ONEOK (OKE) 10-Q28 Apr 212021 Q1 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2021	Apr. 19, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-13643
Entity Registrant Name	ONEOK, Inc.
Entity Incorporation, State or Country Code	OK
Entity Tax Identification Number	73-1520922
Entity Address, Address Line One	100 West Fifth Street,
Entity Address, City or Town	Tulsa,
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	74103
City Area Code	918
Local Phone Number	588-7000
Title of 12(b) Security	Common stock, par value of $0.01
Trading Symbol	OKE
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		445,536,572
Entity Central Index Key	0001039684
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues
Revenues	$ 3,194,679	$ 2,136,672
Cost of sales and fuel (exclusive of items shown separately below)	2,121,510	1,276,928
Operations and maintenance	207,158	175,096
Depreciation and amortization	157,120	132,353
Impairment charges	0	604,024
General taxes	44,439	31,944
Gain on sale of assets	(269)	(204)
Operating income (loss)	664,721	(83,469)
Equity in net earnings from investments (Note I)	33,320	44,627
Impairment of equity investments	0	(37,730)
Allowance for equity funds used during construction	812	15,409
Other income	215	16,475
Other expense	(5,237)	(11,948)
Interest expense (net of capitalized interest of $5,095 and $30,875, respectively)	(185,523)	(140,616)
Income (loss) before income taxes	508,308	(197,252)
Income tax (expense) benefit	(122,132)	55,395
Net income (loss)	386,176	(141,857)
Less: Preferred stock dividends	275	275
Net income (loss) available to common shareholders	$ 385,901	$ (142,132)
Basic EPS (Note G)	$ 0.87	$ (0.34)
Diluted EPS (Note G)	$ 0.86	$ (0.34)
Average shares (thousands)
Basic	445,894	414,282
Diluted	446,885	414,282
Commodity Sales
Revenues
Revenues	$ 2,836,109	$ 1,808,620
Services
Revenues
Revenues	$ 358,570	$ 328,052

CONSOLIDATED STATEMENT OF INCOM

CONSOLIDATED STATEMENT OF INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest expense (net of capitalized interest)	$ 5,095	$ 30,875

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net income (loss)	$ 386,176	$ (141,857)
Other comprehensive income (loss), net of tax
Change in fair value of derivatives, net of tax of $(9,857) and $31,705, respectively	32,998	(106,141)
Derivative amounts reclassified to net income (loss), net of tax of $(12,361) and $4,518, respectively	41,387	(15,164)
Change in retirement and other postretirement benefit plan obligations, net of tax of $(1,087) and $(1,064), respectively	3,638	3,562
Other comprehensive income (loss) of unconsolidated affiliates, net of tax of $(2,339) and $2,283, respectively	7,830	(7,643)
Total other comprehensive income (loss), net of tax	85,853	(125,386)
Comprehensive income (loss)	$ 472,029	$ (267,243)

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (PARANTHETICAL) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Change in fair value of derivatives, tax	$ (9,857)	$ 31,705
Derivative amounts reclassified to net income, tax	(12,361)	4,518
Change in retirement and other postretirement benefit plan obligations, tax	(1,087)	(1,064)
Other comprehensive income (loss) of unconsolidated affiliates, tax	$ (2,339)	$ 2,283

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 402,413	$ 524,496
Accounts receivable, net	909,972	829,796
Materials and supplies	143,583	143,178
NGLs and natural gas in storage	369,604	227,810
Commodity imbalances	16,798	11,959
Other current assets	155,224	132,536
Total current assets	1,997,594	1,869,775
Property, plant and equipment
Property, plant and equipment	23,192,548	23,072,935
Accumulated depreciation and amortization	4,067,297	3,918,007
Net property, plant and equipment	19,125,251	19,154,928
Investments and other assets
Investments in unconsolidated affiliates	807,721	805,032
Goodwill and intangible assets	771,116	773,723
Other assets	478,247	475,296
Total investments and other assets	2,057,084	2,054,051
Total assets	23,179,929	23,078,754
Current liabilities
Current maturities of long-term debt (Note D)	543,757	7,650
Accounts payable	929,771	719,302
Commodity imbalances	209,626	186,372
Accrued taxes	65,862	89,428
Accrued interest	140,281	245,153
Operating lease liability, current	13,408	13,610
Other current liabilities	145,249	83,032
Total current liabilities	2,047,954	1,344,547
Long-term debt, excluding current maturities (Note D)	13,638,767	14,228,421
Deferred credits and other liabilities
Deferred income taxes	814,528	669,697
Operating lease liability, noncurrent	85,295	87,610
Other deferred credits	496,420	706,081
Total deferred credits and other liabilities	1,396,243	1,463,388
Commitments and contingencies (Note J)
Equity (Note E)
Preferred stock, $0.01 par value: authorized and issued 20,000 shares at March 31, 2021, and December 31, 2020	0	0
Common Stock, $0.01 par value: authorized 1,200,000,000 shares; issued 474,916,234 shares and outstanding 445,534,180 shares at March 31, 2021; issued 474,916,234 shares and outstanding 444,872,383 shares at December 31, 2020	4,749	4,749
Paid-in capital	7,305,274	7,353,396
Accumulated other comprehensive loss (Note F)	(465,596)	(551,449)
Retained earnings	0	0
Treasury stock, at cost: 29,382,054 shares at March 31, 2021, and 30,043,851 shares at December 31, 2020	(747,462)	(764,298)
Total equity	6,096,965	6,042,398
Total liabilities and equity	$ 23,179,929	$ 23,078,754

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Equity (Note E)
Preferred stock, shares, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares, issued (in shares)	20,000	20,000
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)	474,916,234	474,916,234
Common stock, shares, outstanding (in shares)	445,534,180	444,872,383
Treasury stock, shares, (in shares)	29,382,054	30,043,851

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities
Net income (loss)	$ 386,176	$ (141,857)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	157,120	132,353
Impairment charges	0	641,754
Equity in net earnings from investments	(33,320)	(44,627)
Distributions received from unconsolidated affiliates	30,862	41,577
Deferred income tax expense (benefit)	119,194	(55,949)
Other, net	11,672	(30,380)
Changes in assets and liabilities:
Accounts receivable	(85,212)	334,370
NGLs and natural gas in storage	(141,794)	173,885
Accounts payable	251,344	(350,701)
Commodity imbalances	18,415	(37,919)
Accrued interest	(104,872)	(68,918)
Risk-management assets and liabilities	(19,302)	(78,856)
Other assets and liabilities	(56,966)	(92,011)
Cash provided by operating activities	533,317	422,721
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	(176,734)	(949,679)
Distributions received from unconsolidated affiliates in excess of cumulative earnings	10,191	6,949
Other, net	(4,148)	(22,062)
Cash used in investing activities	(170,691)	(964,792)
Financing activities
Dividends paid	(416,229)	(386,667)
Repayment of short-term borrowings, net	0	(220,000)
Issuance of long-term debt, net of discounts	0	1,748,221
Debt financing costs	0	(15,444)
Repayment of long-term debt	(56,492)	(52,389)
Other, net	(11,988)	(20,978)
Cash provided by (used in) financing activities	(484,709)	1,052,743
Change in cash and cash equivalents	(122,083)	510,672
Cash and cash equivalents at beginning of period	524,496	20,958
Cash and cash equivalents at end of period	$ 402,413	$ 531,630

CONSOLIDATED STATEMENT OF CHANG

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings (Accumulated Deficit)	Treasury Stock
Shares, issued, beginning balance at Dec. 31, 2019		20,000	445,016,234
Total equity, beginning balance at Dec. 31, 2019	$ 6,225,951	$ 0	$ 4,450	$ 7,403,895	$ (374,000)	$ 0	$ (808,394)
Net income (loss)	(141,857)	0	0	0	0	(141,857)	0
Other comprehensive income (loss)	$ (125,386)	0	0	0	(125,386)	0	0
Preferred stock, dividends paid (in dollars per share)	$ 13.75
Preferred stock dividends	$ (275)	$ 0	0	(275)	0	0	0
Common Stock Issued During Period, Shares, Other		0
Common Stock Issued During Period, Value, Other	$ 7,089	$ 0	0	(9,286)	0	0	16,375
Common stock dividends paid (in dollars per share)	$ 0.935
Common Stock Dividends	$ (386,931)	0	0	(386,931)	0	0	0
Other, net	(17,950)	$ 0	$ 0	(17,950)	0	0	0
Shares, issued, ending balance at Mar. 31, 2020		20,000	445,016,234
Total equity, ending balance at Mar. 31, 2020	5,560,641	$ 0	$ 4,450	6,989,453	(499,386)	(141,857)	(792,019)
Shares, issued, beginning balance at Dec. 31, 2020		20,000	474,916,234
Total equity, beginning balance at Dec. 31, 2020	6,042,398	$ 0	$ 4,749	7,353,396	(551,449)	0	(764,298)
Net income (loss)	386,176	0	0	0	0	386,176	0
Other comprehensive income (loss)	$ 85,853	0	0	0	85,853	0	0
Preferred stock, dividends paid (in dollars per share)	$ 13.75
Preferred stock dividends	$ (275)	$ 0	0	0	0	(275)	0
Common Stock Issued During Period, Shares, Other		0
Common Stock Issued During Period, Value, Other	$ 6,677	$ 0	0	(10,159)	0	0	16,836
Common stock dividends paid (in dollars per share)	$ 0.935
Common Stock Dividends	$ (416,135)	0	0	(30,234)	0	(385,901)	0
Other, net	(7,729)	$ 0	$ 0	(7,729)	0	0	0
Shares, issued, ending balance at Mar. 31, 2021		20,000	474,916,234
Total equity, ending balance at Mar. 31, 2021	$ 6,096,965	$ 0	$ 4,749	$ 7,305,274	$ (465,596)	$ 0	$ (747,462)

CONSOLIDATED STATEMENT OF CHA_2

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY CONSOLIDATED STATEMENT OF CHANGES IN EQUITY Parenthetical - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Preferred stock, dividends paid (in dollars per share)	$ 13.75	$ 13.75
Common stock dividends paid (in dollars per share)	$ 0.935	$ 0.935

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Notes)	3 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Notes)	Mar. 31, 2021
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 2020 year-end Consolidated Balance Sheet data was derived from our audited Consolidated Financial Statements but does not include all disclosures required by GAAP. Certain reclassifications have been made in the prior year Consolidated 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. 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 discussed below or in our Annual Report were assessed and determined to be either not applicable or clarifications of ASUs previously issued. Except as discussed below or in our Annual Report, there have been no new accounting pronouncements that have become effective or have been issued that are of significance or potential significance to us.

FAIR VALUE MEASUREMENTS (Notes)

FAIR VALUE MEASUREMENTS (Notes)	3 Months Ended
FAIR VALUE MEASUREMENTS (Notes)	Mar. 31, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Determining Fair Value - For our fair value measurements, we utilize market prices, third-party pricing services, present value methods and standard option valuation models to determine the price we would receive from the sale of an asset or the transfer of a liability in an orderly transaction at the measurement date. 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. Many of the contracts in our derivative portfolio are executed in liquid markets where price transparency exists. Our financial commodity derivatives are generally settled through a NYMEX or ICE clearing broker account with daily margin requirements. We validate our valuation inputs with third-party information and settlement prices from other sources, where available. 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 the implied forward LIBOR yield curve. The fair value of our forward-starting interest-rate swaps is determined using financial models that incorporate the implied forward LIBOR yield curve for the same period as the future interest-rate swap settlements. We consider current market data in evaluating counterparties’, as well as our own, nonperformance risk, net of collateral, by using counterparty-specific bond yields. 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. 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. 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, including quoted prices for similar assets and liabilities in active markets and inputs from third-party pricing services supported with corroborative evidence. These balances are composed of over-the-counter interest-rate derivatives. • Level 3 - fair value measurements are based on inputs that may include one or more unobservable inputs, including internally developed commodity price curves that incorporate market data from broker quotes and third-party pricing services. These balances are composed predominantly of exchange-cleared and over-the-counter derivatives to hedge NGL price risk and natural gas basis risk between various transaction locations and the NYMEX Henry Hub. Our commodity derivatives are generally valued using forward quotes provided by third-party pricing services that are validated with other market data. We believe any measurement uncertainty at March 31, 2021, is immaterial as our Level 3 fair value measurements are based on unadjusted pricing information from broker quotes and third-party pricing services. We do not believe that our Level 3 fair value estimates have a material impact on our results of operations, as our derivatives are primarily accounted for as hedges. Determining the appropriate classification of our fair value measurements 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: March 31, 2021 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 6,380 $ — $ 113,776 $ 120,156 $ (120,156) $ — Interest-rate contracts — 241 — 241 — 241 Total derivative assets $ 6,380 $ 241 $ 113,776 $ 120,397 $ (120,156) $ 241 Derivative liabilities Commodity contracts Financial contracts $ (18,986) $ — $ (155,570) $ (174,556) $ 174,556 $ — Interest-rate contracts — (97,363) — (97,363) — (97,363) Total derivative liabilities $ (18,986) $ (97,363) $ (155,570) $ (271,919) $ 174,556 $ (97,363) (a) - Derivative assets and liabilities are presented in our Consolidated Balance Sheet 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 March 31, 2021, we held no cash and posted $108.0 million of cash with various counterparties, including $54.4 million of cash collateral that is offsetting derivative net liability positions under master-netting arrangements in the table above. The remaining $53.6 million of cash collateral in excess of derivative net liability positions is included in other current assets in our Consolidated Balance Sheet. December 31, 2020 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 6,697 $ — $ 103,801 $ 110,498 $ (110,498) $ — Total derivative assets $ 6,697 $ — $ 103,801 $ 110,498 $ (110,498) $ — Derivative liabilities Commodity contracts Financial contracts $ (10,489) $ — $ (135,122) $ (145,611) $ 145,611 $ — Interest-rate contracts — (203,407) — (203,407) — (203,407) Total derivative liabilities $ (10,489) $ (203,407) $ (135,122) $ (349,018) $ 145,611 $ (203,407) (a) - Derivative assets and liabilities are presented in our Consolidated Balance Sheet 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, 2020, we held no cash and posted $63.1 million of cash with various counterparties, including $35.1 million of cash collateral that is offsetting derivative net liability positions under master-netting arrangements in the table above. The remaining $28.0 million of cash collateral in excess of derivative net liability positions is included in other current assets in our Consolidated Balance Sheet. The following table sets forth a reconciliation of our Level 3 fair value measurements for the periods indicated: Three Months Ended March 31, Derivative Assets (Liabilities) 2021 2020 ( Thousands of dollars ) Net assets (liabilities) at beginning of period $ (31,321) $ 30,772 Total changes in fair value: Settlements included in net income (loss) (a) 24,738 (16,146) New Level 3 derivatives included in other comprehensive income (loss) (b) (4,612) 20,993 Unrealized change included in other comprehensive income (loss) (b) (30,599) 21,782 Net assets (liabilities) at end of period $ (41,794) $ 57,401 (a) - Included in commodity sales revenues/cost of sales and fuel in our Consolidated Statements of Income. (b) - Included in change in fair value of derivatives in our Consolidated Statements of Comprehensive Income. During the three months ended March 31, 2021 and 2020, there were no transfers in or out of Level 3 of the fair value hierarchy. 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 $15.8 billion and $16.3 billion at March 31, 2021, and December 31, 2020, respectively. The book value of our consolidated long-term debt, including current maturities, was $14.2 billion at March 31, 2021, and December 31, 2020. The estimated fair value of the aggregate long-term debt 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)	3 Months Ended
	Mar. 31, 2021
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 may 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 fee with POP contracts. Under certain fee with POP contracts, our fees and POP percentage may increase or decrease if production volumes, delivery pressures or commodity prices change relative to specified thresholds. In certain commodity price environments, our contractual fees on these fee with POP contracts may decrease, which impacts the average fee rate in our Natural Gas Gathering and Processing segment. 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 activities. 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 primarily exposed to commodity price risk on our intrastate pipelines because they consume natural gas in operations and retain natural gas from our customers for operations or as part of our fee for services provided. When the amount consumed in operations differs from the amount provided by our customers, our pipelines must buy or sell natural gas, or store or use natural gas 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 natural gas price fluctuations. At March 31, 2021, and December 31, 2020, 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 and interest-rate swaps. Interest-rate swaps are agreements to exchange interest payments at some future point based on specified notional amounts. At March 31, 2021, and December 31, 2020, we had forward-starting interest-rate swaps with notional amounts totaling $1.1 billion to hedge the variability of interest payments on a portion of our forecasted debt issuances. 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. 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: March 31, 2021 December 31, 2020 Location in our Assets (Liabilities) Assets (Liabilities) Derivatives designated as hedging instruments ( Thousands of dollars ) Commodity contracts (a) Financial contracts (b) $ 113,909 $ (168,369) $ 107,461 $ (142,573) Interest-rate contracts Other current assets/ liabilities 241 (65,329) — — Other deferred credits — (32,034) — (203,407) Total derivatives designated as hedging instruments 114,150 (265,732) 107,461 (345,980) Derivatives not designated as hedging instruments Commodity contracts (a) Financial contracts (b) 6,247 (6,187) 3,037 (3,038) Total derivatives not designated as hedging instruments 6,247 (6,187) 3,037 (3,038) Total derivatives $ 120,397 $ (271,919) $ 110,498 $ (349,018) (a) - Derivative assets and liabilities are presented in our Consolidated Balance Sheets on a net basis when a legally enforceable master-netting arrangement exists between the counterparty to a derivative contract and us. (b) - At March 31, 2021, and December 31, 2020, our derivative net liability positions under master-netting arrangements for financial contracts were fully offset by cash collateral of $54.4 million and $35.1 million, respectively. Notional Quantities for Derivative Instruments - The following table sets forth the notional quantities for derivative instruments held for the periods indicated: March 31, 2021 December 31, 2020 Contract Net Purchased/Payor Derivatives designated as hedging instruments: (a) Cash flow hedges Fixed price - Natural gas ( Bcf ) Futures (80.9) (43.3) - Crude oil and NGLs ( MMBbl ) Futures (10.9) (4.6) Basis - Natural gas ( Bcf ) Futures (80.9) (43.3) Interest-rate contracts ( Billions of dollars ) Swaps $ 1.1 $ 1.1 (a) - Notional amounts for derivatives not designated as hedging instruments are excluded from the table above due to fully offsetting notional quantities of 0.5 MMBbl and 0.8 MMBbl for NGLs fixed priced derivative instruments at March 31, 2021, and December 31, 2020, respectively. Cash Flow Hedges - The following table sets forth the unrealized change in fair value of cash flow hedges in other comprehensive income (loss) for the periods indicated: Three Months Ended March 31, 2021 2020 ( Thousands of dollars ) Commodity contracts $ (63,430) $ 87,195 Interest-rate contracts 106,285 (225,041) Total unrealized change in fair value of cash flow hedges in other comprehensive income (loss) $ 42,855 $ (137,846) The following table sets forth the effect of cash flow hedges on net income (loss) for the periods indicated: Location of Gain (Loss) Reclassified from Three Months Ended March 31, 2021 2020 ( Thousands of dollars ) Commodity contracts Commodity sales revenues $ (130,518) $ 44,999 Cost of sales and fuel 86,436 (15,039) Interest-rate contracts Interest expense (9,666) (10,278) Total change in fair value of cash flow hedges reclassified from accumulated other comprehensive loss into net income (loss) on derivatives $ (53,748) $ 19,682 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. Our financial commodity derivatives are generally settled through a NYMEX or ICE clearing broker account with daily margin requirements. However, we may enter into financial derivative instruments that contain provisions that require us to maintain an investment-grade credit rating from S&P, Fitch 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 March 31, 2021. 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 March 31, 2021, the credit exposure from our derivative assets is with investment-grade companies in the financial services sector.

DEBT DEBT (Notes)

DEBT DEBT (Notes)	3 Months Ended
DEBT DEBT (Notes)	Mar. 31, 2021
Debt Disclosure [Abstract]
Debt [Text Block]	DEBT The following table sets forth our consolidated debt for the periods indicated: March 31, December 31, ( Thousands of dollars ) Commercial paper outstanding $ — $ — Senior unsecured obligations: $700,000 at 4.25% due February 2022 536,107 541,877 $900,000 at 3.375% due October 2022 895,814 895,814 $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 2.75% due September 2024 500,000 500,000 $500,000 at 4.9% due March 2025 500,000 500,000 $400,000 at 2.2% due September 2025 387,000 387,000 $600,000 at 5.85% due January 2026 600,000 600,000 $500,000 at 4.0% due July 2027 500,000 500,000 $800,000 at 4.55% due July 2028 800,000 800,000 $100,000 at 6.875% due September 2028 100,000 100,000 $700,000 at 4.35% due March 2029 700,000 700,000 $750,000 at 3.4% due September 2029 714,251 714,251 $850,000 at 3.1% due March 2030 780,093 780,093 $600,000 at 6.35% due January 2031 600,000 600,000 $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 689,006 689,006 $1,000,000 at 5.2% due July 2048 1,000,000 1,000,000 $750,000 at 4.45% due September 2049 672,530 713,676 $500,000 at 4.5% due March 2050 443,015 451,270 $300,000 at 7.15% due January 2051 300,000 300,000 Guardian Pipeline Weighted average 7.85% due December 2022 11,745 13,657 Total debt 14,304,561 14,361,644 Unamortized portion of terminated swaps 12,884 13,314 Unamortized debt issuance costs and discounts (134,921) (138,887) Current maturities of long-term debt (543,757) (7,650) Long-term debt $ 13,638,767 $ 14,228,421 $2.5 Billion Credit Agreement - Our $2.5 Billion Credit Agreement is a 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). In 2020, we acquired additional interest in one of our equity investments and a related asset for $27 million, which allowed us to elect an acquisition adjustment period under our $2.5 Billion Credit Agreement and, as a result, increased our leverage ratio covenant to 5.5 to 1 for the fourth quarter 2020 and the two following quarters. Thereafter, the covenant will decrease to 5.0 to 1. At March 31, 2021, we had no outstanding borrowings, our ratio of indebtedness to adjusted EBITDA was 4.6 to 1, and we were in compliance with all covenants under our $2.5 Billion Credit Agreement. Debt Repurchases - During the three months ended March 31, 2021, we repurchased in the open market outstanding principal of certain of our senior notes in the amount of $55.2 million for an aggregate repurchase price of $54.6 million with cash on hand. Debt Guarantees - We, ONEOK Partners and the Intermediate Partnership have cross guarantees in place for our and ONEOK Partners’ indebtedness.

EQUITY (Notes)

EQUITY (Notes)	3 Months Ended
EQUITY (Notes)	Mar. 31, 2021
Equity [Abstract]
EQUITY	EQUITY 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 Series E Preferred Stock. Dividends paid on our common stock in February 2021 were $0.935 per share. A dividend of $0.935 per share was declared for shareholders of record at the close of business on April 26, 2021, payable May 14, 2021. Our 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% per year. We paid dividends for the Series E Preferred Stock of $0.3 million in February 2021. Dividends totaling $0.3 million were declared for the Series E Preferred Stock and are payable May 14, 2021.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Notes)	3 Months Ended
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Notes)	Mar. 31, 2021
ACCUMULATED OTHER COMPREHENSIVE LOSS	ACCUMULATED OTHER COMPREHENSIVE LOSS The following table sets forth the balance in accumulated other comprehensive loss for the period indicated: Risk- Retirement and Risk- Accumulated ( Thousands of dollars ) January 1, 2021 $ (377,446) $ (157,635) $ (16,368) $ (551,449) Other comprehensive income (loss) before reclassifications 32,998 (167) 7,372 40,203 Amounts reclassified to net income (c) 41,387 3,805 458 45,650 Other comprehensive income 74,385 3,638 7,830 85,853 March 31, 2021 $ (303,061) $ (153,997) $ (8,538) $ (465,596) (a) - All amounts are presented net of tax. (b) - Includes amounts related to supplemental executive retirement plan. (c) - See Note C for details of amounts reclassified to net income for risk-management assets/liabilities and Note H for retirement and other postretirement benefit plan obligations. The following table sets forth information about the balance of accumulated other comprehensive loss at March 31, 2021, representing unrealized gains (losses) related to risk-management assets and liabilities: Risk- ( Thousands of dollars ) Commodity derivative instruments expected to be realized within the next 33 months (b) $ (42,201) Settled interest-rate swaps to be recognized over the life of the long-term, fixed-rate debt (c) (186,076) Interest-rate swaps with future settlement dates expected to be amortized over the life of long-term debt (74,784) Accumulated other comprehensive loss at March 31, 2021 $ (303,061) (a) - All amounts are presented net of tax. (b) - Based on commodity prices on March 31, 2021, we expect $47.7 million in net losses, net of tax, over the next 12 months and $5.5 million in net gains, net of tax, thereafter. (c) - We expect net losses of $30.5 million, net of tax, will be reclassified into earnings during the next 12 months.

EARNINGS PER SHARE EARNINGS PER

EARNINGS PER SHARE EARNINGS PER SHARE (Notes)	3 Months Ended
EARNINGS PER SHARE EARNINGS PER SHARE (Notes)	Mar. 31, 2021
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 March 31, 2021 Income Shares Per Share ( Thousands, except per share amounts ) Basic EPS Net income available for common stock $ 385,901 445,894 $ 0.87 Diluted EPS Effect of dilutive securities — 991 Net income available for common stock and common stock equivalents $ 385,901 446,885 $ 0.86 Three Months Ended March 31, 2020 Loss Shares Per Share ( Thousands, except per share amounts ) Basic EPS Net loss available for common stock $ (142,132) 414,282 $ (0.34) Diluted EPS Effect of dilutive securities — — Net loss available for common stock and common stock equivalents (a) $ (142,132) 414,282 $ (0.34) (a) - For the three months ended March 31, 2020, 1,065,880 weighted-average shares have been excluded from the calculation of diluted loss per share as their inclusion would have been anti-dilutive due to our net loss available for common stock.

EMPLOYEE BENEFIT PLANS EMPLOYEE

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Notes)	3 Months Ended
EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Notes)	Mar. 31, 2021
Defined Benefit Plan [Abstract]
EMPLOYEE BENEFIT PLANS	EMPLOYEE BENEFIT PLANS The following table sets forth the components of net periodic benefit cost for our retirement and other postretirement benefit plans for the periods indicated: Retirement Benefits Other Postretirement Benefits Three Months Ended Three Months Ended March 31, March 31, 2021 2020 2021 2020 ( Thousands of dollars ) Components of net periodic benefit cost (income) Service cost $ 2,076 $ 2,036 $ 115 $ 115 Interest cost 4,220 4,574 442 442 Expected return on plan assets (6,269) (6,232) (722) (722) Amortization of prior service cost (a) 28 28 — — Amortization of net loss (a) 4,913 4,571 1 1 Net periodic benefit cost (income) $ 4,968 $ 4,977 $ (164) $ (164) (a) - These components of net periodic benefit cost (income) are recognized in accumulated other comprehensive loss and are reclassified to other expense in our Consolidated Statements of Income, with related income tax benefits of $1.1 million reclassified to income tax (expense) benefit for both the three months ended March 31, 2021 and 2020.

UNCONSOLIDATED AFFILIATES (Note

UNCONSOLIDATED AFFILIATES (Notes)	3 Months Ended
UNCONSOLIDATED AFFILIATES (Notes)	Mar. 31, 2021
Equity Method Investments and Joint Ventures [Abstract]
UNCONSOLIDATED AFFILIATES	UNCONSOLIDATED AFFILIATES Equity in Net Earnings from Investments and Impairments - The following table sets forth our equity in net earnings from investments for the periods indicated: Three Months Ended March 31, 2021 2020 ( Thousands of dollars ) Northern Border Pipeline $ 20,239 $ 22,120 Overland Pass Pipeline 2,972 14,111 Roadrunner 7,749 6,433 Other 2,360 1,963 Equity in net earnings from investments $ 33,320 $ 44,627 Impairment of equity investments $ — $ (37,730) Equity in net earnings from Overland Pass Pipeline decreased for the three months ended March 31, 2021, compared with the same period in 2020, due primarily to lower volumes. For the three months ended March 31, 2020, we incurred a noncash impairment charge of $30.5 million related to our 10.2% investment in Venice Energy Services Company in our Natural Gas Gathering and Processing segment, which includes $22.3 million related to equity-method goodwill, and a $7.2 million noncash impairment charge related to our 50% investment in Chisholm Pipeline Company in our Natural Gas Liquids segment. We incurred expenses in transactions with unconsolidated affiliates of $15.6 million and $45.3 million for the three months ended March 31, 2021 and 2020, respectively, primarily related to Northern Border Pipeline and Overland Pass Pipeline. Accounts payable to our equity-method investees at March 31, 2021, and December 31, 2020, were $5.2 million and $8.4 million, respectively. We have an operating agreement with Roadrunner that provides for reimbursement or payment to us for management services and certain operating costs, which are included in operating income (loss) in our Consolidated Statements of Income.

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Notes)	3 Months Ended
COMMITMENTS AND CONTINGENCIES (Notes)	Mar. 31, 2021
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, fractionation, 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 laws and regulations that relate to air and water quality, hazardous and solid waste management and disposal, cultural resource protection and other environmental and safety matters. The cost of planning, designing, constructing and operating pipelines, plants and other facilities must incorporate compliance with these laws, 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 does not believe that, based on currently known information, a material risk of noncompliance with these laws and regulations exists that will affect adversely our consolidated results of operations, financial condition or cash flows. Legal Proceedings - We are a party to various 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)	3 Months Ended
REVENUE REVENUE (Notes)	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	REVENUES Accounting Policies - Many of the contract types described within Note A of the Notes to Consolidated Financial Statement in our Annual Report contain additional fees or charges payable by customers for nonperformance (e.g., minimum volume commitments or product specifications), which are considered to be variable consideration. These fees and charges are not recorded until it is probable that a significant reversal of the associated revenue will not occur. Contract Assets and Contract Liabilities - Our contract asset balances at the beginning and end of the period primarily relate to our firm service transportation contracts with tiered rates, which are not material. The following table sets forth the balances in contract liabilities for the periods indicated: Contract Liabilities ( Millions of dollars ) Balance at December 31, 2020 (a) $ 41.4 Revenue recognized included in beginning balance (20.4) Net additions 12.3 Balance at March 31, 2021 (b) $ 33.3 (a) - Contract liabilities of $23.7 million and $17.7 million are included in other current liabilities and other deferred credits, respectively, in our Consolidated Balance Sheet. (b) - Contract liabilities of $15.9 million and $17.4 million are included in other current liabilities and other deferred credits, respectively, in our Consolidated Balance Sheet. Receivables from Customers and Revenue Disaggregation - Substantially all of the balances in accounts receivable on our Consolidated Balance Sheets at March 31, 2021, and December 31, 2020, relate to customer receivables. Revenues sources are disaggregated in Note L. Transaction Price Allocated to Unsatisfied Performance Obligations - 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. The following table presents aggregate value allocated to unsatisfied performance obligations as of March 31, 2021, 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 23 years: Expected Period of Recognition in Revenue ( Millions of dollars ) Remainder of 2021 $ 247.6 2022 273.4 2023 244.3 2024 204.1 2025 and beyond 796.1 Total estimated transaction price allocated to unsatisfied performance obligations $ 1,765.5 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. 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)	3 Months Ended
SEGMENTS (Notes)	Mar. 31, 2021
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 transports and stores natural gas via regulated intrastate and interstate 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. 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 $ 491,807 $ 2,414,830 $ — $ 2,906,637 Residue natural gas sales 312,247 — 115,455 427,702 Gathering, processing and exchange services revenue 31,687 113,231 — 144,918 Transportation and storage revenue — 48,728 132,947 181,675 Other 4,000 33,276 412 37,688 Total revenues (c) 839,741 2,610,065 248,814 3,698,620 Cost of sales and fuel (exclusive of depreciation and operating costs) (555,306) (2,060,319) (10,013) (2,625,638) Operating costs (84,598) (124,369) (42,317) (251,284) Equity in net earnings from investments 1,728 3,604 27,988 33,320 Noncash compensation expense and other 3,151 6,647 1,703 11,501 Segment adjusted EBITDA $ 204,716 $ 435,628 $ 226,175 $ 866,519 Depreciation and amortization $ (67,032) $ (74,542) $ (14,476) $ (156,050) Investments in unconsolidated affiliates $ 24,584 $ 420,614 $ 362,523 $ 807,721 Total assets $ 6,535,260 $ 13,944,887 $ 2,096,459 $ 22,576,606 Capital expenditures $ 39,651 $ 112,021 $ 21,157 $ 172,829 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $570.6 million, of which $516.1 million related to revenues within the segment, and cost of sales and fuel of $135.8 million. (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $181.4 million and cost of sales and fuel of $12.8 million. (c) - Intersegment revenues are primarily commodity sales which are based on the contracted selling price that is generally index-based and settled monthly, and for the Natural Gas Gathering and Processing segment totaled $481.6 million. Intersegment revenues for the Natural Gas Liquids and Natural Gas Pipelines segments were not material. Three Months Ended Total Other and Total ( Thousands of dollars ) Reconciliations of total segments to consolidated NGL and condensate sales $ 2,906,637 $ (500,064) $ 2,406,573 Residue natural gas sales 427,702 — 427,702 Gathering, processing and exchange services revenue 144,918 — 144,918 Transportation and storage revenue 181,675 (3,535) 178,140 Other 37,688 (342) 37,346 Total revenues (a) $ 3,698,620 $ (503,941) $ 3,194,679 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (2,625,638) $ 504,128 $ (2,121,510) Operating costs $ (251,284) $ (313) $ (251,597) Depreciation and amortization $ (156,050) $ (1,070) $ (157,120) Equity in net earnings from investments $ 33,320 $ — $ 33,320 Investments in unconsolidated affiliates $ 807,721 $ — $ 807,721 Total assets $ 22,576,606 $ 603,323 $ 23,179,929 Capital expenditures $ 172,829 $ 3,905 $ 176,734 (a) - Noncustomer revenue for the three months ended March 31, 2021, totaled $(132.2) million related primarily to losses from derivatives on commodity contracts. Three Months Ended Natural Gas Natural Gas Natural Gas Total ( Thousands of dollars ) NGL and condensate sales $ 219,917 $ 1,596,711 $ — $ 1,816,628 Residue natural gas sales 189,051 — 2,035 191,086 Gathering, processing and exchange services revenue 37,937 120,536 — 158,473 Transportation and storage revenue — 50,755 118,364 169,119 Other 3,075 2,590 384 6,049 Total revenues (c) 449,980 1,770,592 120,783 2,341,355 Cost of sales and fuel (exclusive of depreciation and operating costs) (202,170) (1,278,754) (1,539) (1,482,463) Operating costs (84,470) (89,571) (33,307) (207,348) Equity in net earnings from investments 806 15,268 28,553 44,627 Noncash compensation expense and other (4,498) (6,619) (1,966) (13,083) Segment adjusted EBITDA $ 159,648 $ 410,916 $ 112,524 $ 683,088 Depreciation and amortization $ (58,756) $ (57,841) $ (14,769) $ (131,366) Impairment charges (d) $ (564,353) $ (77,401) $ — $ (641,754) Investments in unconsolidated affiliates $ 4,276 $ 435,024 $ 371,179 $ 810,479 Total assets $ 6,374,552 $ 12,682,807 $ 2,089,362 $ 21,146,721 Capital expenditures $ 181,610 $ 746,183 $ 16,590 $ 944,383 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $435.1 million, of which $378.2 million related to revenues within the segment, and cost of sales and fuel of $120.4 million. (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $73.9 million and cost of sales and fuel of $6.1 million. (c) - Intersegment revenues are primarily commodity sales, which are based on the contracted selling price that is generally index-based and settled monthly, and for the Natural Gas Gathering and Processing segment totaled $213.3 million. Intersegment revenues for the Natural Gas Liquids and Natural Gas Pipelines segments were not material. (d) - Includes noncash impairment charges of $380.5 million related primarily to long-lived assets, $153.4 million related to goodwill and $30.5 million related to an investment in an unconsolidated affiliate in our Natural Gas Gathering and Processing segment; and $70.2 million related to long-lived assets and $7.2 million related to an investment in an unconsolidated affiliate in our Natural Gas Liquids segment. Three Months Ended Total Other and Total ( Thousands of dollars ) Reconciliations of total segments to consolidated NGL and condensate sales $ 1,816,628 $ (199,472) $ 1,617,156 Residue natural gas sales 191,086 (1,032) 190,054 Gathering, processing and exchange services revenue 158,473 — 158,473 Transportation and storage revenue 169,119 (3,809) 165,310 Other 6,049 (370) 5,679 Total revenues (a) $ 2,341,355 $ (204,683) $ 2,136,672 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (1,482,463) $ 205,535 $ (1,276,928) Operating costs $ (207,348) $ 308 $ (207,040) Depreciation and amortization $ (131,366) $ (987) $ (132,353) Impairment charges $ (641,754) $ — $ (641,754) Equity in net earnings from investments $ 44,627 $ — $ 44,627 Investments in unconsolidated affiliates $ 810,479 $ — $ 810,479 Total assets $ 21,146,721 $ 822,719 $ 21,969,440 Capital expenditures $ 944,383 $ 5,296 $ 949,679 (a) - Noncustomer revenue for the three months ended March 31, 2020, totaled $80.2 million related primarily to gains from derivatives on commodity contracts. Three Months Ended March 31, 2021 2020 ( Thousands of dollars ) Reconciliation of net income (loss) to total segment adjusted EBITDA Net income (loss) $ 386,176 $ (141,857) Add: Interest expense, net of capitalized interest 185,523 140,616 Depreciation and amortization 157,120 132,353 Income tax expense (benefit) 122,132 (55,395) Impairment charges — 641,754 Noncash compensation expense 16,283 (1,302) Other corporate costs and equity AFUDC (a) (715) (33,081) Total segment adjusted EBITDA $ 866,519 $ 683,088 (a) - The three months ended March 31, 2020, includes corporate gains of $15.8 million on extinguishment of debt related to open market repurchases.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Mar. 31, 2021
Accounting Policies [Abstract]
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 2020 year-end Consolidated Balance Sheet data was derived from our audited Consolidated Financial Statements but does not include all disclosures required by GAAP. Certain reclassifications have been made in the prior year Consolidated 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 discussed below or in our Annual Report were assessed and determined to be either not applicable or clarifications of ASUs previously issued. Except as discussed below or in our Annual Report, there have been no new accounting pronouncements that have become effective or have been issued that are of significance or potential significance to us.

FAIR VALUE MEASUREMENTS FAIR VA

FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS (Policies)	3 Months Ended
FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS (Policies)	Mar. 31, 2021
Fair Value Accounting Policy [Abstract]
Fair Value of Financial Instruments, Policy [Policy Text Block]	Determining Fair Value - For our fair value measurements, we utilize market prices, third-party pricing services, present value methods and standard option valuation models to determine the price we would receive from the sale of an asset or the transfer of a liability in an orderly transaction at the measurement date. 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. Many of the contracts in our derivative portfolio are executed in liquid markets where price transparency exists. Our financial commodity derivatives are generally settled through a NYMEX or ICE clearing broker account with daily margin requirements. We validate our valuation inputs with third-party information and settlement prices from other sources, where available. 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 the implied forward LIBOR yield curve. The fair value of our forward-starting interest-rate swaps is determined using financial models that incorporate the implied forward LIBOR yield curve for the same period as the future interest-rate swap settlements. We consider current market data in evaluating counterparties’, as well as our own, nonperformance risk, net of collateral, by using counterparty-specific bond yields. 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. 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. 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, including quoted prices for similar assets and liabilities in active markets and inputs from third-party pricing services supported with corroborative evidence. These balances are composed of over-the-counter interest-rate derivatives. • Level 3 - fair value measurements are based on inputs that may include one or more unobservable inputs, including internally developed commodity price curves that incorporate market data from broker quotes and third-party pricing services. These balances are composed predominantly of exchange-cleared and over-the-counter derivatives to hedge NGL price risk and natural gas basis risk between various transaction locations and the NYMEX Henry Hub. Our commodity derivatives are generally valued using forward quotes provided by third-party pricing services that are validated with other market data. We believe any measurement uncertainty at March 31, 2021, is immaterial as our Level 3 fair value measurements are based on unadjusted pricing information from broker quotes and third-party pricing services. We do not believe that our Level 3 fair value estimates have a material impact on our results of operations, as our derivatives are primarily accounted for as hedges. Determining the appropriate classification of our fair value measurements 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.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities (Policies)	3 Months Ended
Derivative Instruments and Hedging Activities (Policies)	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives, Reporting of Derivative Activity	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.

REVENUE REVENUE (Policies)

REVENUE REVENUE (Policies)	3 Months Ended
REVENUE REVENUE (Policies)	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Policy Text Block]	Accounting Policies - Many of the contract types described within Note A of the Notes to Consolidated Financial Statement in our Annual Report contain additional fees or charges payable by customers for nonperformance (e.g., minimum volume commitments or product specifications), which are considered to be variable consideration. These fees and charges are not recorded until it is probable that a significant reversal of the associated revenue will not occur.

SEGMENTS SEGMENTS (Policies)

SEGMENTS SEGMENTS (Policies)	3 Months Ended
SEGMENTS SEGMENTS (Policies)	Mar. 31, 2021
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.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
FAIR VALUE MEASUREMENTS (Tables)	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Recurring Fair Value Measurements	The following tables set forth our recurring fair value measurements for the periods indicated: March 31, 2021 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 6,380 $ — $ 113,776 $ 120,156 $ (120,156) $ — Interest-rate contracts — 241 — 241 — 241 Total derivative assets $ 6,380 $ 241 $ 113,776 $ 120,397 $ (120,156) $ 241 Derivative liabilities Commodity contracts Financial contracts $ (18,986) $ — $ (155,570) $ (174,556) $ 174,556 $ — Interest-rate contracts — (97,363) — (97,363) — (97,363) Total derivative liabilities $ (18,986) $ (97,363) $ (155,570) $ (271,919) $ 174,556 $ (97,363) (a) - Derivative assets and liabilities are presented in our Consolidated Balance Sheet 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 March 31, 2021, we held no cash and posted $108.0 million of cash with various counterparties, including $54.4 million of cash collateral that is offsetting derivative net liability positions under master-netting arrangements in the table above. The remaining $53.6 million of cash collateral in excess of derivative net liability positions is included in other current assets in our Consolidated Balance Sheet. December 31, 2020 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 6,697 $ — $ 103,801 $ 110,498 $ (110,498) $ — Total derivative assets $ 6,697 $ — $ 103,801 $ 110,498 $ (110,498) $ — Derivative liabilities Commodity contracts Financial contracts $ (10,489) $ — $ (135,122) $ (145,611) $ 145,611 $ — Interest-rate contracts — (203,407) — (203,407) — (203,407) Total derivative liabilities $ (10,489) $ (203,407) $ (135,122) $ (349,018) $ 145,611 $ (203,407) (a) - Derivative assets and liabilities are presented in our Consolidated Balance Sheet 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, 2020, we held no cash and posted $63.1 million of cash with various counterparties, including $35.1 million of cash collateral that is offsetting derivative net liability positions under master-netting arrangements in the table above. The remaining $28.0 million of cash collateral in excess of derivative net liability positions is included in other current assets in our Consolidated Balance Sheet.
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 March 31, Derivative Assets (Liabilities) 2021 2020 ( Thousands of dollars ) Net assets (liabilities) at beginning of period $ (31,321) $ 30,772 Total changes in fair value: Settlements included in net income (loss) (a) 24,738 (16,146) New Level 3 derivatives included in other comprehensive income (loss) (b) (4,612) 20,993 Unrealized change included in other comprehensive income (loss) (b) (30,599) 21,782 Net assets (liabilities) at end of period $ (41,794) $ 57,401 (a) - Included in commodity sales revenues/cost of sales and fuel in our Consolidated Statements of Income.

RISK MANAGEMENT AND HEDGING A_2

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES (Tables)	3 Months Ended
	Mar. 31, 2021
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: March 31, 2021 December 31, 2020 Location in our Assets (Liabilities) Assets (Liabilities) Derivatives designated as hedging instruments ( Thousands of dollars ) Commodity contracts (a) Financial contracts (b) $ 113,909 $ (168,369) $ 107,461 $ (142,573) Interest-rate contracts Other current assets/ liabilities 241 (65,329) — — Other deferred credits — (32,034) — (203,407) Total derivatives designated as hedging instruments 114,150 (265,732) 107,461 (345,980) Derivatives not designated as hedging instruments Commodity contracts (a) Financial contracts (b) 6,247 (6,187) 3,037 (3,038) Total derivatives not designated as hedging instruments 6,247 (6,187) 3,037 (3,038) Total derivatives $ 120,397 $ (271,919) $ 110,498 $ (349,018) (a) - Derivative assets and liabilities are presented in our Consolidated Balance Sheets on a net basis when a legally enforceable master-netting arrangement exists between the counterparty to a derivative contract and us.
Notional Amounts of Derivative Instruments	The following table sets forth the notional quantities for derivative instruments held for the periods indicated: March 31, 2021 December 31, 2020 Contract Net Purchased/Payor Derivatives designated as hedging instruments: (a) Cash flow hedges Fixed price - Natural gas ( Bcf ) Futures (80.9) (43.3) - Crude oil and NGLs ( MMBbl ) Futures (10.9) (4.6) Basis - Natural gas ( Bcf ) Futures (80.9) (43.3) Interest-rate contracts ( Billions of dollars ) Swaps $ 1.1 $ 1.1 (a) - Notional amounts for derivatives not designated as hedging instruments are excluded from the table above due to fully offsetting notional quantities of 0.5 MMBbl and 0.8 MMBbl for NGLs fixed priced derivative instruments at March 31, 2021, and December 31, 2020, respectively.
Schedule of Cash Flow Hedging Instruments Effect on Comprehensive Income (Loss)	The following table sets forth the unrealized change in fair value of cash flow hedges in other comprehensive income (loss) for the periods indicated: Three Months Ended March 31, 2021 2020 ( Thousands of dollars ) Commodity contracts $ (63,430) $ 87,195 Interest-rate contracts 106,285 (225,041) Total unrealized change in fair value of cash flow hedges in other comprehensive income (loss) $ 42,855 $ (137,846)
Schedule of Cash Flow Hedging Instruments Effect on Income (Loss)	The following table sets forth the effect of cash flow hedges on net income (loss) for the periods indicated: Location of Gain (Loss) Reclassified from Three Months Ended March 31, 2021 2020 ( Thousands of dollars ) Commodity contracts Commodity sales revenues $ (130,518) $ 44,999 Cost of sales and fuel 86,436 (15,039) Interest-rate contracts Interest expense (9,666) (10,278) Total change in fair value of cash flow hedges reclassified from accumulated other comprehensive loss into net income (loss) on derivatives $ (53,748) $ 19,682

DEBT DEBT (Tables)

DEBT DEBT (Tables)	3 Months Ended
DEBT DEBT (Tables)	Mar. 31, 2021
Debt Instrument [Line Items]
Debt [Table Text Block]	The following table sets forth our consolidated debt for the periods indicated: March 31, December 31, ( Thousands of dollars ) Commercial paper outstanding $ — $ — Senior unsecured obligations: $700,000 at 4.25% due February 2022 536,107 541,877 $900,000 at 3.375% due October 2022 895,814 895,814 $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 2.75% due September 2024 500,000 500,000 $500,000 at 4.9% due March 2025 500,000 500,000 $400,000 at 2.2% due September 2025 387,000 387,000 $600,000 at 5.85% due January 2026 600,000 600,000 $500,000 at 4.0% due July 2027 500,000 500,000 $800,000 at 4.55% due July 2028 800,000 800,000 $100,000 at 6.875% due September 2028 100,000 100,000 $700,000 at 4.35% due March 2029 700,000 700,000 $750,000 at 3.4% due September 2029 714,251 714,251 $850,000 at 3.1% due March 2030 780,093 780,093 $600,000 at 6.35% due January 2031 600,000 600,000 $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 689,006 689,006 $1,000,000 at 5.2% due July 2048 1,000,000 1,000,000 $750,000 at 4.45% due September 2049 672,530 713,676 $500,000 at 4.5% due March 2050 443,015 451,270 $300,000 at 7.15% due January 2051 300,000 300,000 Guardian Pipeline Weighted average 7.85% due December 2022 11,745 13,657 Total debt 14,304,561 14,361,644 Unamortized portion of terminated swaps 12,884 13,314 Unamortized debt issuance costs and discounts (134,921) (138,887) Current maturities of long-term debt (543,757) (7,650) Long-term debt $ 13,638,767 $ 14,228,421

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	3 Months Ended
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	Mar. 31, 2021
Accumulated Other Comprehensive Loss	The following table sets forth the balance in accumulated other comprehensive loss for the period indicated: Risk- Retirement and Risk- Accumulated ( Thousands of dollars ) January 1, 2021 $ (377,446) $ (157,635) $ (16,368) $ (551,449) Other comprehensive income (loss) before reclassifications 32,998 (167) 7,372 40,203 Amounts reclassified to net income (c) 41,387 3,805 458 45,650 Other comprehensive income 74,385 3,638 7,830 85,853 March 31, 2021 $ (303,061) $ (153,997) $ (8,538) $ (465,596) (a) - All amounts are presented net of tax. (b) - Includes amounts related to supplemental executive retirement plan. (c) - See Note C for details of amounts reclassified to net income for risk-management assets/liabilities and Note H for retirement and other postretirement benefit plan obligations.
Schedule of Accumulated Other Comprehensive Loss for Risk-Management Assets/Liabilities [Table Text Block]	The following table sets forth information about the balance of accumulated other comprehensive loss at March 31, 2021, representing unrealized gains (losses) related to risk-management assets and liabilities: Risk- ( Thousands of dollars ) Commodity derivative instruments expected to be realized within the next 33 months (b) $ (42,201) Settled interest-rate swaps to be recognized over the life of the long-term, fixed-rate debt (c) (186,076) Interest-rate swaps with future settlement dates expected to be amortized over the life of long-term debt (74,784) Accumulated other comprehensive loss at March 31, 2021 $ (303,061) (a) - All amounts are presented net of tax. (b) - Based on commodity prices on March 31, 2021, we expect $47.7 million in net losses, net of tax, over the next 12 months and $5.5 million in net gains, net of tax, thereafter. (c) - We expect net losses of $30.5 million, net of tax, will be reclassified into earnings during the next 12 months.

EARNINGS PER SHARE EARNINGS P_2

EARNINGS PER SHARE EARNINGS PER SHARE (Tables)	3 Months Ended
EARNINGS PER SHARE EARNINGS PER SHARE (Tables)	Mar. 31, 2021
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 March 31, 2021 Income Shares Per Share ( Thousands, except per share amounts ) Basic EPS Net income available for common stock $ 385,901 445,894 $ 0.87 Diluted EPS Effect of dilutive securities — 991 Net income available for common stock and common stock equivalents $ 385,901 446,885 $ 0.86 Three Months Ended March 31, 2020 Loss Shares Per Share ( Thousands, except per share amounts ) Basic EPS Net loss available for common stock $ (142,132) 414,282 $ (0.34) Diluted EPS Effect of dilutive securities — — Net loss available for common stock and common stock equivalents (a) $ (142,132) 414,282 $ (0.34) (a) - For the three months ended March 31, 2020, 1,065,880 weighted-average shares have been excluded from the calculation of diluted loss per share as their inclusion would have been anti-dilutive due to our net loss available for common stock.

EMPLOYEE BENEFIT PLANS EMPLOY_2

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Tables)	3 Months Ended
EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Tables)	Mar. 31, 2021
Defined Benefit Plan [Abstract]
Components of net periodic benefit cost for retirement and other postretirement benefit plans	The following table sets forth the components of net periodic benefit cost for our retirement and other postretirement benefit plans for the periods indicated: Retirement Benefits Other Postretirement Benefits Three Months Ended Three Months Ended March 31, March 31, 2021 2020 2021 2020 ( Thousands of dollars ) Components of net periodic benefit cost (income) Service cost $ 2,076 $ 2,036 $ 115 $ 115 Interest cost 4,220 4,574 442 442 Expected return on plan assets (6,269) (6,232) (722) (722) Amortization of prior service cost (a) 28 28 — — Amortization of net loss (a) 4,913 4,571 1 1 Net periodic benefit cost (income) $ 4,968 $ 4,977 $ (164) $ (164) (a) - These components of net periodic benefit cost (income) are recognized in accumulated other comprehensive loss and are reclassified to other expense in our Consolidated Statements of Income, with related income tax benefits of $1.1 million reclassified to income tax (expense) benefit for both the three months ended March 31, 2021 and 2020.

UNCONSOLIDATED AFFILIATES (Tabl

UNCONSOLIDATED AFFILIATES (Tables)	3 Months Ended
UNCONSOLIDATED AFFILIATES (Tables)	Mar. 31, 2021
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 March 31, 2021 2020 ( Thousands of dollars ) Northern Border Pipeline $ 20,239 $ 22,120 Overland Pass Pipeline 2,972 14,111 Roadrunner 7,749 6,433 Other 2,360 1,963 Equity in net earnings from investments $ 33,320 $ 44,627 Impairment of equity investments $ — $ (37,730)

REVENUE REVENUE (Tables)

REVENUE REVENUE (Tables)	3 Months Ended
REVENUE REVENUE (Tables)	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Contract with Customer, Asset and Liability [Table Text Block]	The following table sets forth the balances in contract liabilities for the periods indicated: Contract Liabilities ( Millions of dollars ) Balance at December 31, 2020 (a) $ 41.4 Revenue recognized included in beginning balance (20.4) Net additions 12.3 Balance at March 31, 2021 (b) $ 33.3 (a) - Contract liabilities of $23.7 million and $17.7 million are included in other current liabilities and other deferred credits, respectively, in our Consolidated Balance Sheet. (b) - Contract liabilities of $15.9 million and $17.4 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 March 31, 2021, 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 23 years: Expected Period of Recognition in Revenue ( Millions of dollars ) Remainder of 2021 $ 247.6 2022 273.4 2023 244.3 2024 204.1 2025 and beyond 796.1 Total estimated transaction price allocated to unsatisfied performance obligations $ 1,765.5

SEGMENTS (Tables)

SEGMENTS (Tables)	3 Months Ended
SEGMENTS (Tables)	Mar. 31, 2021
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 $ 491,807 $ 2,414,830 $ — $ 2,906,637 Residue natural gas sales 312,247 — 115,455 427,702 Gathering, processing and exchange services revenue 31,687 113,231 — 144,918 Transportation and storage revenue — 48,728 132,947 181,675 Other 4,000 33,276 412 37,688 Total revenues (c) 839,741 2,610,065 248,814 3,698,620 Cost of sales and fuel (exclusive of depreciation and operating costs) (555,306) (2,060,319) (10,013) (2,625,638) Operating costs (84,598) (124,369) (42,317) (251,284) Equity in net earnings from investments 1,728 3,604 27,988 33,320 Noncash compensation expense and other 3,151 6,647 1,703 11,501 Segment adjusted EBITDA $ 204,716 $ 435,628 $ 226,175 $ 866,519 Depreciation and amortization $ (67,032) $ (74,542) $ (14,476) $ (156,050) Investments in unconsolidated affiliates $ 24,584 $ 420,614 $ 362,523 $ 807,721 Total assets $ 6,535,260 $ 13,944,887 $ 2,096,459 $ 22,576,606 Capital expenditures $ 39,651 $ 112,021 $ 21,157 $ 172,829 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $570.6 million, of which $516.1 million related to revenues within the segment, and cost of sales and fuel of $135.8 million. (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $181.4 million and cost of sales and fuel of $12.8 million. (c) - Intersegment revenues are primarily commodity sales which are based on the contracted selling price that is generally index-based and settled monthly, and for the Natural Gas Gathering and Processing segment totaled $481.6 million. Intersegment revenues for the Natural Gas Liquids and Natural Gas Pipelines segments were not material. Three Months Ended Total Other and Total ( Thousands of dollars ) Reconciliations of total segments to consolidated NGL and condensate sales $ 2,906,637 $ (500,064) $ 2,406,573 Residue natural gas sales 427,702 — 427,702 Gathering, processing and exchange services revenue 144,918 — 144,918 Transportation and storage revenue 181,675 (3,535) 178,140 Other 37,688 (342) 37,346 Total revenues (a) $ 3,698,620 $ (503,941) $ 3,194,679 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (2,625,638) $ 504,128 $ (2,121,510) Operating costs $ (251,284) $ (313) $ (251,597) Depreciation and amortization $ (156,050) $ (1,070) $ (157,120) Equity in net earnings from investments $ 33,320 $ — $ 33,320 Investments in unconsolidated affiliates $ 807,721 $ — $ 807,721 Total assets $ 22,576,606 $ 603,323 $ 23,179,929 Capital expenditures $ 172,829 $ 3,905 $ 176,734 (a) - Noncustomer revenue for the three months ended March 31, 2021, totaled $(132.2) million related primarily to losses from derivatives on commodity contracts. Three Months Ended Natural Gas Natural Gas Natural Gas Total ( Thousands of dollars ) NGL and condensate sales $ 219,917 $ 1,596,711 $ — $ 1,816,628 Residue natural gas sales 189,051 — 2,035 191,086 Gathering, processing and exchange services revenue 37,937 120,536 — 158,473 Transportation and storage revenue — 50,755 118,364 169,119 Other 3,075 2,590 384 6,049 Total revenues (c) 449,980 1,770,592 120,783 2,341,355 Cost of sales and fuel (exclusive of depreciation and operating costs) (202,170) (1,278,754) (1,539) (1,482,463) Operating costs (84,470) (89,571) (33,307) (207,348) Equity in net earnings from investments 806 15,268 28,553 44,627 Noncash compensation expense and other (4,498) (6,619) (1,966) (13,083) Segment adjusted EBITDA $ 159,648 $ 410,916 $ 112,524 $ 683,088 Depreciation and amortization $ (58,756) $ (57,841) $ (14,769) $ (131,366) Impairment charges (d) $ (564,353) $ (77,401) $ — $ (641,754) Investments in unconsolidated affiliates $ 4,276 $ 435,024 $ 371,179 $ 810,479 Total assets $ 6,374,552 $ 12,682,807 $ 2,089,362 $ 21,146,721 Capital expenditures $ 181,610 $ 746,183 $ 16,590 $ 944,383 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $435.1 million, of which $378.2 million related to revenues within the segment, and cost of sales and fuel of $120.4 million. (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $73.9 million and cost of sales and fuel of $6.1 million. (c) - Intersegment revenues are primarily commodity sales, which are based on the contracted selling price that is generally index-based and settled monthly, and for the Natural Gas Gathering and Processing segment totaled $213.3 million. Intersegment revenues for the Natural Gas Liquids and Natural Gas Pipelines segments were not material. (d) - Includes noncash impairment charges of $380.5 million related primarily to long-lived assets, $153.4 million related to goodwill and $30.5 million related to an investment in an unconsolidated affiliate in our Natural Gas Gathering and Processing segment; and $70.2 million related to long-lived assets and $7.2 million related to an investment in an unconsolidated affiliate in our Natural Gas Liquids segment. Three Months Ended Total Other and Total ( Thousands of dollars ) Reconciliations of total segments to consolidated NGL and condensate sales $ 1,816,628 $ (199,472) $ 1,617,156 Residue natural gas sales 191,086 (1,032) 190,054 Gathering, processing and exchange services revenue 158,473 — 158,473 Transportation and storage revenue 169,119 (3,809) 165,310 Other 6,049 (370) 5,679 Total revenues (a) $ 2,341,355 $ (204,683) $ 2,136,672 Cost of sales and fuel (exclusive of depreciation and operating costs) $ (1,482,463) $ 205,535 $ (1,276,928) Operating costs $ (207,348) $ 308 $ (207,040) Depreciation and amortization $ (131,366) $ (987) $ (132,353) Impairment charges $ (641,754) $ — $ (641,754) Equity in net earnings from investments $ 44,627 $ — $ 44,627 Investments in unconsolidated affiliates $ 810,479 $ — $ 810,479 Total assets $ 21,146,721 $ 822,719 $ 21,969,440 Capital expenditures $ 944,383 $ 5,296 $ 949,679 (a) - Noncustomer revenue for the three months ended March 31, 2020, totaled $80.2 million related primarily to gains from derivatives on commodity contracts. Three Months Ended March 31, 2021 2020 ( Thousands of dollars ) Reconciliation of net income (loss) to total segment adjusted EBITDA Net income (loss) $ 386,176 $ (141,857) Add: Interest expense, net of capitalized interest 185,523 140,616 Depreciation and amortization 157,120 132,353 Income tax expense (benefit) 122,132 (55,395) Impairment charges — 641,754 Noncash compensation expense 16,283 (1,302) Other corporate costs and equity AFUDC (a) (715) (33,081) Total segment adjusted EBITDA $ 866,519 $ 683,088 (a) - The three months ended March 31, 2020, includes corporate gains of $15.8 million on extinguishment of debt related to open market repurchases.

FAIR VALUE MEASUREMENTS - Part

FAIR VALUE MEASUREMENTS - Part 1 (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash held - offsetting derivative net asset positions under master-netting arrangements	$ 0	$ 0
Cash posted - total	108,000	63,100
Cash posted - offsetting derivative net liability positions under master-netting arrangements	54,400	35,100
Cash posted - remaining in excess of derivative net liability positions included in consolidated Balance Sheets	53,600	28,000
Long-term debt, fair value	15,800,000	16,300,000
Long-term debt	14,200,000	14,200,000
Fair Value, Recurring [Member] \| Gross Fair Value Measurement [Member]
Derivative assets
Derivative asset, fair value, gross	120,397	110,498
Derivative liabilities
Derivative liability, fair value, gross	(271,919)	(349,018)
Fair Value, Recurring [Member] \| Gross Fair Value Measurement [Member] \| Financial Contracts
Derivative assets
Derivative asset, fair value, gross	120,156	110,498
Derivative liabilities
Derivative liability, fair value, gross	(174,556)	(145,611)
Fair Value, Recurring [Member] \| Gross Fair Value Measurement [Member] \| Interest Rate Contracts
Derivative assets
Interest-rate contracts	241
Derivative liabilities
Interest-rate contracts	(97,363)	(203,407)
Fair Value, Recurring [Member]
Derivative assets
Derivative assets	241	0
Derivative assets netting	(120,156)	(110,498)
Derivative liabilities
Derivative liabilities	(97,363)	(203,407)
Derivative liabilities netting	174,556	145,611
Fair Value, Recurring [Member] \| Financial Contracts
Derivative assets
Derivative assets	0	0
Derivative assets netting	(120,156)	(110,498)
Derivative liabilities
Derivative liabilities	0	0
Derivative liabilities netting	174,556	145,611
Fair Value, Recurring [Member] \| Interest Rate Contracts
Derivative assets
Interest-rate contracts	241
Derivative assets netting	0
Derivative liabilities
Interest-rate contracts	(97,363)	(203,407)
Derivative liabilities netting	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Derivative assets
Derivative asset, fair value, gross	6,380	6,697
Derivative liabilities
Derivative liability, fair value, gross	(18,986)	(10,489)
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Financial Contracts
Derivative assets
Derivative asset, fair value, gross	6,380	6,697
Derivative liabilities
Derivative liability, fair value, gross	(18,986)	(10,489)
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Interest Rate Contracts
Derivative assets
Interest-rate contracts	0
Derivative liabilities
Interest-rate contracts	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Derivative assets
Derivative asset, fair value, gross	241	0
Derivative liabilities
Derivative liability, fair value, gross	(97,363)	(203,407)
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Financial Contracts
Derivative assets
Derivative asset, fair value, gross	0	0
Derivative liabilities
Derivative liability, fair value, gross	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Interest Rate Contracts
Derivative assets
Interest-rate contracts	241
Derivative liabilities
Interest-rate contracts	(97,363)	(203,407)
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Derivative assets
Derivative asset, fair value, gross	113,776	103,801
Derivative liabilities
Derivative liability, fair value, gross	(155,570)	(135,122)
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Financial Contracts
Derivative assets
Derivative asset, fair value, gross	113,776	103,801
Derivative liabilities
Derivative liability, fair value, gross	(155,570)	(135,122)
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Interest Rate Contracts
Derivative assets
Interest-rate contracts	0
Derivative liabilities
Interest-rate contracts	$ 0	$ 0

FAIR VALUE MEASUREMENTS - Par_2

FAIR VALUE MEASUREMENTS - Part 2 (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]
Net assets (liabilities) at beginning of period	$ (31,321)	$ 30,772
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements	24,738	(16,146)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, New Level 3 Derivatives	(4,612)	20,993
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Unrealized Change Included in other comprehensive income (loss)	(30,599)	21,782
Net assets (liabilities) at end of period	(41,794)	57,401
Transfers in or out of level 3	$ 0	$ 0

RISK MANAGEMENT AND HEDGING A_3

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES Part 1 (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Derivative, Fair Value [Line Items]
Assets	$ 120,397	$ 110,498
(Liabilities)	(271,919)	(349,018)
Derivative, Net Liability Position, Aggregate Fair Value	0
Cash posted - offsetting derivative net liability positions under master-netting arrangements	54,400	35,100
Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	114,150	107,461
(Liabilities)	(265,732)	(345,980)
Derivatives not designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	6,247	3,037
(Liabilities)	(6,187)	(3,038)
Natural Gas Pipelines
Derivative, Fair Value [Line Items]
Derivative, Fair Value, Net	0	0
Other Current Assets [Member] \| Interest Rate Contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	241	0
Other Current Liabilities [Member] \| Interest Rate Contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
(Liabilities)	(65,329)	0
Other Deferred Credits \| Interest Rate Contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	0	0
(Liabilities)	(32,034)	(203,407)
Fully Netted Assets/Liabilities \| Commodity Contracts \| Financial contracts \| Derivatives designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	113,909	107,461
(Liabilities)	(168,369)	(142,573)
Fully Netted Assets/Liabilities \| Commodity Contracts \| Financial contracts \| Derivatives not designated as hedging instruments
Derivative, Fair Value [Line Items]
Assets	6,247	3,037
(Liabilities)	$ (6,187)	$ (3,038)

RISK MANAGEMENT AND HEDGING A_4

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES, Part 2 (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021USD ($)BcfMMBbls	Dec. 31, 2020USD ($)MMBblsBcf
Derivative [Line Items]
Cash posted - offsetting derivative net liability positions under master-netting arrangements \| $	$ 54.4	$ 35.1
Derivatives designated as Hedging Instrument \| Futures \| - Natural gas (Bcf) \| Fixed price \| Net Purchasor, Sellor
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| Bcf	(80.9)	(43.3)
Derivatives designated as Hedging Instrument \| Futures \| - Natural gas (Bcf) \| Basis \| Net Purchasor, Sellor
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| Bcf	(80.9)	(43.3)
Derivatives designated as Hedging Instrument \| Futures \| - Crude oil and NGLs (MMBbl) \| Fixed price \| Net Purchasor, Sellor
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| MMBbls	(10.9)	(4.6)
Derivatives designated as Hedging Instrument \| Interest Rate Contracts \| Net Purchasor, Sellor
Derivative [Line Items]
Derivative, Notional Amount \| $	$ 1,100	$ 1,100
Derivatives not designated as hedging instruments \| Futures \| - Crude oil and NGLs (MMBbl) \| Fixed price \| Purchased/ Payor
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| MMBbls	0.5	0.8
Derivatives not designated as hedging instruments \| Futures \| - Crude oil and NGLs (MMBbl) \| Fixed price \| Sold/ Receiver
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| MMBbls	(0.5)	(0.8)
Forecasted Debt Issuances [Member] \| Cash Flow Hedging [Member] \| Forward contracts \| Interest Rate Contracts
Derivative [Line Items]
Derivative, Notional Amount \| $	$ 1,100	$ 1,100

RISK MANAGEMENT AND HEDGING A_5

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES Part 3 (Details) - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized change in fair value of cash flow hedges in other comprehensive income (loss)	$ 42,855	$ (137,846)
Change in fair value of cash flow hedges reclassified from accumulated other comprehensive loss into net income (loss) on derivatives	(53,748)	19,682
Commodity Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized change in fair value of cash flow hedges in other comprehensive income (loss)	(63,430)	87,195
Commodity Contracts \| Commodity sales revenues
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of cash flow hedges reclassified from accumulated other comprehensive loss into net income (loss) on derivatives	(130,518)	44,999
Commodity Contracts \| Cost of sales and fuel
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of cash flow hedges reclassified from accumulated other comprehensive loss into net income (loss) on derivatives	86,436	(15,039)
Interest Rate Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized change in fair value of cash flow hedges in other comprehensive income (loss)	106,285	(225,041)
Interest Rate Contracts \| Interest expense
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of cash flow hedges reclassified from accumulated other comprehensive loss into net income (loss) on derivatives	$ (9,666)	$ (10,278)

DEBT DEBT (Details)

DEBT DEBT (Details) $ in Thousands	3 Months Ended
DEBT DEBT (Details) $ in Thousands	Mar. 31, 2021USD ($)Rate	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Total debt	$ 14,304,561	$ 14,361,644
Unamortized portion of terminated swaps	12,884	13,314
Unamortized debt issuance costs and discounts	(134,921)	(138,887)
Current maturities of long-term debt	(543,757)	(7,650)
Long-term debt	13,638,767	14,228,421
Long-term Debt, Repurchased Face Amount	55,200
Repayments of Debt	54,600
Business Combination, Consideration Transferred		27,000
$2.5 Billion Credit Agreement [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	2,500,000
Line of Credit Facility, Amount Outstanding	$ 0
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). In 2020, we acquired additional interest in one of our equity investments and a related asset for $27 million, which allowed us to elect an acquisition adjustment period under our $2.5 Billion Credit Agreement and, as a result, increased our leverage ratio covenant to 5.5 to 1 for the fourth quarter 2020 and the two following quarters. Thereafter, the covenant will decrease to 5.0 to 1.
Indebtedness To Adjusted EBITDA From Acquisitions Maximum	5.5
Indebtedness To Adjusted EBITDA Maximum	5
Indebtedness To Adjusted EBITDA Current	4.6
Guardian Pipeline [Member] \| Notes Payables due 2022 [Member]
Debt Instrument [Line Items]
Total debt	$ 11,745	13,657
Average interest rate (in hundredths) \| Rate	7.85%
Subsidiary Issuer [Member] \| 3.375% Notes Payable due 2022 [Member]
Debt Instrument [Line Items]
Total debt	$ 895,814	895,814
Debt Instrument, Face Amount	$ 900,000
Interest Rate (in hundredths) \| Rate	3.375%
Subsidiary Issuer [Member] \| 5.0% Notes Payable due 2023 [Member]
Debt Instrument [Line Items]
Total debt	$ 425,000	425,000
Debt Instrument, Face Amount	$ 425,000
Interest Rate (in hundredths) \| Rate	5.00%
Subsidiary Issuer [Member] \| 4.9% Notes Payable due 2025 [Member]
Debt Instrument [Line Items]
Total debt	$ 500,000	500,000
Debt Instrument, Face Amount	$ 500,000
Interest Rate (in hundredths) \| Rate	4.90%
Subsidiary Issuer [Member] \| 6.65% Notes Payable due 2036 [Member]
Debt Instrument [Line Items]
Total debt	$ 600,000	600,000
Debt Instrument, Face Amount	$ 600,000
Interest Rate (in hundredths) \| Rate	6.65%
Subsidiary Issuer [Member] \| 6.85% Notes Payable due 2037 [Member]
Debt Instrument [Line Items]
Total debt	$ 600,000	600,000
Debt Instrument, Face Amount	$ 600,000
Interest Rate (in hundredths) \| Rate	6.85%
Subsidiary Issuer [Member] \| 6.125% Notes Payable due 2041 [Member]
Debt Instrument [Line Items]
Total debt	$ 650,000	650,000
Debt Instrument, Face Amount	$ 650,000
Interest Rate (in hundredths) \| Rate	6.125%
Subsidiary Issuer [Member] \| 6.2% Notes Payable due 2043 [Member]
Debt Instrument [Line Items]
Total debt	$ 400,000	400,000
Debt Instrument, Face Amount	$ 400,000
Interest Rate (in hundredths) \| Rate	6.20%
Parent Company
Debt Instrument [Line Items]
Commercial paper	$ 0	0
Parent Company \| 4.25% Notes Payable due 2022 [Member]
Debt Instrument [Line Items]
Total debt	536,107	541,877
Debt Instrument, Face Amount	$ 700,000
Interest Rate (in hundredths) \| Rate	4.25%
Parent Company \| 7.5% Notes Payable due 2023 [Member]
Debt Instrument [Line Items]
Total debt	$ 500,000	500,000
Debt Instrument, Face Amount	$ 500,000
Interest Rate (in hundredths) \| Rate	7.50%
Parent Company \| 2.75% Notes Payable due 2024 [Member]
Debt Instrument [Line Items]
Total debt	$ 500,000	500,000
Debt Instrument, Face Amount	$ 500,000
Interest Rate (in hundredths) \| Rate	2.75%
Parent Company \| 2.2% Notes Payable due 2025 [Member]
Debt Instrument [Line Items]
Total debt	$ 387,000	387,000
Debt Instrument, Face Amount	$ 400,000
Interest Rate (in hundredths) \| Rate	2.20%
Parent Company \| 5.85% Notes Payable due 2026 [Member]
Debt Instrument [Line Items]
Total debt	$ 600,000	600,000
Debt Instrument, Face Amount	$ 600,000
Interest Rate (in hundredths) \| Rate	5.85%
Parent Company \| 4.0% Notes Payable due 2027 [Member]
Debt Instrument [Line Items]
Total debt	$ 500,000	500,000
Debt Instrument, Face Amount	$ 500,000
Interest Rate (in hundredths) \| Rate	4.00%
Parent Company \| 4.55% Notes Payable due 2028 [Member]
Debt Instrument [Line Items]
Total debt	$ 800,000	800,000
Debt Instrument, Face Amount	$ 800,000
Interest Rate (in hundredths) \| Rate	4.55%
Parent Company \| 6.875% Notes Payable due 2028 [Member]
Debt Instrument [Line Items]
Total debt	$ 100,000	100,000
Debt Instrument, Face Amount	$ 100,000
Interest Rate (in hundredths) \| Rate	6.875%
Parent Company \| 4.35% Notes Payable due 2029 [Member]
Debt Instrument [Line Items]
Total debt	$ 700,000	700,000
Debt Instrument, Face Amount	$ 700,000
Interest Rate (in hundredths) \| Rate	4.35%
Parent Company \| 3.4% Notes Payable due 2029 [Member]
Debt Instrument [Line Items]
Total debt	$ 714,251	714,251
Debt Instrument, Face Amount	$ 750,000
Interest Rate (in hundredths) \| Rate	3.40%
Parent Company \| 3.1% Notes Payable due 2030 [Member]
Debt Instrument [Line Items]
Total debt	$ 780,093	780,093
Debt Instrument, Face Amount	$ 850,000
Interest Rate (in hundredths) \| Rate	3.10%
Parent Company \| 6.35% Notes Payable due 2031 [Member]
Debt Instrument [Line Items]
Total debt	$ 600,000	600,000
Debt Instrument, Face Amount	$ 600,000
Interest Rate (in hundredths) \| Rate	6.35%
Parent Company \| 6.0% Notes Payable due 2035 [Member]
Debt Instrument [Line Items]
Total debt	$ 400,000	400,000
Debt Instrument, Face Amount	$ 400,000
Interest Rate (in hundredths) \| Rate	6.00%
Parent Company \| 4.95% Notes Payable due 2047 [Member]
Debt Instrument [Line Items]
Total debt	$ 689,006	689,006
Debt Instrument, Face Amount	$ 700,000
Interest Rate (in hundredths) \| Rate	4.95%
Parent Company \| 5.2% Notes Payable due 2048 [Member]
Debt Instrument [Line Items]
Total debt	$ 1,000,000	1,000,000
Debt Instrument, Face Amount	$ 1,000,000
Interest Rate (in hundredths) \| Rate	5.20%
Parent Company \| 4.45% Notes Payable due 2049 [Member]
Debt Instrument [Line Items]
Total debt	$ 672,530	713,676
Debt Instrument, Face Amount	$ 750,000
Interest Rate (in hundredths) \| Rate	4.45%
Parent Company \| 4.5% Notes Payable due 2050 [Member]
Debt Instrument [Line Items]
Total debt	$ 443,015	451,270
Debt Instrument, Face Amount	$ 500,000
Interest Rate (in hundredths) \| Rate	4.50%
Parent Company \| 7.15% Notes Payable due 2051 [Member]
Debt Instrument [Line Items]
Total debt	$ 300,000	$ 300,000
Debt Instrument, Face Amount	$ 300,000
Interest Rate (in hundredths) \| Rate	7.15%

EQUITY (Details)

EQUITY (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Mar. 31, 2020
Dividends, Per Share, Cash Paid		$ 0.935	$ 0.935
Dividends, Preferred Stock, Cash		$ 300
Preferred Stock, Dividends, Declared		$ 275	$ 275
Series E Preferred Stock [Member]
Preferred Stock, Dividend Rate, Percentage		5.50%
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared	$ 0.935	$ 0.935
Dividends Payable, Date of Record	Apr. 26, 2021
Dividends Payable, Date to be Paid	May 14, 2021
Preferred Stock, Dividends, Declared	$ 300

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Risk management assets/liabilities - January 1	$ (377,446)
Retirement and other postretirement benefit plan obligations - January 1	(157,635)
Risk-management assets/liabilities of unconsolidated affiliates - January 1	(16,368)
Accumulated other comprehensive loss - January 1	(551,449)
Other comprehensive income (loss) before reclassification, risk-management assets/liabilities	32,998	$ (106,141)
Other comprehensive (income) loss before reclassification, retirement and postretirement benefit plan obligations	(167)
Other comprehensive income (loss) before reclassification, risk-management assets/liabilities of unconsolidated affiliates	7,372
Other comprehensive income (loss) before reclassifications	40,203
Other comprehensive income reclassification adjustment from AOCI for risk-management assets/liabilities, net of tax	41,387	(15,164)
Other comprehensive income, retirement and other postretirement benefit plans, reclassification adjustment from AOCI, net of tax	3,805
Other comprehensive income, reclassification adjustment from AOCI for other comprehensive income attributable to unconsolidated affiliates, net of tax	458
Other comprehensive income, reclassification adjustment included in net income, net of tax	45,650
Other comprehensive income (loss), risk-management assets/liabilities, after reclassification adjustment, net of tax	74,385
Other comprehensive (income) loss, retirement and other postretirement benefit plans, after reclassification adjustment, net of tax	3,638	$ 3,562
Other comprehensive income (loss), risk-management assets/liabilities of unconsolidated affiliates, net of tax	7,830
Other comprehensive income (loss), net of tax	85,853
Risk management assets/liabilities - March 31	(303,061)
Retirement and other postretirement benefit plan obligations - March 31	(153,997)
Risk-management assets/liabilities of unconsolidated affiliates - March 31	(8,538)
Accumulated other comprehensive loss - March 31	(465,596)
Cash Flow Hedging [Member] \| Commodity Contracts
Unrealized gain loss on cash flow hedges net of tax accumulated other comprehensive income (loss)	(42,201)
Price risk cash flow hedge unrealized gain (loss) to be reclassified during next 12 months	(47,700)
Commodity cash flow hedge gain (loss) to be reclassified after next 12 months net	5,500
Cash Flow Hedging [Member] \| Interest Rate Contracts
Amount of accumulated other comprehensive income (loss) attributable primarily to settled interest-rate swaps.	(186,076)
Amount of accumulated other comprehensive income (loss) attributable primarily to forward starting interest-rate swaps.	(74,784)
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net	$ (30,500)

EARNINGS PER SHARE EARNINGS P_3

EARNINGS PER SHARE EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Basic EPS
Net income (loss) available for common stock	$ 385,901	$ (142,132)
Shares	445,894,000	414,282,000
Earnings (loss) per share, basic	$ 0.87	$ (0.34)
Diluted EPS
Effect of dilutive securities	$ 0	$ 0
Effect of dilutive securities, number of shares	991,000	0
Net income (loss) available for common stock and common stock equivalents	$ 385,901	$ (142,132)
Shares	446,885,000	414,282,000
Earnings (loss) per share, diluted	$ 0.86	$ (0.34)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		1,065,880

EMPLOYEE BENEFIT PLANS EMPLOY_3

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income tax benefits reclassified from accumulated other comprehensive loss to income tax (expense) benefit
Income tax benefit	$ 1,100	$ 1,100
Retirement Benefits
Components of net periodic benefit cost (income)
Service cost	2,076	2,036
Interest cost	4,220	4,574
Expected return on plan assets	(6,269)	(6,232)
Amortization of prior service cost	28	28
Amortization of net loss	4,913	4,571
Net periodic benefit cost (income)	4,968	4,977
Other Postretirement Benefits Plan
Components of net periodic benefit cost (income)
Service cost	115	115
Interest cost	442	442
Expected return on plan assets	(722)	(722)
Amortization of prior service cost	0	0
Amortization of net loss	1	1
Net periodic benefit cost (income)	$ (164)	$ (164)

UNCONSOLIDATED AFFILIATES (Deta

UNCONSOLIDATED AFFILIATES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Equity in net earnings from investments	$ 33,320	$ 44,627
Accounts Payable, Related Parties, Current	5,200		$ 8,400
Impairment of equity investments	0	(37,730)
Natural Gas Gathering And Processing [Member]
Schedule of Equity Method Investments [Line Items]
Equity in net earnings from investments	1,728	806
Natural Gas Liquids
Schedule of Equity Method Investments [Line Items]
Equity in net earnings from investments	3,604	15,268
Unconsolidated Affiliates [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Expenses from Transactions with Related Parties	15,600	45,300
Northern Border Pipeline
Schedule of Equity Method Investments [Line Items]
Equity in net earnings from investments	20,239	22,120
Overland Pass Pipeline
Schedule of Equity Method Investments [Line Items]
Equity in net earnings from investments	2,972	14,111
Roadrunner
Schedule of Equity Method Investments [Line Items]
Equity in net earnings from investments	7,749	6,433
Other Unconsolidated Affiliates
Schedule of Equity Method Investments [Line Items]
Equity in net earnings from investments	$ 2,360	1,963
Venice Energy Services Company [Member] \| Natural Gas Gathering And Processing [Member]
Schedule of Equity Method Investments [Line Items]
Impairment of equity investments		$ (30,500)
Equity Method Investment, Ownership Percentage		10.20%
Impairment of equity investments - goodwill		$ (22,300)
Chisholm Pipeline Company [Member] \| Natural Gas Liquids
Schedule of Equity Method Investments [Line Items]
Impairment of equity investments		$ (7,200)
Equity Method Investment, Ownership Percentage		50.00%

REVENUE REVENUE (Details)

REVENUE REVENUE (Details) - USD ($) $ in Millions	3 Months Ended
REVENUE REVENUE (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Contract with Customer, Liability [Abstract]
Contract with customer, liability	$ 33.3	$ 41.4
Revenue recognized included in beginning balance	(20.4)
Net additions	12.3
Contract with Customer, Liability, Current	15.9	23.7
Contract with Customer, Liability, Noncurrent	17.4	$ 17.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 1,765.5
Remaining Contract Terms [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Performance Obligation, Contract Term	one month to 23 years
2021 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 247.6
2022 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	273.4
2023 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	244.3
2024 [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	204.1
Thereafter [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 796.1

SEGMENTS (Details)

SEGMENTS (Details) - USD ($) $ in Thousands	3 Months Ended
SEGMENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Segment disclosure [Abstract]
Revenues	$ 3,194,679	$ 2,136,672
Cost of sales and fuel (exclusive of depreciation and operating costs)	(2,121,510)	(1,276,928)
Operating costs	(251,597)	(207,040)
Equity in net earnings from investments	33,320	44,627
Depreciation and amortization	(157,120)	(132,353)
Impairment charges	0	(641,754)
Investments in unconsolidated affiliates	807,721	810,479	$ 805,032
Total assets	23,179,929	21,969,440	$ 23,078,754
Capital expenditures	176,734	949,679
Net income (loss)	386,176	(141,857)
Interest expense, net of capitalized interest	185,523	140,616
Income tax expense (benefit)	122,132	(55,395)
Noncash compensation expense	16,283	(1,302)
Other corporate costs and noncash items	(715)	(33,081)
Gain (loss) on extinguishment of debt		15,800
Impairment of equity investments	0	37,730
Natural Gas Gathering And Processing [Member]
Segment disclosure [Abstract]
Impairment of long-lived assets		380,500
Goodwill impairment charge		153,400
Natural Gas Liquids
Segment disclosure [Abstract]
Impairment of long-lived assets		70,200
Natural Gas Gathering And Processing [Member]
Segment disclosure [Abstract]
Revenues	839,741	449,980
Cost of sales and fuel (exclusive of depreciation and operating costs)	(555,306)	(202,170)
Operating costs	(84,598)	(84,470)
Equity in net earnings from investments	1,728	806
Noncash compensation expense and other	3,151	(4,498)
Segment adjusted EBITDA	204,716	159,648
Depreciation and amortization	(67,032)	(58,756)
Impairment charges		(564,353)
Investments in unconsolidated affiliates	24,584	4,276
Total assets	6,535,260	6,374,552
Capital expenditures	39,651	181,610
Natural Gas Gathering And Processing [Member] \| Venice Energy Services Company [Member]
Segment disclosure [Abstract]
Impairment of equity investments		30,500
Natural Gas Liquids
Segment disclosure [Abstract]
Revenues	2,610,065	1,770,592
Cost of sales and fuel (exclusive of depreciation and operating costs)	(2,060,319)	(1,278,754)
Operating costs	(124,369)	(89,571)
Equity in net earnings from investments	3,604	15,268
Noncash compensation expense and other	6,647	(6,619)
Segment adjusted EBITDA	435,628	410,916
Depreciation and amortization	(74,542)	(57,841)
Impairment charges		(77,401)
Investments in unconsolidated affiliates	420,614	435,024
Total assets	13,944,887	12,682,807
Capital expenditures	112,021	746,183
Natural Gas Liquids \| Chisholm Pipeline Company [Member]
Segment disclosure [Abstract]
Impairment of equity investments		7,200
Natural Gas Pipelines
Segment disclosure [Abstract]
Revenues	248,814	120,783
Cost of sales and fuel (exclusive of depreciation and operating costs)	(10,013)	(1,539)
Operating costs	(42,317)	(33,307)
Equity in net earnings from investments	27,988	28,553
Noncash compensation expense and other	1,703	(1,966)
Segment adjusted EBITDA	226,175	112,524
Depreciation and amortization	(14,476)	(14,769)
Impairment charges		0
Investments in unconsolidated affiliates	362,523	371,179
Total assets	2,096,459	2,089,362
Capital expenditures	21,157	16,590
Total Segments [Member]
Segment disclosure [Abstract]
Revenues	3,698,620	2,341,355
Cost of sales and fuel (exclusive of depreciation and operating costs)	(2,625,638)	(1,482,463)
Operating costs	(251,284)	(207,348)
Equity in net earnings from investments	33,320	44,627
Noncash compensation expense and other	11,501	(13,083)
Segment adjusted EBITDA	866,519	683,088
Depreciation and amortization	(156,050)	(131,366)
Impairment charges		(641,754)
Investments in unconsolidated affiliates	807,721	810,479
Total assets	22,576,606	21,146,721
Capital expenditures	172,829	944,383
Other and Eliminations
Segment disclosure [Abstract]
Revenues	(503,941)	(204,683)
Cost of sales and fuel (exclusive of depreciation and operating costs)	504,128	205,535
Operating costs	(313)	308
Equity in net earnings from investments	0	0
Depreciation and amortization	(1,070)	(987)
Impairment charges		0
Investments in unconsolidated affiliates	0	0
Total assets	603,323	822,719
Capital expenditures	3,905	5,296
Natural Gas Gathering and Processing Intersegment [Member] \| Natural Gas Gathering And Processing [Member]
Segment disclosure [Abstract]
Revenues	481,600	213,300
Natural Gas Liquids Regulated [Member] \| Natural Gas Liquids
Segment disclosure [Abstract]
Revenues	570,600	435,100
Cost of sales and fuel (exclusive of depreciation and operating costs)	(135,800)	(120,400)
Natural Gas Pipelines Regulated [Member] \| Natural Gas Pipelines
Segment disclosure [Abstract]
Revenues	181,400	73,900
Cost of sales and fuel (exclusive of depreciation and operating costs)	(12,800)	(6,100)
Operating Segments [Member] \| Natural Gas Liquids Regulated [Member] \| Natural Gas Liquids
Segment disclosure [Abstract]
Revenues	516,100	378,200
Noncustomer [Domain]
Segment disclosure [Abstract]
Revenues	(132,200)	80,200
NGL and Condensate Sales [Member]
Segment disclosure [Abstract]
Revenues	2,406,573	1,617,156
NGL and Condensate Sales [Member] \| Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	491,807	219,917
NGL and Condensate Sales [Member] \| Natural Gas Liquids
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,414,830	1,596,711
NGL and Condensate Sales [Member] \| Natural Gas Pipelines
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	2,906,637	1,816,628
NGL and Condensate Sales [Member] \| Other and Eliminations
Segment disclosure [Abstract]
Revenues	(500,064)	(199,472)
Residue Natural Gas Sales [Member]
Segment disclosure [Abstract]
Revenues	427,702	190,054
Residue Natural Gas Sales [Member] \| Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	312,247	189,051
Residue Natural Gas Sales [Member] \| Natural Gas Liquids
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Residue Natural Gas Sales [Member] \| Natural Gas Pipelines
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	115,455	2,035
Residue Natural Gas Sales [Member] \| Total Segments [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	427,702	191,086
Residue Natural Gas Sales [Member] \| Other and Eliminations
Segment disclosure [Abstract]
Revenues	0	(1,032)
Gathering, Processing and Exchange Services Revenue
Segment disclosure [Abstract]
Revenues	144,918	158,473
Gathering, Processing and Exchange Services Revenue \| Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	31,687	37,937
Gathering, Processing and Exchange Services Revenue \| Natural Gas Liquids
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	113,231	120,536
Gathering, Processing and Exchange Services Revenue \| Natural Gas Pipelines
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Gathering, Processing and Exchange Services Revenue \| Total Segments [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	144,918	158,473
Gathering, Processing and Exchange Services Revenue \| Other and Eliminations
Segment disclosure [Abstract]
Revenues	0	0
Transportation and Storage Revenue [Member]
Segment disclosure [Abstract]
Revenues	178,140	165,310
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
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	48,728	50,755
Transportation and Storage Revenue [Member] \| Natural Gas Pipelines
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	132,947	118,364
Transportation and Storage Revenue [Member] \| Total Segments [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	181,675	169,119
Transportation and Storage Revenue [Member] \| Other and Eliminations
Segment disclosure [Abstract]
Revenues	(3,535)	(3,809)
Other [Member]
Segment disclosure [Abstract]
Revenues	37,346	5,679
Other [Member] \| Natural Gas Gathering And Processing [Member]
Segment disclosure [Abstract]
Revenues	4,000	3,075
Other [Member] \| Natural Gas Liquids
Segment disclosure [Abstract]
Revenues	33,276	2,590
Other [Member] \| Natural Gas Pipelines
Segment disclosure [Abstract]
Revenues	412	384
Other [Member] \| Total Segments [Member]
Segment disclosure [Abstract]
Revenues	37,688	6,049
Other [Member] \| Other and Eliminations
Segment disclosure [Abstract]
Revenues	$ (342)	$ (370)