,600	988,600	911,200
Impairment of long-lived assets		16,000		16,000
Gain on sale of assets	(200)	(300)	(300)	(900)
Operating income	495,500	354,600	1,363,600	991,200
Equity in net earnings (loss) from investments	39,300	40,100	116,100	119,000
Impairment of equity investments		(4,300)		(4,300)
Other income (expense), net	4,000	(200)	(200)	(19,800)
Interest expense, net	(121,900)	(126,500)	(351,100)	(361,500)
Income before income taxes	416,900	263,700	1,128,400	724,600
Income taxes	(103,000)	(97,200)	(266,300)	(195,900)
Net income	313,900	166,500	862,100	528,700
Less: Net income attributable to noncontrolling interests	700	800	3,300	203,900
Net income attributable to ONEOK	313,200	165,700	858,800	324,800
Less: Preferred stock dividends	200	200	800	500
Net income available to common shareholders	313,000	165,500	858,000	324,300
Consolidating Entries
Condensed Financial Statements, Captions [Line Items]
Commodity sales	0	0	0	0
Services	(500)	(500)	(1,500)	(1,500)
Total revenues	(500)	(500)	(1,500)	(1,500)
Cost of sales and fuel (exclusive of items shown separately below)	0	0	0	0
Operating expenses	(500)	(500)	(1,500)	(1,500)
Impairment of long-lived assets		0		0
Gain on sale of assets	0	0	0	0
Operating income	0	0	0	0
Equity in net earnings (loss) from investments	(1,362,300)	(884,700)	(3,659,100)	(2,495,700)
Impairment of equity investments		0		0
Other income (expense), net	(160,600)	(172,200)	(469,800)	(544,400)
Interest expense, net	160,600	172,200	469,800	544,400
Income before income taxes	(1,362,300)	(884,700)	(3,659,100)	(2,495,700)
Income taxes	0	0	0	0
Net income	(1,362,300)	(884,700)	(3,659,100)	(2,495,700)
Less: Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to ONEOK	(1,362,300)	(884,700)	(3,659,100)	(2,495,700)
Less: Preferred stock dividends	0	0	0	0
Net income available to common shareholders	$ (1,362,300)	$ (884,700)	$ (3,659,100)	$ (2,495,700)

SUPPLEMENTAL CONDENSED CONSOL_4

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net income	$ 313,916	$ 166,531	$ 862,144	$ 528,707
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	(3,526)	(20,620)	10,729	(1,287)
Realized (gains) losses on derivatives in net income, net of tax	(19,261)	(13,062)	(43,397)	(40,272)
Change in pension and postretirement benefit plan liability, net of tax	(3,236)	(2,041)	(9,086)	(6,122)
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	1,480	(169)	5,281	(1,214)
Total other comprehensive income (loss), net of tax	20,451	(5,686)	68,493	43,893
Comprehensive income	334,367	160,845	930,637	572,600
Less: Comprehensive income attributable to noncontrolling interests	657	789	3,329	234,937
Comprehensive income attributable to ONEOK	333,710	160,056	927,308	337,663
Reportable Legal Entities | Parent Issuer & Guarantor
Condensed Financial Statements, Captions [Line Items]
Net income	313,200	165,800	858,800	526,200
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	20,200	18,400	54,000	18,100
Realized (gains) losses on derivatives in net income, net of tax	0	600	1,900	1,600
Change in pension and postretirement benefit plan liability, net of tax	3,200	2,000	9,700	6,100
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	0	0	0	0
Total other comprehensive income (loss), net of tax	23,400	21,000	65,600	25,800
Comprehensive income	336,600	186,800	924,400	552,000
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	232,400
Comprehensive income attributable to ONEOK	336,600	186,800	924,400	319,600
Reportable Legal Entities | Subsidiary Issuer & Guarantor
Condensed Financial Statements, Captions [Line Items]
Net income	457,100	298,300	1,231,200	845,900
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	(30,700)	(61,900)	(56,200)	(38,800)
Realized (gains) losses on derivatives in net income, net of tax	25,000	19,800	53,900	50,700
Change in pension and postretirement benefit plan liability, net of tax	0	0	(600)	0
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	2,000	(300)	6,900	(1,500)
Total other comprehensive income (loss), net of tax	(3,700)	(42,400)	4,000	10,400
Comprehensive income	453,400	255,900	1,235,200	856,300
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to ONEOK	453,400	255,900	1,235,200	856,300
Reportable Legal Entities | Guarantor Subsidiary
Condensed Financial Statements, Captions [Line Items]
Net income	457,100	298,300	1,231,200	845,900
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	(30,700)	(42,400)	(56,200)	(6,100)
Realized (gains) losses on derivatives in net income, net of tax	20,600	15,900	42,400	38,000
Change in pension and postretirement benefit plan liability, net of tax	0	0	0	0
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	2,000	(300)	6,900	(1,500)
Total other comprehensive income (loss), net of tax	(8,100)	(26,800)	(6,900)	30,400
Comprehensive income	449,000	271,500	1,224,300	876,300
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to ONEOK	449,000	271,500	1,224,300	876,300
Reportable Legal Entities | Combined Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income	448,800	288,800	1,200,000	806,400
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	(23,700)	(19,500)	(43,300)	13,300
Realized (gains) losses on derivatives in net income, net of tax	14,900	8,600	30,000	26,000
Change in pension and postretirement benefit plan liability, net of tax	0	0	0	0
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	1,500	(200)	5,300	(1,200)
Total other comprehensive income (loss), net of tax	(7,300)	(11,100)	(8,000)	38,100
Comprehensive income	441,500	277,700	1,192,000	844,500
Less: Comprehensive income attributable to noncontrolling interests	700	700	3,300	2,500
Comprehensive income attributable to ONEOK	440,800	277,000	1,188,700	842,000
Reportable Legal Entities | Total
Condensed Financial Statements, Captions [Line Items]
Net income	313,900	166,500	862,100	528,700
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	(3,500)	(20,600)	10,700	(1,300)
Realized (gains) losses on derivatives in net income, net of tax	19,300	13,100	43,400	40,300
Change in pension and postretirement benefit plan liability, net of tax	3,200	2,000	9,100	6,100
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	1,500	(200)	5,300	(1,200)
Total other comprehensive income (loss), net of tax	20,500	(5,700)	68,500	43,900
Comprehensive income	334,400	160,800	930,600	572,600
Less: Comprehensive income attributable to noncontrolling interests	700	700	3,300	234,900
Comprehensive income attributable to ONEOK	333,700	160,100	927,300	337,700
Consolidating Entries
Condensed Financial Statements, Captions [Line Items]
Net income	(1,362,300)	(884,700)	(3,659,100)	(2,495,700)
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	61,400	84,800	112,400	12,200
Realized (gains) losses on derivatives in net income, net of tax	(41,200)	(31,800)	(84,800)	(76,000)
Change in pension and postretirement benefit plan liability, net of tax	0	0	0	0
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	(4,000)	600	(13,800)	3,000
Total other comprehensive income (loss), net of tax	16,200	53,600	13,800	(60,800)
Comprehensive income	(1,346,100)	(831,100)	(3,645,300)	(2,556,500)
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to ONEOK	$ (1,346,100)	$ (831,100)	$ (3,645,300)	$ (2,556,500)

SUPPLEMENTAL CONDENSED CONSOL_5

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 84,464	$ 37,193	$ 11,676	$ 248,875
Accounts receivable, net	1,085,075	1,202,951
Materials and supplies	128,574	90,301
Natural gas and natural gas liquids in storage	426,293	342,293
Other current assets	61,340	53,008
Total current assets	1,807,908	1,764,458
Property, plant and equipment
Property, plant and equipment	17,120,187	15,559,667
Accumulated depreciation and amortization	3,159,660	2,861,541
Net property, plant and equipment	13,960,527	12,698,126
Investments and other assets
Investments	981,592	1,003,156
Goodwill and intangible assets	970,117	993,460
Other assets	191,170	180,830
Total investments and other assets	2,142,879	2,383,353
Total assets	17,911,314	16,845,937	16,764,841
Current liabilities
Current maturities of long-term debt	507,650	432,650
Short-term borrowings	120,000	614,673
Accounts payable	1,339,507	1,140,571
Other current liabilities	208,312	179,971
Total current liabilities	2,450,206	2,667,335
Long-term debt, excluding current maturities	8,325,708	8,091,629
Deferred credits and other liabilities
Deferred income taxes	132,242	52,697
Other deferred credits	350,400	348,924
Total deferred credits and other liabilities	482,642	401,621
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries	6,652,758	5,527,867
Noncontrolling interests in consolidated subsidiaries	0	157,485
Total equity	6,652,758	5,685,352	5,516,383	3,428,915
Total liabilities and equity	17,911,314	16,845,937
Reportable Legal Entities | Parent Issuer & Guarantor
Current assets
Cash and cash equivalents	84,500	37,200	11,700	248,500
Accounts receivable, net	0	0
Materials and supplies	0	0
Natural gas and natural gas liquids in storage	0	0
Other current assets	10,400	9,800
Total current assets	94,900	47,000
Property, plant and equipment
Property, plant and equipment	141,000	128,300
Accumulated depreciation and amortization	90,500	86,400
Net property, plant and equipment	50,500	41,900
Investments and other assets
Investments	5,977,500	5,752,100
Intercompany notes receivable	4,769,100	2,926,900
Other assets	174,300	416,900
Total investments and other assets	10,920,900	9,095,900
Total assets	11,066,300	9,184,800
Current liabilities
Current maturities of long-term debt	0	0
Short-term borrowings	120,000	614,700
Accounts payable	5,100	12,000
Other current liabilities	71,800	65,900
Total current liabilities	196,900	692,600
Intercompany debt	0	0
Long-term debt, excluding current maturities	3,962,200	2,726,400
Deferred credits and other liabilities
Deferred income taxes	25,800	0
Other deferred credits	228,600	237,900
Total deferred credits and other liabilities	254,400	237,900
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries		5,527,900
Noncontrolling interests in consolidated subsidiaries		0
Total equity	6,652,800	5,527,900
Total liabilities and equity	11,066,300	9,184,800
Reportable Legal Entities | Subsidiary Issuer & Guarantor
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Materials and supplies	0	0
Natural gas and natural gas liquids in storage	0	0
Other current assets	0	1,300
Total current assets	0	1,300
Property, plant and equipment
Property, plant and equipment	0	0
Accumulated depreciation and amortization	0	0
Net property, plant and equipment	0	0
Investments and other assets
Investments	3,359,000	3,133,700
Intercompany notes receivable	7,682,500	8,627,800
Other assets	0	200
Total investments and other assets	11,041,500	11,761,700
Total assets	11,041,500	11,763,000
Current liabilities
Current maturities of long-term debt	500,000	425,000
Short-term borrowings	0	0
Accounts payable	0	0
Other current liabilities	67,600	85,000
Total current liabilities	567,600	510,000
Intercompany debt	0	0
Long-term debt, excluding current maturities	4,340,400	5,336,400
Deferred credits and other liabilities
Deferred income taxes	0	0
Other deferred credits	0	0
Total deferred credits and other liabilities	0	0
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries		5,916,600
Noncontrolling interests in consolidated subsidiaries		0
Total equity	6,133,500	5,916,600
Total liabilities and equity	11,041,500	11,763,000
Reportable Legal Entities | Guarantor Subsidiary
Current assets
Cash and cash equivalents	0	0	0	400
Accounts receivable, net	0	0
Materials and supplies	0	0
Natural gas and natural gas liquids in storage	0	0
Other current assets	0	0
Total current assets	0	0
Property, plant and equipment
Property, plant and equipment	0	0
Accumulated depreciation and amortization	0	0
Net property, plant and equipment	0	0
Investments and other assets
Investments	9,223,200	8,058,400
Intercompany notes receivable	1,818,300	3,703,100
Other assets	0	0
Total investments and other assets	11,041,500	11,761,500
Total assets	11,041,500	11,761,500
Current liabilities
Current maturities of long-term debt	0	0
Short-term borrowings	0	0
Accounts payable	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Intercompany debt	7,682,500	8,627,800
Long-term debt, excluding current maturities	0	0
Deferred credits and other liabilities
Deferred income taxes	0	0
Other deferred credits	0	0
Total deferred credits and other liabilities	0	0
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries		3,133,700
Noncontrolling interests in consolidated subsidiaries		0
Total equity	3,359,000	3,133,700
Total liabilities and equity	11,041,500	11,761,500
Reportable Legal Entities | Combined Non-Guarantor Subsidiaries
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	1,085,100	1,203,000
Materials and supplies	128,600	90,300
Natural gas and natural gas liquids in storage	426,300	342,300
Other current assets	73,000	80,600
Total current assets	1,713,000	1,716,200
Property, plant and equipment
Property, plant and equipment	16,979,200	15,431,300
Accumulated depreciation and amortization	3,069,200	2,775,100
Net property, plant and equipment	13,910,000	12,656,200
Investments and other assets
Investments	796,800	803,000
Intercompany notes receivable	0	0
Other assets	988,200	1,007,400
Total investments and other assets	1,785,000	1,810,400
Total assets	17,408,000	16,182,800
Current liabilities
Current maturities of long-term debt	7,700	7,700
Short-term borrowings	0	0
Accounts payable	1,334,400	1,128,600
Other current liabilities	343,600	328,400
Total current liabilities	1,685,700	1,464,700
Intercompany debt	6,587,400	6,630,000
Long-term debt, excluding current maturities	23,100	28,800
Deferred credits and other liabilities
Deferred income taxes	107,600	97,100
Other deferred credits	121,800	111,000
Total deferred credits and other liabilities	229,400	208,100
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries		7,693,700
Noncontrolling interests in consolidated subsidiaries		157,500
Total equity	8,882,400	7,851,200
Total liabilities and equity	17,408,000	16,182,800
Reportable Legal Entities | Total
Current assets
Cash and cash equivalents	84,500	37,200	11,700	248,900
Accounts receivable, net	1,085,100	1,203,000
Materials and supplies	128,600	90,300
Natural gas and natural gas liquids in storage	426,300	342,300
Other current assets	83,400	91,700
Total current assets	1,807,900	1,764,500
Property, plant and equipment
Property, plant and equipment	17,120,200	15,559,600
Accumulated depreciation and amortization	3,159,700	2,861,500
Net property, plant and equipment	13,960,500	12,698,100
Investments and other assets
Investments	981,600	1,003,200
Intercompany notes receivable	0	0
Other assets	1,161,300	1,380,100
Total investments and other assets	2,142,900	2,383,300
Total assets	17,911,300	16,845,900
Current liabilities
Current maturities of long-term debt	507,700	432,700
Short-term borrowings	120,000	614,700
Accounts payable	1,339,500	1,140,600
Other current liabilities	483,000	479,300
Total current liabilities	2,450,200	2,667,300
Intercompany debt	0	0
Long-term debt, excluding current maturities	8,325,700	8,091,600
Deferred credits and other liabilities
Deferred income taxes	132,200	52,700
Other deferred credits	350,400	348,900
Total deferred credits and other liabilities	482,600	401,600
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries		5,527,900
Noncontrolling interests in consolidated subsidiaries		157,500
Total equity	6,652,800	5,685,400
Total liabilities and equity	17,911,300	16,845,900
Consolidating Entries
Current assets
Cash and cash equivalents	0	0	$ 0	$ 0
Accounts receivable, net	0	0
Materials and supplies	0	0
Natural gas and natural gas liquids in storage	0	0
Other current assets	0	0
Total current assets	0	0
Property, plant and equipment
Property, plant and equipment	0	0
Accumulated depreciation and amortization	0	0
Net property, plant and equipment	0	0
Investments and other assets
Investments	(18,374,900)	(16,744,000)
Intercompany notes receivable	(14,269,900)	(15,257,800)
Other assets	(1,200)	(44,400)
Total investments and other assets	(32,646,000)	(32,046,200)
Total assets	(32,646,000)	(32,046,200)
Current liabilities
Current maturities of long-term debt	0	0
Short-term borrowings	0	0
Accounts payable	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Intercompany debt	(14,269,900)	(15,257,800)
Long-term debt, excluding current maturities	0	0
Deferred credits and other liabilities
Deferred income taxes	(1,200)	(44,400)
Other deferred credits	0	0
Total deferred credits and other liabilities	(1,200)	(44,400)
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries		(16,744,000)
Noncontrolling interests in consolidated subsidiaries		0
Total equity	(18,374,900)	(16,744,000)
Total liabilities and equity	$ (32,646,000)	$ (32,046,200)

SUPPLEMENTAL CONDENSED CONSOL_6

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Cash provided by operating activities			$ 1,516,450	$ 935,996
Investing activities
Capital expenditures	$ (694,303)	$ (135,199)	(1,309,655)	(330,431)
Cash paid for acquisition			(195,000)	0
Contributions to unconsolidated affiliates			(831)	(87,653)
Cash provided by (used in) investing activities			(1,484,820)	(394,597)
Financing activities
Dividends paid			(983,068)	(543,445)
Distributions to noncontrolling interests			(3,500)	(275,060)
Borrowing (repayment) of short-term borrowings, net			(494,673)	(178,027)
Issuance of long-term debt, net of discounts			1,245,773	1,190,067
Payments of Financing Costs			11,301	11,340
Repayment of long-term debt			(930,738)	(992,864)
Issuance of common stock			1,195,128	45,849
Other, net			(1,980)	(13,778)
Cash provided by (used in) financing activities			15,641	(778,598)
Change in cash and cash equivalents			47,271	(237,199)
Cash and cash equivalents at beginning of period			37,193	248,875
Cash and cash equivalents at end of period	84,464	11,676	84,464	11,676
Reportable Legal Entities | Parent Issuer & Guarantor
Operating activities
Cash provided by operating activities			964,400	620,800
Investing activities
Capital expenditures			(15,000)	(500)
Cash paid for acquisition			(195,000)
Contributions to unconsolidated affiliates			0	0
Other investing activities			0	0
Cash provided by (used in) investing activities			(210,000)	(500)
Financing activities
Dividends paid			(983,100)	(543,400)
Distributions to noncontrolling interests			0	0
Intercompany borrowings (advances), net			(1,640,500)	(2,376,900)
Borrowing (repayment) of short-term borrowings, net			(494,700)	932,300
Issuance of long-term debt, net of discounts			1,245,800	1,190,100
Repayment of long-term debt			0	(87,100)
Issuance of common stock			1,195,100	45,800
Other, net			(29,700)	(17,900)
Cash provided by (used in) financing activities			(707,100)	(857,100)
Change in cash and cash equivalents			47,300	(236,800)
Cash and cash equivalents at beginning of period			37,200	248,500
Cash and cash equivalents at end of period	84,500	11,700	84,500	11,700
Reportable Legal Entities | Subsidiary Issuer & Guarantor
Operating activities
Cash provided by operating activities			993,800	994,300
Investing activities
Capital expenditures			0	0
Cash paid for acquisition			0
Contributions to unconsolidated affiliates			0	0
Other investing activities			0	0
Cash provided by (used in) investing activities			0	0
Financing activities
Dividends paid			(999,000)	(999,000)
Distributions to noncontrolling interests			0	0
Intercompany borrowings (advances), net			930,200	2,022,200
Borrowing (repayment) of short-term borrowings, net			0	(1,110,300)
Issuance of long-term debt, net of discounts			0	0
Repayment of long-term debt			(925,000)	(900,000)
Issuance of common stock			0	0
Other, net			0	(7,200)
Cash provided by (used in) financing activities			(993,800)	(994,300)
Change in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of period			0	0
Cash and cash equivalents at end of period	0	0	0	0
Reportable Legal Entities | Guarantor Subsidiary
Operating activities
Cash provided by operating activities			48,900	42,100
Investing activities
Capital expenditures			0	0
Cash paid for acquisition			0
Contributions to unconsolidated affiliates			(500)	(83,000)
Other investing activities			10,800	11,200
Cash provided by (used in) investing activities			10,300	(71,800)
Financing activities
Dividends paid			(999,000)	(999,000)
Distributions to noncontrolling interests			0	0
Intercompany borrowings (advances), net			939,800	1,028,300
Borrowing (repayment) of short-term borrowings, net			0	0
Issuance of long-term debt, net of discounts			0	0
Repayment of long-term debt			0	0
Issuance of common stock			0	0
Other, net			0	0
Cash provided by (used in) financing activities			(59,200)	29,300
Change in cash and cash equivalents			0	(400)
Cash and cash equivalents at beginning of period			0	400
Cash and cash equivalents at end of period	0	0	0	0
Reportable Legal Entities | Combined Non-Guarantor Subsidiaries
Operating activities
Cash provided by operating activities			1,507,400	1,005,800
Investing activities
Capital expenditures			(1,294,700)	(329,900)
Cash paid for acquisition			0
Contributions to unconsolidated affiliates			(300)	(4,700)
Other investing activities			9,900	12,300
Cash provided by (used in) investing activities			(1,285,100)	(322,300)
Financing activities
Dividends paid			0	0
Distributions to noncontrolling interests			(3,500)	(4,100)
Intercompany borrowings (advances), net			(229,500)	(673,600)
Borrowing (repayment) of short-term borrowings, net			0	0
Issuance of long-term debt, net of discounts			0	0
Repayment of long-term debt			(5,700)	(5,800)
Issuance of common stock			0	0
Other, net			16,400	0
Cash provided by (used in) financing activities			(222,300)	(683,500)
Change in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of period			0	0
Cash and cash equivalents at end of period	0	0	0	0
Reportable Legal Entities | Total
Operating activities
Cash provided by operating activities			1,516,500	936,000
Investing activities
Capital expenditures			(1,309,700)	(330,400)
Cash paid for acquisition			(195,000)
Contributions to unconsolidated affiliates			(800)	(87,700)
Other investing activities			20,700	23,500
Cash provided by (used in) investing activities			(1,484,800)	(394,600)
Financing activities
Dividends paid			(983,100)	(543,400)
Distributions to noncontrolling interests			(3,500)	(275,100)
Intercompany borrowings (advances), net			0	0
Borrowing (repayment) of short-term borrowings, net			(494,700)	(178,000)
Issuance of long-term debt, net of discounts			1,245,800	1,190,100
Repayment of long-term debt			(930,700)	(992,900)
Issuance of common stock			1,195,100	45,800
Other, net			(13,300)	(25,100)
Cash provided by (used in) financing activities			15,600	(778,600)
Change in cash and cash equivalents			47,300	(237,200)
Cash and cash equivalents at beginning of period			37,200	248,900
Cash and cash equivalents at end of period	84,500	11,700	84,500	11,700
Consolidating Entries
Operating activities
Cash provided by operating activities			(1,998,000)	(1,727,000)
Investing activities
Capital expenditures			0	0
Cash paid for acquisition			0
Contributions to unconsolidated affiliates			0	0
Other investing activities			0	0
Cash provided by (used in) investing activities			0	0
Financing activities
Dividends paid			1,998,000	1,998,000
Distributions to noncontrolling interests			0	(271,000)
Intercompany borrowings (advances), net			0	0
Borrowing (repayment) of short-term borrowings, net			0	0
Issuance of long-term debt, net of discounts			0	0
Repayment of long-term debt			0	0
Issuance of common stock			0	0
Other, net			0	0
Cash provided by (used in) financing activities			1,998,000	1,727,000
Change in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of period			0	0
Cash and cash equivalents at end of period	$ 0	$ 0	$ 0	$ 0