ONEOK Partners (OKS) 10-Q 5 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 27, 2015
Document Information [Line Items]
Entity Registrant Name	ONEOK Partners LP
Entity Central Index Key	909,281
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
Common Units [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		187,978,848
Class B Units [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		72,988,252

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues
Commodity sales	$ 1,722,254	$ 2,715,109	$ 3,157,970	$ 5,521,838
Services	405,253	350,626	774,296	706,200
Total revenues	2,127,507	3,065,735	3,932,266	6,228,038
Cost of sales and fuel	1,603,093	2,571,402	2,946,957	5,224,071
Net margin	524,414	494,333	985,309	1,003,967
Operating expenses
Operations and maintenance	143,131	142,664	298,252	273,182
Depreciation and amortization	86,199	71,447	172,046	138,182
General taxes	23,481	17,981	46,519	37,646
Total operating expenses	252,811	232,092	516,817	449,010
Gain (loss) on sale of assets	122	(16)	116	(1)
Operating income	271,725	262,225	468,608	554,956
Equity in net earnings from investments (Note I)	30,040	25,435	60,961	59,094
Allowance for equity funds used during construction	742	1,253	1,541	12,224
Other income	24	3,189	2,547	4,522
Other expense	(1,953)	(1,389)	(2,578)	(2,158)
Interest expense (net of capitalized interest of $9,927, $11,375, $17,157 and $27,143, respectively)	(86,492)	(73,008)	(167,201)	(141,284)
Income before income taxes	214,086	217,705	363,878	487,354
Income taxes	(2,476)	(3,194)	(5,236)	(7,375)
Net income	211,610	214,511	358,642	479,979
Less: Net income attributable to noncontrolling interest	1,840	77	3,278	153
Net income attributable to ONEOK Partners, L.P.	209,770	214,434	355,364	479,826
Limited partners' interest in net income:
Net income attributable to ONEOK Partners, L.P.	209,770	214,434	355,364	479,826
General partner's interest in net income	(95,989)	(84,669)	(188,790)	(161,901)
Limited partners' interest in net income	$ 113,781	$ 129,765	$ 166,574	$ 317,925
Limited partners' net income per unit, basic and diluted (Note H)	$ 0.44	$ 0.54	$ 0.65	$ 1.35
Number of units used in computation (thousands)	257,179	240,503	255,627	236,361

CONSOLIDATED STATEMENT OF INCOM

CONSOLIDATED STATEMENT OF INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Limited partners' net income per unit, diluted	$ 0.44	$ 0.54	$ 0.65	$ 1.35
Interest Costs, Capitalized During Period	$ 9,927	$ 11,375	$ 17,157	$ 27,143

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income	$ 211,610	$ 214,511	$ 358,642	$ 479,979
Other comprehensive income (loss)
Unrealized gains (losses) on risk-management assets/liabilities	17,981	(32,515)	5,424	(88,970)
Realized (gains) losses recognized in net income	(13,358)	7,834	(24,691)	36,842
Total other comprehensive income (loss)	4,623	(24,681)	(19,267)	(52,128)
Comprehensive income	216,233	189,830	339,375	427,851
Less: Comprehensive income attributable to noncontrolling interests	1,840	77	3,278	153
Comprehensive income attributable to ONEOK Partners, L.P.	$ 214,393	$ 189,753	$ 336,097	$ 427,698

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 53,125	$ 42,530
Accounts receivable, net	683,674	735,830
Affiliate receivables	1,790	8,553
Natural gas and natural gas liquids in storage	150,137	134,134
Commodity imbalances	31,246	64,788
Materials and supplies	60,505	55,833
Other current assets	56,811	44,385
Total current assets	1,037,288	1,086,053
Property, plant and equipment
Property, plant and equipment	13,949,876	13,377,617
Accumulated depreciation and amortization	1,995,905	1,842,084
Net property, plant and equipment	11,953,971	11,535,533
Investments and other assets
Investments in unconsolidated affiliates	1,146,407	1,132,653
Goodwill and intangible assets	830,827	822,358
Other assets	28,160	23,803
Total investments and other assets	2,005,394	1,978,814
Total assets	14,996,653	14,600,400
Current liabilities
Current maturities of long-term debt (Note E)	657,650	7,650
Notes payable (Note D)	870,484	1,055,296
Accounts payable	687,321	874,692
Affiliate payables	28,304	36,106
Commodity imbalances	91,605	104,650
Accrued interest	102,196	91,990
Other current liabilities	127,067	165,672
Total current liabilities	2,564,627	2,336,056
Long-term debt, excluding current maturities	6,145,972	6,004,232
Deferred credits and other liabilities	$ 146,320	$ 141,337
Commitments and contingencies (Note K)
ONEOK Partners, L.P. partners' equity:
General partner	$ 215,351	$ 211,914
Common units: 187,978,848 and 180,826,973 units issued and outstanding at June 30, 2015, and December 31, 2014, respectively	4,562,203	4,456,372
Class B units: 72,988,252 units issued and outstanding at June 30, 2015, and December 31, 2014	1,306,711	1,374,375
Accumulated other comprehensive loss (Note G)	(111,090)	(91,823)
Total ONEOK Partners, L.P. partners' equity	5,973,175	5,950,838
Noncontrolling interests in consolidated subsidiaries	166,559	167,937
Total equity	6,139,734	6,118,775
Total liabilities and equity	$ 14,996,653	$ 14,600,400

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares	Jun. 30, 2015	Dec. 31, 2014
ONEOK Partners, L.P. partners equity:
Common units issued (in shares)	187,978,848	180,826,973
Common units outstanding (in shares)	187,978,848	180,826,973
Class B units issued (in shares)	72,988,252	72,988,252
Class B units outstanding (in shares)	72,988,252	72,988,252

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating activities
Net income	$ 358,642	$ 479,979
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	172,046	138,182
Allowance for equity funds used during construction	(1,541)	(12,224)
Loss (gain) on sale of assets	(116)	1
Deferred income taxes	3,983	3,402
Equity in net earnings from investments	(60,961)	(59,094)
Distributions received from unconsolidated affiliates	61,969	61,200
Changes in assets and liabilities:
Accounts receivable	51,062	23,674
Affiliate receivables	6,763	845
Natural gas and natural gas liquids in storage	(16,003)	(146,830)
Accounts payable	(126,645)	68,045
Affiliate payables	(7,802)	(7,678)
Commodity imbalances, net	20,497	(18,710)
Accrued interest	10,206	(497)
Risk management assets and liabilities	(66,298)	(12,200)
Other assets and liabilities, net	(25,535)	15,983
Cash provided by operating activities	380,267	534,078
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	(628,396)	(792,414)
Cash paid for acquisitions	0	(14,000)
Contributions to unconsolidated affiliates	(33,222)	(1,063)
Distributions received from unconsolidated affiliates in excess of cumulative earnings	18,814	16,449
Proceeds from sale of assets	691	319
Other	(12,607)	0
Cash used in investing activities	(654,720)	(790,709)
Financing activities
Cash distributions paid to general and limited partners	(593,435)	(493,049)
Cash distributions paid to noncontrolling interests	(4,694)	(181)
Borrowing (repayment) of notes payable, net	(184,812)	0
Issuance of long-term debt, net of discounts	798,896	0
Debt financing costs	(7,850)	0
Repayment of long-term debt	(3,825)	(3,825)
Issuance of common units, net of issuance costs	275,098	878,765
Contribution from general partner	5,670	18,420
Cash provided by financing activities	285,048	400,130
Change in cash and cash equivalents	10,595	143,499
Cash and cash equivalents at beginning of period	42,530	134,530
Cash and cash equivalents at end of period	$ 53,125	$ 278,029

CONSOLIDATED STATEMENT OF CHANG

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - Jun. 30, 2015 - USD ($) $ in Thousands	Total	Common Units [Member]	Class B Units [Member]	General Partner [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests in Consolidated Subsidiaries [Member]
Partners capital account, units, beginning balance at Dec. 31, 2014		180,826,973	72,988,252
Partners capital account, beginning balance at Dec. 31, 2014	$ 6,118,775	$ 4,456,372	$ 1,374,375	$ 211,914	$ (91,823)	$ 167,937
Net income	358,642	118,918	47,656	188,790	0	3,278
Other comprehensive income (loss) (Note G)	(19,267)	$ 0	$ 0	0	(19,267)	0
Issuance of common units (in units) (Note F)		7,151,875	0
Issuance of common units (Note F)	273,991	$ 273,991	$ 0	0	0	0
Contribution from general partner (Note F)	5,684	0	0	5,684	0	0
Distributions paid (Note F)	(598,129)	(287,078)	(115,320)	(191,037)	0	(4,694)
Other	38	$ 0	$ 0	0	0	38
Partners capital account, units, ending balance at Jun. 30, 2015		187,978,848	72,988,252
Partners capital account, ending balance at Jun. 30, 2015	6,139,734	$ 4,562,203	$ 1,306,711	215,351	(111,090)	166,559
Partners capital account, beginning balance at Mar. 31, 2015	6,015,602					167,129
Net income	211,610					1,840
Other comprehensive income (loss) (Note G)	4,623					0
Issuance of common units (Note F)	203,454					0
Contribution from general partner (Note F)	4,584					0
Distributions paid (Note F)	(300,177)					(2,448)
Other	38					38
Partners capital account, units, ending balance at Jun. 30, 2015		187,978,848	72,988,252
Partners capital account, ending balance at Jun. 30, 2015	$ 6,139,734	$ 4,562,203	$ 1,306,711	$ 215,351	$ (111,090)	$ 166,559

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	A. 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 presentation of the results for the interim periods presented. All such adjustments are of a normal recurring nature. The 2014 year-end consolidated balance sheet data was derived from our audited financial statements but does not include all disclosures required by GAAP. These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements in our Annual Report. Our significant accounting policies are consistent with those disclosed in Note A of the Notes to Consolidated Financial Statements in our Annual Report. In November 2014 , we completed the acquisition of an 80 percent interest in the West Texas LPG Pipeline Limited Partnership and a 100 percent interest in the Mesquite Pipeline for approximately $800 million from affiliates of Chevron Corporation. We accounted for this acquisition as a business combination that, among other things, requires assets acquired and liabilities assumed to be measured at their acquisition-date fair values. Our consolidated balance sheets as of June 30, 2015 , and December 31, 2014 , reflect the preliminary purchase price allocation based on available information, which is subject to customary adjustments, including working capital. We are reviewing the valuation to determine the final purchase price allocation. See Note B in the Notes to Consolidated Financial Statements in our Annual Report for additional information on this acquisition. Recently Issued Accounting Standards Update - In March 2015, the FASB issued ASU 2015-03, “Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs,” which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. This guidance is effective for public companies for fiscal years beginning after December 15, 2015, with early adoption permitted. We elected to adopt this guidance early beginning in the second quarter 2015. Retrospective adjustment of prior periods presented is required. Therefore, the December 31, 2014, balance sheet has been recast to reclassify $34.1 million of debt issuance costs from other assets to long-term debt. The impact of adopting this guidance was not material. In April 2014, the FASB issued ASU 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity,” which alters the definition of a discontinued operation to include only asset disposals that represent a strategic shift with a major effect on an entity’s operations and financial results. The amendment also requires more extensive disclosures about a discontinued operation’s assets, liabilities, income, expenses and cash flows. This guidance will be effective for interim and annual periods for all assets that are disposed of or classified as being held for sale in fiscal years that begin on or after December 15, 2014. We adopted this guidance beginning in the first quarter 2015, and it could impact us in the future if we dispose of any individually significant components. In April 2015, the FASB issued ASU 2015-05, “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement,” which clarifies whether a cloud computing arrangement includes a software license. If it does, the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses; if not, the customer should not account for the arrangement as a service contract. This guidance is effective for public companies for fiscal years beginning after December 15, 2015. Early adoption is permitted. We expect to adopt this guidance in the first quarter 2016, and we do not expect it to materially impact us. In February 2015, the FASB issued ASU 2015-02, “Consolidation (Topic 810): Amendments to the Consolidation Analysis,” which eliminates the presumption that a general partner should consolidate a limited partnership. It also modifies the evaluation of whether limited partnerships are variable interest entities or voting interest entities and adds requirements that limited partnerships must meet to qualify as voting interest entities. This guidance is effective for public companies for fiscal years beginning after December 15, 2015. We expect to adopt this guidance in the first quarter 2016, and we are evaluating the impact on us. In August 2014, the FASB issued ASU 2014-15, “Going Concern,” which provides guidance on determining when and how to disclose going-concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if conditions or events raise substantial doubt about the entity’s ability to continue as a going concern. The standard applies to all entities and is effective for annual periods ending after December 15, 2016, and interim periods thereafter, with early adoption permitted. We expect to adopt this guidance beginning in the first quarter 2016, and we do not expect it to materially impact us. In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers,” which outlines the principles an entity must apply to measure and recognize revenue for entities that enter into contracts to provide goods or services to their customers. The core principle is that an entity should recognize revenue at an amount that reflects the consideration to which the entity expects to be entitled in exchange for transferring goods or services to a customer. The amendment also requires more extensive disaggregated revenue disclosures in interim and annual financial statements. In July 2015, the FASB announced it has deferred the effective date by one year. This update is now effective for interim and annual periods that begin after December 15, 2017, with either retrospective application for all periods presented or retrospective application with a cumulative effect adjustment. We expect to adopt this guidance beginning in the first quarter 2018, and we are evaluating the impact on us.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	B. FAIR VALUE MEASUREMENTS Determining Fair Value - We define fair value as the price that would be received from the sale of an asset or the transfer of a liability in an orderly transaction between market participants at the measurement date. We use market and income approaches to determine the fair value of our assets and liabilities and consider the markets in which the transactions are executed. We measure the fair value of a group of financial assets and liabilities consistent with how a market participant would price the net risk exposure at the measurement date. While many of the contracts in our portfolio are executed in liquid markets where price transparency exists, some contracts are executed in markets for which market prices may exist, but the market may be relatively inactive. This results in limited price transparency that requires management’s judgment and assumptions to estimate fair values. For certain transactions, we utilize modeling techniques using NYMEX-settled pricing data and implied forward LIBOR curves. Inputs into our fair value estimates include commodity-exchange prices, over-the-counter quotes, historical correlations of pricing data, data obtained from third-party pricing services and LIBOR and other liquid money-market instrument rates. We validate our valuation inputs with third-party information and settlement prices from other sources, where available. In addition, as prescribed by the income approach, we compute the fair value of our derivative portfolio by discounting the projected future cash flows from our derivative assets and liabilities to present value using interest-rate yields to calculate present-value discount factors derived from LIBOR, Eurodollar futures and interest-rate swaps. We also take into consideration the potential impact on market prices of liquidating positions in an orderly manner over a reasonable period of time under current market conditions. We consider current market data in evaluating counterparties’, as well as our own, nonperformance risk, net of collateral, by using specific and sector bond yields and monitoring the credit default swap markets. Although we use our best estimates to determine the fair value of the derivative contracts we have executed, the ultimate market prices realized could differ from our estimates, and the differences could be material. The fair value of our forward-starting interest-rate swaps are determined using financial models that incorporate the implied forward LIBOR yield curve for the same period as the future interest swap settlements. Fair Value Hierarchy - At each balance sheet date, we utilize a fair value hierarchy to classify fair value amounts recognized or disclosed in our financial statements based on the observability of inputs used to estimate such fair value. The levels of the hierarchy are described below: • Level 1 - fair value measurements are based on unadjusted quoted prices for identical securities in active markets, including NYMEX-settled prices. These balances are comprised predominantly of exchange-traded derivative contracts for natural gas and crude oil. • Level 2 - fair value measurements are based on significant observable pricing inputs, such as NYMEX-settled prices for natural gas and crude oil, and financial models that utilize implied forward LIBOR yield curves for interest-rate swaps. • Level 3 - fair value measurements are based on inputs that may include one or more unobservable inputs, including natural gas basis and NGL price curves that incorporate observable and unobservable market data from broker quotes, third-party pricing services , market volatilities derived from the most recent NYMEX close spot prices and forward LIBOR curves, and adjustments for the credit risk of our counterparties. We corroborate the data on which our fair value estimates are based using our market knowledge of recent transactions, analysis of historical correlations and validation with independent broker quotes. These balances categorized as Level 3 are comprised of derivatives for natural gas and NGLs. We do not believe that our Level 3 fair value estimates have a material impact on our results of operations, as the majority of our derivatives are accounted for as hedges for which ineffectiveness has not been material. 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: June 30, 2015 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net (b) ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 24,510 $ — $ 6,832 $ 31,342 $ (12,867 ) $ 18,475 Physical contracts — — 6,448 6,448 — 6,448 Interest-rate contracts — 6,961 — 6,961 — 6,961 Total derivative assets $ 24,510 $ 6,961 $ 13,280 $ 44,751 $ (12,867 ) $ 31,884 Derivative liabilities Commodity contracts Financial contracts $ (4,475 ) $ — $ (2,639 ) $ (7,114 ) $ 7,114 $ — Physical contracts — — (254 ) (254 ) — (254 ) Total derivative liabilities $ (4,475 ) $ — $ (2,893 ) $ (7,368 ) $ 7,114 $ (254 ) (a) - Our derivative assets and liabilities are presented in our Consolidated Balance Sheets on a net basis. We net derivative assets and liabilities when a legally enforceable master-netting arrangement exists between the counterparty to a derivative contract and us. At June 30, 2015 , we had $5.8 million of cash held from various counterparties and no cash collateral posted. (b) - Included in other current assets, other assets, other current liabilities or deferred credits and other liabilities in our Consolidated Balance Sheets. December 31, 2014 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net (b) ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 42,880 $ — $ 354 $ 43,234 $ (25,979 ) $ 17,255 Physical contracts — — 9,922 9,922 — 9,922 Interest-rate contracts — 2,288 — 2,288 — 2,288 Total derivative assets $ 42,880 $ 2,288 $ 10,276 $ 55,444 $ (25,979 ) $ 29,465 Derivative liabilities Commodity contracts Financial contracts $ (169 ) $ — $ (968 ) $ (1,137 ) $ 1,137 $ — Physical contracts — — (23 ) (23 ) — (23 ) Interest-rate contracts — (44,843 ) — (44,843 ) — (44,843 ) Total derivative liabilities $ (169 ) $ (44,843 ) $ (991 ) $ (46,003 ) $ 1,137 $ (44,866 ) (a) - Our derivative assets and liabilities are presented in our Consolidated Balance Sheets on a net basis. We net derivative assets and liabilities when a legally enforceable master-netting arrangement exists between the counterparty to a derivative contract and us. At December 31, 2014, we had $24.8 million of cash held from various counterparties and no cash collateral posted. (b) - Included in other current assets, other assets or other current liabilities in our Consolidated Balance Sheets. The following table sets forth a reconciliation of our Level 3 fair value measurements for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, Derivative Assets (Liabilities) 2015 2014 2015 2014 ( Thousands of dollars ) Net assets (liabilities) at beginning of period $ 7,040 $ 1,972 $ 9,285 $ (782 ) Total realized/unrealized gains (losses): Included in earnings (a) (159 ) 33 110 (895 ) Included in other comprehensive income (loss) 3,506 (3,318 ) 992 (3,370 ) Purchases, issuances and settlements — — — 3,734 Net assets (liabilities) at end of period $ 10,387 $ (1,313 ) $ 10,387 $ (1,313 ) (a) - Included in commodity sales revenues in our Consolidated Statements of Income. Realized/unrealized gains (losses) include the realization of our derivative contracts through maturity. During the three and six months ended June 30, 2015 and 2014 , gains or losses included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the end of each reporting period were not material. We recognize transfers into and out of the levels in the fair value hierarchy as of the end of each reporting period. During the three and six months ended June 30, 2015 and 2014 , there were no transfers between levels. Other Financial Instruments - The approximate fair value of cash and cash equivalents, accounts receivable, accounts payable and notes payable is equal to book value, due to the short-term nature of these items. Our cash and cash equivalents are comprised of bank and money market accounts and are classified as Level 1. Our notes payable are classified as Level 2 since the estimated fair value of the notes payable can be determined using information available in the commercial paper market. The estimated fair value of the aggregate of our senior notes outstanding, including current maturities, was $7.0 billion and $6.4 billion at June 30, 2015 , and December 31, 2014 , respectively. The book value of the aggregate of our senior notes outstanding, including current maturities, was $6.8 billion and $6.0 billion at June 30, 2015 , and December 31, 2014 , respectively. The estimated fair value of the aggregate of our senior notes outstanding was determined using quoted market prices for similar issues with similar terms and maturities. The estimated fair value of our long-term debt is classified as Level 2.

RISK MANAGEMENT AND HEDGING ACT

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES	C. 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 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 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. We are also subject to the risk of interest-rate fluctuation in the normal course of business. Commodity price risk - Commodity price risk refers to the risk of loss in cash flows and future earnings arising from adverse changes in the price of natural gas, NGLs and condensate. We use the following commodity derivative instruments to mitigate 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; and • 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. We may also use other instruments including options or collars to mitigate commodity price risk. Options are 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. 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 receiving commodities in exchange for services associated with our POP contracts. We also are exposed to basis risk between the various production and market locations where we receive 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 exposed to location price differential risk, primarily as a result of the relative value of NGL purchases at one location and sales at another location. We are also exposed to commodity price risk resulting from the relative values of the various NGL products to each other, NGLs in storage and the relative value of NGLs to natural gas. We utilize physical-forward contracts and commodity derivative financial instruments to reduce the impact of price fluctuations related to NGLs. In our Natural Gas Pipelines segment, we are exposed to commodity price risk because our intrastate and interstate natural gas pipelines retain natural gas from our customers for operations or as part of our fee for services provided. When the amount of natural gas consumed in operations by these pipelines differs from the amount provided by our customers, our pipelines must buy or sell natural gas, or store or use natural gas from inventory, which can expose us 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 use physical-forward sales or purchases to reduce the impact of price fluctuations related to natural gas. At June 30, 2015 , and December 31, 2014 , 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 December 31, 2014 , we had forward-starting interest-rate swaps with notional amounts totaling $900 million that were designated as cash flow hedges of the variability of interest payments on a portion of forecasted debt issuances that may result from changes in the benchmark interest rate before the debt is issued. Upon our debt issuance in March 2015, we settled $500 million of our interest-rate swaps and realized a loss of $55.1 million , which is included in accumulated other comprehensive loss and will be amortized to interest expense over the term of the related debt. At June 30, 2015 , our remaining interest-rate swaps with notional amounts totaling $400 million have settlement dates greater than 12 months. Accounting Treatment - We record all derivative instruments at fair value, with the exception of normal purchases and normal sales transactions that are expected to result in physical delivery. Commodity price and interest-rate volatility may have a significant impact on the fair value of derivative instruments as of a given date. The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and, if so, the reason for holding it. The table below summarizes the various ways in which we account for our derivative instruments and the impact on our consolidated financial statements: Recognition and Measurement Accounting Treatment Balance Sheet Income Statement Normal purchases and normal sales - Fair value not recorded - Change in fair value not recognized in earnings Mark-to-market - Recorded at fair value - Change in fair value recognized in earnings Cash flow hedge - Recorded at fair value - Ineffective portion of the gain or loss on the derivative instrument is recognized in earnings - Effective portion of the gain or loss on the derivative instrument is reported initially as a component of accumulated other comprehensive income (loss) - Effective portion of the gain or loss on the derivative instrument is reclassified out of accumulated other comprehensive income (loss) into earnings when the forecasted transaction affects earnings Fair value hedge - Recorded at fair value - The gain or loss on the derivative instrument is recognized in earnings - Change in fair value of the hedged item is recorded as an adjustment to book value - Change in fair value of the hedged item is recognized in earnings To reduce our exposure to fluctuations in natural gas, NGLs and condensate prices, we periodically enter into futures, forward purchases and sales, options or swap transactions in order to hedge anticipated purchases and sales of natural gas, NGLs and condensate. Interest-rate swaps are used from time to time to manage interest-rate risk. Under certain conditions, we designate our derivative instruments as a hedge of exposure to changes in fair values or cash flows. We formally document all relationships between hedging instruments and hedged items, as well as risk-management objectives and strategies for undertaking various hedge transactions, and methods for assessing and testing correlation and hedge ineffectiveness. We specifically identify the forecasted transaction that has been designated as the hedged item in a cash flow hedge relationship. We assess the effectiveness of hedging relationships quarterly by performing an effectiveness analysis on our fair value and cash flow hedging relationships to determine whether the hedge relationships are highly effective on a retrospective and prospective basis. We also document our normal purchases and normal sales transactions that we expect to result in physical delivery and that we elect to exempt from derivative accounting treatment. The realized revenues and purchase costs of our derivative instruments not considered held for trading purposes and derivatives that qualify as normal purchases or normal sales that are expected to result in physical delivery are reported on a gross basis. Cash flows from futures, forwards and swaps that are accounted for as hedges are included in the same category as the cash flows from the related hedged items in our Consolidated Statements of Cash Flows. 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 for the periods indicated: June 30, 2015 December 31, 2014 Assets (a) (Liabilities) (a) Assets (a) (Liabilities) (a) ( Thousands of dollars ) Derivatives designated as hedging instruments Commodity contracts Financial contracts $ 30,656 $ (6,779 ) $ 43,234 $ (1,137 ) Physical contracts 6,448 (254 ) 9,922 — Interest-rate contracts 6,961 — 2,288 (44,843 ) Total derivatives designated as hedging instruments 44,065 (7,033 ) 55,444 (45,980 ) Derivatives not designated as hedging instruments Commodity contracts Financial contracts 686 (335 ) — — Physical contracts — — — (23 ) Total derivatives not designated as hedging instruments 686 (335 ) — (23 ) Total derivatives $ 44,751 $ (7,368 ) $ 55,444 $ (46,003 ) (a) - Included on a net basis in other current assets, other assets, other current liabilities or deferred credits and other liabilities in our Consolidated Balance Sheets. Notional Quantities for Derivative Instruments - The following table sets forth the notional quantities for derivative instruments held for the periods indicated: June 30, 2015 December 31, 2014 Contract Type Purchased/ Payor Sold/ Receiver Purchased/ Payor Sold/ Receiver Derivatives designated as hedging instruments: Cash flow hedges Fixed price - Natural gas ( Bcf ) Futures and swaps — (62.1 ) — (41.2 ) - Crude oil and NGLs ( MMBbl ) Futures, forwards and swaps — (4.9 ) — (0.5 ) Basis - Natural gas ( Bcf ) Futures and swaps — (62.1 ) — (41.2 ) Interest-rate contracts ( Millions of dollars ) Forward-starting swaps $ 400.0 $ — $ 900.0 $ — Derivatives not designated as hedging instruments: Fixed price - Crude oil and NGLs ( MMBbl ) Futures, forwards and swaps 0.6 (0.6 ) — — These notional amounts are used to summarize the volume of financial instruments; however, they do not reflect the extent to which the positions offset one another and, consequently, do not reflect our actual exposure to market or credit risk. Cash Flow Hedges - At June 30, 2015 , our Consolidated Balance Sheet reflected a net loss of $111.1 million in accumulated other comprehensive loss. The portion of accumulated other comprehensive loss attributable to our commodity derivative financial instruments is an unrealized gain of $32.4 million , which will be realized within the next 18 months as the forecasted transactions affect earnings. If commodity prices remain at the current levels, we will realize $30.4 million in net gains over the next 12 months and $2.0 million in net gains thereafter. The amount deferred in accumulated other comprehensive loss attributable to our settled interest-rate swaps is a loss of $149.2 million , which will be recognized over the life of the long-term, fixed-rate debt, including losses of $15.5 million , which will be reclassified into earnings during the next 12 months as the hedged items affect earnings. The remaining amounts in accumulated other comprehensive loss are attributable primarily to forward-starting interest-rate swaps with future settlement dates, which will be amortized to interest expense over the life of long-term, fixed-rate debt upon issuance of the debt. The following table sets forth the unrealized effect of cash flow hedges recognized in other comprehensive income (loss) for the periods indicated: Three Months Ended Six Months Ended Derivatives in Cash Flow Hedging Relationships June 30, June 30, 2015 2014 2015 2014 ( Thousands of dollars ) Commodity contracts $ 1,072 $ (6,114 ) $ 11,091 $ (41,876 ) Interest-rate contracts 16,909 (26,401 ) (5,667 ) (47,094 ) Total unrealized gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion) $ 17,981 $ (32,515 ) $ 5,424 $ (88,970 ) The following table sets forth the effect of cash flow hedges in our Consolidated Statements of Income for the periods indicated: Derivatives in Cash Flow Hedging Relationships Location of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Net Income (Effective Portion) Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands of dollars ) Commodity contracts Commodity sales revenues $ 17,078 $ (5,187 ) $ 31,250 $ (31,606 ) Interest-rate contracts Interest expense (3,720 ) (2,647 ) (6,559 ) (5,236 ) Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion) $ 13,358 $ (7,834 ) $ 24,691 $ (36,842 ) Ineffectiveness related to our cash flow hedges was not material for the three and six months ended June 30, 2015 and 2014 . In the event that it becomes probable that a forecasted transaction will not occur, we would discontinue cash flow hedge treatment, which would affect earnings. There were no gains or losses due to the discontinuance of cash flow hedge treatment during the three and six months ended June 30, 2015 and 2014 . 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 have counterparties whose credit is not rated, and for those customers, we use internally developed credit ratings. Some of our financial derivative instruments contain provisions that require us to maintain an investment-grade credit rating from S&P and/or Moody’s. If our credit ratings on our senior unsecured long-term debt were to decline below investment grade, the counterparties to the derivative instruments could request collateralization on derivative instruments in net liability positions. There were no financial derivative instruments with contingent features related to credit risk that were in a net liability position at June 30, 2015 . The counterparties to our derivative contracts consist primarily 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 June 30, 2015 , the net credit exposure from our derivative assets is primarily with investment-grade companies in the financial services sector.

CREDIT FACILITY AND SHORT-TERM

CREDIT FACILITY AND SHORT-TERM NOTES PAYABLE	6 Months Ended
	Jun. 30, 2015
Short-term Debt [Abstract]
CREDIT FACILITY AND SHORT-TERM NOTES PAYABLE	D. CREDIT FACILITY AND SHORT-TERM NOTES PAYABLE Partnership Credit Agreement - At June 30, 2015 , we had $870.5 million of commercial paper outstanding, $14.0 million in letters of credit issued and no borrowings under our Partnership Credit Agreement. Our Partnership Credit Agreement, which is scheduled to expire in January 2019, is a $2.4 billion revolving credit facility and includes a $100 million sublimit for the issuance of standby letters of credit and a $150 million swingline sublimit. Our Partnership Credit Agreement is available for general partnership purposes. During the first quarter 2015, we increased the size of our Partnership Credit Agreement to $2.4 billion from $1.7 billion by exercising our option to increase the capacity of the facility through increased commitments from existing lenders and a commitment from one new lender. During the first quarter 2015, we also increased the size of our commercial paper program to $2.4 billion from $1.7 billion . Amounts outstanding under our commercial paper program reduce the borrowing capacity under our Partnership Credit Agreement. Our Partnership Credit Agreement contains provisions for an applicable margin rate and an annual facility fee, both of which adjust with changes in our credit rating. Under the terms of the Partnership Credit Agreement, based on our current credit ratings, borrowings, if any, will accrue at LIBOR plus 117.5 basis points , and the annual facility fee is 20 basis points . Our Partnership Credit Agreement is guaranteed fully and unconditionally by the Intermediate Partnership. Borrowings under our Partnership Credit Agreement are nonrecourse to ONEOK. Our Partnership Credit Agreement 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 Partnership Credit Agreement, adjusted for all noncash charges and increased for projected EBITDA from certain lender-approved capital expansion projects) of no more than 5.0 to 1. If we consummate one or more acquisitions in which the aggregate purchase price is $25 million or more, the allowable ratio of indebtedness to adjusted EBITDA will increase to 5.5 to 1 for the quarter in which the acquisition was completed and the two following quarters. As a result of the West Texas LPG acquisition we completed in the fourth quarter 2014, the allowable ratio of indebtedness to adjusted EBITDA increased to 5.5 to 1 through the second quarter 2015. If we were to breach certain covenants in our Partnership Credit Agreement, amounts outstanding under it, if any, may become due and payable immediately. At June 30, 2015 , our ratio of indebtedness to adjusted EBITDA was 4.5 to 1, and we were in compliance with all covenants under our Partnership Credit Agreement. Neither we nor ONEOK guarantees the debt or other similar commitments of unaffiliated parties. ONEOK does not guarantee the debt, commercial paper or other similar commitments of ONEOK Partners, and ONEOK Partners does not guarantee the debt or other similar commitments of ONEOK.

LONG TERM DEBT LONG-TERM DEBT (

LONG TERM DEBT LONG-TERM DEBT (Notes)	6 Months Ended
	Jun. 30, 2015
Debt Instrument [Line Items]
Long-term Debt [Text Block]	E. LONG-TERM DEBT In March 2015, we completed an underwritten public offering of $800 million of senior notes, consisting of $300 million , 3.8 percent senior notes due 2020, and $500 million , 4.9 percent senior notes due 2025. The net proceeds, after deducting underwriting discounts, commissions and other expenses, were approximately $792.3 million . We used the proceeds to repay amounts outstanding under our commercial paper program and for general partnership purposes. These notes are governed by an indenture, dated September 25, 2006, between us and Wells Fargo Bank, N.A., the trustee, as supplemented. The indenture does not limit the aggregate principal amount of debt securities that may be issued and provides that debt securities may be issued from time to time in one or more additional series. The indenture contains covenants including, among other provisions, limitations on our ability to place liens on our property or assets and to sell and lease back our property. The indenture includes an event of default upon acceleration of other indebtedness of $100 million or more. Such events of default would entitle the trustee or the holders of 25 percent in aggregate principal amount of any of our outstanding senior notes to declare those notes immediately due and payable in full. We may redeem our 3.8 percent senior notes due 2020 and our 4.9 percent senior notes due 2025 from the March 2015 offering at par, plus accrued and unpaid interest to the redemption date, starting one month and three months, respectively, before their maturity dates. Prior to these dates, we may redeem these notes, in whole or in part, at a redemption price equal to the principal amount, plus accrued and unpaid interest and a make-whole premium. The redemption price will never be less than 100 percent of the principal amount of the respective note plus accrued and unpaid interest to the redemption date. Our senior notes are senior unsecured obligations, ranking equally in right of payment with all of our existing and future unsecured senior indebtedness, and structurally subordinate to any of the existing and future debt and other liabilities of any nonguarantor subsidiaries. Our $650 million , 3.25 percent senior notes mature on February 1, 2016. The carrying amount of these notes is reflected in current portion of long-term debt in our Consolidated Balance Sheet as of June 30, 2015 .

EQUITY

EQUITY	6 Months Ended
	Jun. 30, 2015
Equity [Abstract]
EQUITY	F. EQUITY ONEOK - ONEOK and its affiliates owned all of the Class B units, 19.8 million common units and the entire 2 percent general partner interest in us, which together constituted a 36.8 percent ownership interest in us at June 30, 2015 . Equity Issuances - We have an “at-the-market” equity program for the offer and sale from time to time of our common units, up to an aggregate amount of $650 million . The program allows us to offer and sell our common units at prices we deem appropriate through a sales agent. Sales of common units are made by means of ordinary brokers’ transactions on the NYSE, in block transactions or as otherwise agreed to between us and the sales agent. We are under no obligation to offer and sell common units under the program. At June 30, 2015 , we had approximately $238 million of registered common units available for issuance under our “at-the-market” equity program. During the three months ended June 30, 2015 , we sold approximately 5.5 million common units through our “at-the-market” equity program. The net proceeds, including ONEOK Partners GP’s contribution to maintain its 2 percent general partner interest in us, were approximately $208.1 million , which were used for general partnership purposes, including repayment of commercial paper borrowings. During the six months ended June 30, 2015 , we sold approximately 7.2 million common units through our “at-the-market” equity program. The net proceeds, including ONEOK Partners GP’s contribution to maintain its 2 percent general partner interest in us, were approximately $279.7 million , which were used for general partnership purposes, including repayment of commercial paper borrowings. As a result of these transactions, ONEOK’s aggregate ownership interest in us decreased to 36.8 percent at June 30, 2015 , from 37.8 percent at December 31, 2014 . In May 2014, we completed an underwritten public offering of approximately 13.9 million common units at a public offering price of $52.94 per common unit, generating net proceeds of approximately $714.5 million . In conjunction with this issuance, ONEOK Partners GP contributed approximately $15.0 million in order to maintain its 2 percent general partner interest in us. We used the proceeds for general partnership purposes, including capital expenditures and repayment of commercial paper borrowings. During the three months ended June 30, 2014 , we sold approximately 1.9 million common units through our “at-the-market” equity program. The net proceeds, including ONEOK Partners GP’s contribution to maintain its 2 percent general partner interest in us, were approximately $107.6 million , which were used for general partnership purposes. During the six months ended June 30, 2014 , we sold approximately 3.0 million common units through our “at-the-market” equity program. The net proceeds, including ONEOK Partners GP’s contribution to maintain its 2 percent general partner interest in us, were approximately $164.1 million , which were used for general partnership purposes. Partnership Agreement - Available cash, as defined in our Partnership Agreement, generally will be distributed to our general partner and limited partners according to their partnership percentages of 2 percent and 98 percent, respectively. Our general partner’s percentage interest in quarterly distributions is increased after certain specified target levels are met during the quarter. Under the incentive distribution provisions, as set forth in our Partnership Agreement, our general partner receives: • 15 percent of amounts distributed in excess of $0.3025 per unit; • 25 percent of amounts distributed in excess of $0.3575 per unit; and • 50 percent of amounts distributed in excess of $0.4675 per unit. Cash Distributions - In July 2015 , our general partner declared a cash distribution of $0.79 per unit ( $3.16 per unit on an annualized basis) for the second quarter 2015 , which will be paid on August 14, 2015 , to unitholders of record at the close of business on August 3, 2015 . The following table shows our distributions paid during the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands, except per unit amounts ) Distribution per unit $ 0.79 $ 0.745 $ 1.58 $ 1.475 General partner distributions $ 5,955 $ 5,011 $ 11,869 $ 9,860 Incentive distributions 89,889 71,911 179,168 140,166 Distributions to general partner 95,844 76,922 191,037 150,026 Limited partner distributions to ONEOK 73,302 69,125 146,604 136,862 Limited partner distributions to other unitholders 128,583 104,506 255,794 206,161 Total distributions paid $ 297,729 $ 250,553 $ 593,435 $ 493,049 Distributions are declared and paid within 45 days of the completion of each quarter. The following table shows our distributions declared for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands, except per unit amounts ) Distribution per unit $ 0.79 $ 0.760 $ 1.58 $ 1.505 General partner distributions $ 6,081 $ 5,501 $ 12,036 $ 10,512 Incentive distributions 91,794 80,381 181,683 152,292 Distributions to general partner 97,875 85,882 193,719 162,804 Limited partner distributions to ONEOK 73,302 70,519 146,604 139,646 Limited partner distributions to other unitholders 132,862 118,644 261,445 223,150 Total distributions declared $ 304,039 $ 275,045 $ 601,768 $ 525,600 Noncontrolling Interest - In November 2014, we completed the acquisition of an 80 percent interest in the West Texas LPG Pipeline Limited Partnership (WTLPG). We consolidate WTLPG as we control the system. We have recorded noncontrolling interests in consolidated subsidiaries on our consolidated financial statements to recognize the portion of WTLPG that we do not own. Prior to November 2014, our noncontrolling interests in consolidated subsidiaries were not material. The following table sets forth the changes in equity attributable to us and our noncontrolling interests, including other comprehensive income, net of tax, for the periods indicated: Three Months Ended Six Months Ended June 30, 2015 June 30, 2015 ONEOK Partners, L.P. Partners ’ Equity Noncontrolling Interests in Consolidated Subsidiaries Total Equity ONEOK Partners, L.P. Partners ’ Equity Noncontrolling Interests in Consolidated Subsidiaries Total Equity ( Thousands of dollars ) Beginning balance $ 5,848,473 $ 167,129 $ 6,015,602 $ 5,950,838 $ 167,937 $ 6,118,775 Net income 209,770 1,840 211,610 355,364 3,278 358,642 Other comprehensive income (loss) 4,623 — 4,623 (19,267 ) — (19,267 ) Issuance of common units 203,454 — 203,454 273,991 — 273,991 Contribution from general partner 4,584 — 4,584 5,684 — 5,684 Distributions paid (297,729 ) (2,448 ) (300,177 ) (593,435 ) (4,694 ) (598,129 ) Other — 38 38 — 38 38 Ending balance $ 5,973,175 $ 166,559 $ 6,139,734 $ 5,973,175 $ 166,559 $ 6,139,734

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ACCUMULATED OTHER COMPREHENSIVE INCOME (Notes)	6 Months Ended
	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	G. ACCUMULATED OTHER COMPREHENSIVE LOSS The following table sets forth the balance in accumulated other comprehensive loss for the period indicated: Accumulated Other Comprehensive Loss (a) ( Thousands of dollars ) January 1, 2015 $ (91,823 ) Other comprehensive loss before reclassifications 5,424 Amounts reclassified from accumulated other comprehensive loss (24,691 ) Net current-period other comprehensive loss attributable to ONEOK Partners (19,267 ) June 30, 2015 $ (111,090 ) (a) - All amounts are attributable to unrealized losses in risk-management assets/liabilities. The following table sets forth the effect of reclassifications from accumulated other comprehensive income (loss) in our Consolidated Statements of Income for the periods indicated: Details about Accumulated Other Components Three Months Ended June 30, Six Months Ended June 30, Affected Line Item in the Income 2015 2014 2015 2014 ( Thousands of dollars ) Unrealized (gains) losses on risk-management assets/liabilities Commodity contracts $ (17,078 ) $ 5,187 $ (31,250 ) $ 31,606 Commodity sales revenues Interest-rate contracts 3,720 2,647 6,559 5,236 Interest expense Total reclassifications for the period attributable to ONEOK Partners $ (13,358 ) $ 7,834 $ (24,691 ) $ 36,842 Net income attributable to ONEOK Partners

LIMITED PARTNERS' NET INCOME PE

LIMITED PARTNERS' NET INCOME PER UNIT	6 Months Ended
	Jun. 30, 2015
Limited Partners' Net Income Per Unit and Distributions to Partners [Abstract]
LIMITED PARTNERS' NET INCOME PER UNIT	H. LIMITED PARTNERS’ NET INCOME PER UNIT Limited partners’ net income per unit is computed by dividing net income attributable to ONEOK Partners, L.P., after deducting the general partner’s allocation as discussed below, by the weighted-average number of outstanding limited partner units, which includes our common and Class B limited partner units. Because ONEOK has conditionally waived its right to increased quarterly distributions, until it gives 90 days notice of the withdrawal of the waiver, currently each Class B and common unit share equally in the earnings of the partnership, and neither has any liquidation or other preferences. ONEOK Partners GP owns the entire 2 percent general partnership interest in us, which entitles it to incentive distribution rights that provide for an increasing proportion of cash distributions from the Partnership as the distributions made to limited partners increase above specified levels. For purposes of our calculation of limited partners’ net income per unit, net income attributable to ONEOK Partners, L.P. is allocated to the general partner as follows: (i) an amount based upon the 2 percent general partner interest in net income attributable to ONEOK Partners, L.P.; and (ii) the amount of the general partner’s incentive distribution rights based on the total cash distributions declared for the period. The terms of our Partnership Agreement limit the general partner’s incentive distribution to the amount of available cash calculated for the period. As such, incentive distribution rights are not allocated on undistributed earnings. For additional information regarding our general partner’s incentive distribution rights, see “Partnership Agreement” in Note I of the Notes to Consolidated Financial Statements in our Annual Report.

UNCONSOLIDATED AFFILIATES

UNCONSOLIDATED AFFILIATES	6 Months Ended
	Jun. 30, 2015
Equity Method Investments and Joint Ventures [Abstract]
UNCONSOLIDATED AFFILIATES	I. UNCONSOLIDATED AFFILIATES Equity in Net Earnings from Investments - The following table sets forth our equity in net earnings from investments for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands of dollars ) Share of investee earnings Northern Border Pipeline $ 15,273 $ 15,877 $ 34,975 $ 39,286 Overland Pass Pipeline Company 9,623 4,121 16,510 8,852 Other 5,144 5,437 9,476 10,956 Equity in net earnings from investments $ 30,040 $ 25,435 $ 60,961 $ 59,094 Unconsolidated Affiliates Financial Information - The following table sets forth summarized combined financial information of our unconsolidated affiliates for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands of dollars ) Income Statement Operating revenues $ 125,738 $ 121,509 $ 255,319 $ 276,788 Operating expenses $ 55,959 $ 51,870 $ 113,538 $ 123,549 Net income $ 62,643 $ 60,878 $ 129,002 $ 139,551 Distributions paid to us $ 41,354 $ 42,579 $ 80,783 $ 77,649 We incurred expenses in transactions with unconsolidated affiliates of $25.9 million and $14.3 million for the three months ended June 30, 2015 and 2014 , respectively, and $45.8 million and $28.4 million for the six months ended June 30, 2015 and 2014 , respectively, primarily related to Overland Pass Pipeline Company and Northern Border Pipeline Company. Accounts payable to our equity method investees at June 30, 2015 , and December 31, 2014 , were $10.1 million and $20.5 million , respectively. Roadrunner Gas Transmission - In March 2015, we entered into a 50-50 joint venture named Roadrunner Gas Transmission (Roadrunner) with a subsidiary of Fermaca Infrastructure B.V. (Fermaca), a Mexico City-based natural gas infrastructure company, to construct a pipeline to transport natural gas from the Permian Basin in West Texas to the Mexican border near El Paso, Texas. During the second quarter 2015, we contributed approximately $33.2 million to Roadrunner. Powder River Basin Equity Method Investments - Crude oil and natural gas producers have primarily focused their development efforts on crude oil and NGL-rich supply basins rather than areas with dry natural gas production, such as the coal-bed methane areas in the Powder River Basin. The reduced coal-bed methane development activities and natural production declines in the dry natural gas formations of the Powder River Basin have resulted in lower natural gas volumes available to be gathered. While the reserve potential in the dry natural gas formations of the Powder River Basin still exists, future drilling and development in this area will be affected by commodity prices and producers’ alternative prospects. The current commodity price environment has caused crude oil and natural gas producers to reduce drilling for crude oil and natural gas, which we expect will slow volume growth or reduce volumes of natural gas delivered to systems owned by our Powder River Basin equity method investments. A continued decline in volumes gathered in the coal-bed methane area of the Powder River Basin may reduce our ability to recover the carrying value of our equity investments in this area and could result in noncash charges to earnings. The net book value of our equity method investments in this dry natural gas area is $212.7 million , which includes $130.5 million of equity method goodwill.

RELATED-PARTY TRANSACTIONS

RELATED-PARTY TRANSACTIONS	6 Months Ended
	Jun. 30, 2015
Related Party Transactions [Abstract]
RELATED-PARTY TRANSACTIONS	J. RELATED-PARTY TRANSACTIONS Intersegment and affiliate sales are recorded on the same basis as sales to unaffiliated customers. Prior to April 1, 2014, our Natural Gas Gathering and Processing segment sold natural gas to ONEOK and its subsidiaries, and our Natural Gas Pipelines segment provided transportation and storage services to ONEOK and its subsidiaries. Additionally, our Natural Gas Gathering and Processing segment and Natural Gas Liquids segment purchased a portion of the natural gas used in their operations from ONEOK and its subsidiaries. On January 31, 2014, ONEOK completed the separation of its former natural gas distribution business into ONE Gas. ONE Gas was an affiliate prior to this separation. Commodity sales and services revenues in the Consolidated Statements of Income for the one month ended January 31, 2014, for transactions with ONE Gas prior to the separation are reflected as affiliate transactions. Transactions with ONE Gas that occurred after the separation are reflected as unaffiliated, third-party transactions. On March 31, 2014, ONEOK completed the wind down of ONEOK Energy Services Company, a subsidiary of ONEOK. For the first quarter 2014, we had transactions with ONEOK Energy Services Company, which are reflected as affiliate transactions. Under the Services Agreement with ONEOK and ONEOK Partners GP (the Services Agreement), our operations and the operations of ONEOK and its affiliates can combine or share certain common services in order to operate more efficiently and cost effectively. Under the Services Agreement, ONEOK provides to us similar services that it provides to its affiliates, including those services required to be provided pursuant to our Partnership Agreement. ONEOK Partners GP operates Guardian Pipeline, Viking Gas Transmission and Midwestern Gas Transmission according to each pipeline’s operating agreement. ONEOK Partners GP may purchase services from ONEOK and its affiliates pursuant to the terms of the Services Agreement. ONEOK Partners GP has no employees and utilizes the services of ONEOK to fulfill its operating obligations. ONEOK and its affiliates provide a variety of services to us under the Services Agreement, including cash management and financial services, employee benefits provided through ONEOK’s benefit plans, legal and administrative services, insurance and office space leased in ONEOK’s headquarters building and other field locations. Where costs are incurred specifically on behalf of one of our affiliates, the costs are billed directly to us by ONEOK. In other situations, the costs may be allocated to us through a variety of methods, depending upon the nature of the expense and activities. Beginning in the second quarter 2014, ONEOK allocates substantially all of its general overhead costs to us as a result of ONEOK’s separation of its natural gas distribution business and the wind down of its energy services business in the first quarter 2014. For the first quarter 2014, it is not practicable to determine what these general overhead costs would have been on a stand-alone basis. All costs directly charged or allocated to us are included in our Consolidated Statements of Income. The following table sets forth the transactions with related parties for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands of dollars ) Revenues $ — $ — $ — $ 53,526 Expenses Cost of sales and fuel $ — $ — $ — $ 10,835 Operating expenses 86,741 78,705 176,269 155,951 Total expenses $ 86,741 $ 78,705 $ 176,269 $ 166,786 ONEOK Partners GP made additional general partner contributions to us of approximately $5.7 million and $18.3 million during the six months ended June 30, 2015 and 2014 , respectively, to maintain its 2 percent general partner interest in connection with the issuances of common units. See Note F for additional information about cash distributions paid to ONEOK for its general partner and limited partner interests.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	K. COMMITMENTS AND CONTINGENCIES Environmental Matters - We are subject to multiple historical preservation, wildlife preservation and environmental laws and/or regulations that affect many aspects of our present and future operations. Regulated activities include, but are not limited to, those involving air emissions, storm water and wastewater discharges, handling and disposal of solid and hazardous wastes, wetlands preservation, hazardous materials transportation, and pipeline and facility construction. These laws and regulations require us to obtain and/or comply with a wide variety of environmental clearances, registrations, licenses, permits and other approvals. Failure to comply with these laws, regulations, licenses and permits may expose us to fines, penalties and/or interruptions in our operations that could be material to our results of operations. For example, if a leak or spill of hazardous substances or petroleum products occurs from pipelines or facilities that we own, operate or otherwise use, we could be held jointly and severally liable for all resulting liabilities, including response, investigation and cleanup costs, which could affect materially our results of operations and cash flows. In addition, emissions controls and/or other regulatory or permitting mandates under the Clean Air Act and other similar federal and state laws could require unexpected capital expenditures at our facilities. We cannot assure that existing environmental statutes and regulations will not be revised or that new regulations will not be adopted or become applicable to us. In June 2013, the Executive Office of the President of the United States (the President) issued the President’s Climate Action Plan, which includes, among other things, plans for further regulatory actions to reduce carbon emissions from various sources. On March 28, 2014, the President released the Climate Action Plan - Strategy to Reduce Methane Emissions (Methane Strategy) that lists a number of actions the federal agencies will undertake to continue to reduce above-ground methane emissions from several industries, including the oil and natural gas sectors. The proposed measures outlined in the Methane Strategy include, without limitation, the following: collaboration with the states to encourage emission reductions; standards to minimize natural gas venting and flaring on public lands; policy recommendations for reducing emissions from energy infrastructure to increase the performance of the nation’s energy transmission, storage and distribution systems; and continued efforts by PHMSA to require pipeline operators to take steps to eliminate leaks and prevent accidental methane releases and evaluate the progress of states in replacing cast-iron pipelines. The impact of any such regulatory actions on our facilities and operations is unknown. We continue to monitor these developments and the impact they may have on our businesses. Revised or additional statutes or regulations that result in increased compliance costs or additional operating restrictions could have a significant impact on our business, financial position, results of operations and cash flows. Our expenditures for environmental assessment, mitigation, remediation and compliance to date have not been significant in relation to our financial position, results of operations or cash flows, and our expenditures related to environmental matters have had no material effects on earnings or cash flows during the three and six months ended June 30, 2015 and 2014 . In April 2014, the EPA and the United States Army Corps of Engineers proposed a joint rule-making to redefine the definition of “Waters of the United States” under the Clean Water Act. The final rule was published on June 29, 2015, and becomes effective on August 28, 2015. The final rule is not expected to result in material impacts on our projects, facilities and operations. The EPA’s “Tailoring Rule” regulates GHG emissions at new or modified facilities that meet certain criteria. Affected facilities are required to review best available control technology (BACT), conduct air-quality analysis, impact analysis and public reviews with respect to such emissions. At current emission threshold levels, this rule has had a minimal impact on our existing facilities. In addition, on June 23, 2014, the Supreme Court of the United States (Supreme Court), in a case styled , Utility Air Regulatory Group v. EPA , 530 U.S. (2014), held that an industrial facility’s potential to emit GHG emissions alone cannot subject a facility to the permitting requirements for major stationary source provisions of the Clean Air Act. The decision invalidated the EPA’s current Triggering and Tailoring Rule for GHG Prevention of Significant Deterioration (PSD) and Title V requirements as applied to facilities considered major sources only for GHGs (referred to as Step 2 sources). However, the Supreme Court also ruled that to the extent a source pursues a capital project (new construction or expansion of existing facility), which otherwise subjects the source to major source PSD permitting for conventional criteria pollutants, the permitting authorities may impose BACT analysis and emission limits for GHGs from those sources. In April 2015, the United States Court of Appeals for the District of Columbia Circuit (D.C. Circuit), on remand from the Supreme Court, issued its further Order following the Supreme Court’s decision in Utility Air Regulatory Group v. EPA. The D.C. Circuit’s Order included the following: (1) it formally vacated EPA regulations implementing the Tailoring Rule to the extent that they require a stationary source to obtain a PSD or Title V permit based solely on the source’s GHG emissions; and (2) ordered the EPA to consider whether any further revisions to its regulations are appropriate in light of the Supreme Court’s decision. On April 30, 2015, the EPA issued a direct final rule to allow for the rescission of Clean Air Act PSD permits issued by the EPA or delegated state and local permitting authorities under Step 2 of the GHG Tailoring Rule. The direct final rule is effective on July 6, 2015, unless adverse comments were received by the EPA on or before June 8th. The EPA has not yet confirmed whether adverse comments were received on the direct final rule. Given this, we consider the direct final rule effective as of July 6, unless the EPA issues a notice of retraction. We do not expect the direct final rule to have a material impact on our existing operations or design decisions for new project applications. In July 2011, the EPA issued a proposed rule that would change the air emissions New Source Performance Standards, also known as NSPS, and Maximum Achievable Control Technology requirements applicable to the oil and natural gas industry, including natural gas production, processing, transmission and underground storage sectors. In April 2012, the EPA released the final rule, which includes new NSPS and air toxic standards for a variety of sources within natural gas processing plants, oil and natural gas production facilities and natural gas transmission stations. The rule also regulates emissions from the hydraulic fracturing of wells for the first time. The EPA’s final rule reflects significant changes from the proposal issued in 2011 and allows for more manageable compliance options. The NSPS final rule became effective in October 2012, but the dates for compliance vary and depend in part upon the type of affected facility and the date of construction, reconstruction or modification. Proposed amendments to the rule were published in March 2015. The EPA has indicated that further amendments will be issued in 2015, as part of the President’s Methane Strategy. We do not anticipate a material impact to our anticipated capital, operations and maintenance costs resulting from compliance with the current or pending regulations. However, the EPA may issue additional responses, amendments and/or policy guidance on the final rule, which could alter our present expectations. Generally, the NSPS rule will require expenditures for updated emissions controls, monitoring and record-keeping requirements at affected facilities in the crude oil and natural gas industry. We do not expect these expenditures will have a material impact on our results of operations, financial position or cash flows. Pipeline Safety - We are subject to PHMSA regulations, including pipeline asset integrity-management regulations. The Pipeline Safety Improvement Act of 2002 requires pipeline companies operating high-pressure pipelines to perform integrity assessments on pipeline segments that pass through densely populated areas or near specifically designated high-consequence areas. In January 2012, The Pipeline Safety, Regulatory Certainty and Job Creation Act of 2011 was signed into law. The law increased maximum penalties for violating federal pipeline safety regulations and directs the DOT and Secretary of Transportation to conduct further review or studies on issues that may or may not be material to us. These issues include, but are not limited to, the following: • an evaluation on whether hazardous natural gas liquids and natural gas pipeline integrity-management requirements should be expanded beyond current high-consequence areas; • a review of all natural gas and hazardous natural gas liquids gathering pipeline exemptions; • a verification of records for pipelines in Class 3 and 4 locations and high-consequence areas to confirm maximum allowable operating pressures; and • a requirement to test previously untested pipelines operating above 30 percent yield strength in high-consequence areas. The potential capital and operating expenditures related to this legislation, the associated regulations or other new pipeline safety regulations are unknown. 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.

SEGMENTS

SEGMENTS	6 Months Ended
	Jun. 30, 2015
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
SEGMENTS	L. SEGMENTS Segment Descriptions - Our operations are divided into three reportable business segments, as follows: • our Natural Gas Gathering and Processing segment gathers, treats and processes natural gas; • our Natural Gas Liquids segment gathers, treats, fractionates and transports NGLs and stores, markets and distributes NGL products; and • our Natural Gas Pipelines segment operates regulated interstate and intrastate natural gas transmission pipelines and natural gas storage facilities. Accounting Policies - We evaluate performance based principally on each segment’s operating income and equity earnings. The accounting policies of the segments are described in Note A of the Notes to Consolidated Financial Statements in our Annual Report. Intersegment and affiliate sales are recorded on the same basis as sales to unaffiliated customers. Net margin is comprised of total revenues less cost of sales and fuel. Cost of sales and fuel includes commodity purchases, fuel, storage and transportation costs. As a result of ONEOK’s separation of its natural gas distribution business into a stand-alone publicly traded company, ONE Gas, on January 31, 2014, transactions with ONE Gas subsequent to the separation are reflected as sales to unaffiliated customers. Customers - The primary customers for our Natural Gas Gathering and Processing segment are major and independent crude oil and natural gas production companies. Our Natural Gas Liquids segment’s customers are primarily NGL and natural gas gathering and processing companies, major and independent crude oil and natural gas production companies, propane distributors, ethanol producers and petrochemical, refining and NGL marketing companies. Our Natural Gas Pipelines segment’s customers include natural gas distribution, electric-generation, natural gas marketing, industrial and major and independent crude oil and natural gas production companies. For the three and six months ended June 30, 2015 , we had one customer, BP p.l.c., from which we received $224.6 million and $409.5 million , respectively, in total revenues from all of our operating segments, or approximately 11 percent and 10 percent of our consolidated revenues, respectively. For the three and six months ended June 30, 2014 , we had no single customer from which we received 10 percent or more of our consolidated revenues. Operating Segment Information - The following tables set forth certain selected financial information for our operating segments for the periods indicated: Three Months Ended June 30, 2015 Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Other and Eliminations Total ( Thousands of dollars ) Sales to unaffiliated customers $ 279,498 $ 1,769,580 $ 78,429 $ — $ 2,127,507 Intersegment revenues 180,564 79,295 1,683 (261,542 ) — Total revenues $ 460,062 $ 1,848,875 $ 80,112 $ (261,542 ) $ 2,127,507 Net margin $ 137,135 $ 313,383 $ 74,107 $ (211 ) $ 524,414 Operating costs 63,550 77,410 25,240 412 166,612 Depreciation and amortization 35,952 39,433 10,814 — 86,199 Gain (loss) on sale of assets 195 (73 ) — — 122 Operating income $ 37,828 $ 196,467 $ 38,053 $ (623 ) $ 271,725 Equity in net earnings from investments $ 4,922 $ 9,693 $ 15,425 $ — $ 30,040 Capital expenditures $ 205,434 $ 59,087 $ 15,613 $ 5,226 $ 285,360 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $227.5 million , of which $186.4 million was related to sales within the segment, net margin of $128.5 million and operating income of $73.6 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $64.1 million , net margin of $57.1 million and operating income of $25.7 million . Three Months Ended June 30, 2014 Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Other and Eliminations Total ( Thousands of dollars ) Sales to unaffiliated customers $ 374,112 $ 2,612,336 $ 79,287 $ — $ 3,065,735 Intersegment revenues 349,253 52,974 2,698 (404,925 ) — Total revenues $ 723,365 $ 2,665,310 $ 81,985 $ (404,925 ) $ 3,065,735 Net margin $ 154,970 $ 266,145 $ 75,471 $ (2,253 ) $ 494,333 Operating costs 59,386 76,081 27,287 (2,109 ) 160,645 Depreciation and amortization 29,443 31,109 10,895 — 71,447 Gain (loss) on sale of assets (28 ) 11 — 1 (16 ) Operating income $ 66,113 $ 158,966 $ 37,289 $ (143 ) $ 262,225 Equity in net earnings from investments $ 5,099 $ 4,459 $ 15,877 $ — $ 25,435 Capital expenditures $ 168,208 $ 210,676 $ 8,710 $ 1,819 $ 389,413 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $153.3 million , of which $135.3 million was related to sales within the segment, net margin of $84.4 million and operating income of $34.5 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $68.3 million , net margin of $59.5 million and operating income of $26.1 million . Six Months Ended June 30, 2015 Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Other and Eliminations Total ( Thousands of dollars ) Sales to unaffiliated customers $ 567,514 $ 3,204,393 $ 160,359 $ — $ 3,932,266 Intersegment revenues 348,171 140,574 3,302 (492,047 ) — Total revenues $ 915,685 $ 3,344,967 $ 163,661 $ (492,047 ) $ 3,932,266 Net margin $ 261,827 $ 580,610 $ 143,230 $ (358 ) $ 985,309 Operating costs 132,760 159,656 52,482 (127 ) 344,771 Depreciation and amortization 71,749 78,727 21,570 — 172,046 Gain (loss) on sale of assets 196 (81 ) 1 — 116 Operating income $ 57,514 $ 342,146 $ 69,179 $ (231 ) $ 468,608 Equity in net earnings from investments $ 9,161 $ 16,673 $ 35,127 $ — $ 60,961 Investments in unconsolidated affiliates $ 252,468 $ 485,381 $ 408,558 $ — $ 1,146,407 Total assets $ 5,007,456 $ 8,139,588 $ 1,841,321 $ 8,288 $ 14,996,653 Noncontrolling interests in consolidated subsidiaries $ 4,065 $ 162,494 $ — $ — $ 166,559 Capital expenditures $ 460,735 $ 132,553 $ 25,205 $ 9,903 $ 628,396 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $437.3 million , of which $351.7 million was related to sales within the segment, net margin of $252.6 million and operating income of $138.5 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $133.4 million , net margin of $118.0 million and operating income of $53.1 million . Six Months Ended June 30, 2014 Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Other and Eliminations Total ( Thousands of dollars ) Sales to unaffiliated customers $ 721,128 $ 5,282,991 $ 170,393 $ — $ 6,174,512 Sales to affiliated customers 41,214 — 12,312 — 53,526 Intersegment revenues 723,148 94,131 4,073 (821,352 ) — Total revenues $ 1,485,490 $ 5,377,122 $ 186,778 $ (821,352 ) $ 6,228,038 Net margin $ 308,524 $ 535,123 $ 168,960 $ (8,640 ) $ 1,003,967 Operating costs 124,210 141,183 54,749 (9,314 ) 310,828 Depreciation and amortization 58,285 58,187 21,710 — 138,182 Gain (loss) on sale of assets (47 ) (37 ) (83 ) 166 (1 ) Operating income $ 125,982 $ 335,716 $ 92,418 $ 840 $ 554,956 Equity in net earnings from investments $ 10,585 $ 9,223 $ 39,286 $ — $ 59,094 Investments in unconsolidated affiliates $ 329,726 $ 485,960 $ 396,722 $ — $ 1,212,408 Total assets $ 4,276,593 $ 7,363,417 $ 1,852,901 $ 255,604 $ 13,748,515 Noncontrolling interests in consolidated subsidiaries $ 4,493 $ — $ — $ 15 $ 4,508 Capital expenditures $ 291,099 $ 483,739 $ 15,337 $ 2,239 $ 792,414 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $289.1 million , of which $246.9 million was related to sales within the segment, net margin of $169.1 million and operating income of $79.6 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $149.6 million , net margin of $128.1 million and operating income of $61.2 million .

SUPPLEMENTAL CONDENSED CONSOLID

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION	6 Months Ended
	Jun. 30, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Supplemental Condensed Consolidating Financial Information	M. SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION We have no significant assets or operations other than our investment in our 100 percent-owned subsidiary, the Intermediate Partnership. The Intermediate Partnership holds all our partnership interests and equity in our subsidiaries, as well as a 50 percent interest in Northern Border Pipeline. The Intermediate Partnership guarantees our senior notes and borrowings, if any, under the Partnership Credit Agreement. The Intermediate Partnership’s guarantees of our senior notes and of any borrowings under the Partnership Credit Agreement are full and unconditional, subject to certain customary automatic release provisions. For purposes of the following footnote: • we are referred to as “Parent”; • the Intermediate Partnership is referred to as “Guarantor Subsidiary”; and • the “Non-Guarantor Subsidiaries” are all subsidiaries other than the Guarantor Subsidiary. The following unaudited supplemental condensed consolidating financial information is presented on an equity-method basis reflecting the Parent’s separate accounts, the Guarantor Subsidiary’s separate accounts, the combined accounts of the Non-Guarantor Subsidiaries, the combined consolidating adjustments and eliminations, and the Parent’s consolidated amounts for the periods indicated. Condensed Consolidating Statements of Income Three Months Ended June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ 1,722.3 $ — $ 1,722.3 Services — — 405.3 — 405.3 Total revenues — — 2,127.6 — 2,127.6 Cost of sales and fuel — — 1,603.1 — 1,603.1 Net margin — — 524.5 — 524.5 Operating expenses Operations and maintenance — — 143.1 — 143.1 Depreciation and amortization — — 86.2 — 86.2 General taxes — — 23.5 — 23.5 Total operating expenses — — 252.8 — 252.8 Gain (loss) on sale of assets — — 0.1 — 0.1 Operating income — — 271.8 — 271.8 Equity in net earnings from investments 209.8 209.8 14.6 (404.2 ) 30.0 Allowance for equity funds used during construction — — 0.7 — 0.7 Other income (expense), net 95.3 95.3 (1.9 ) (190.6 ) (1.9 ) Interest expense, net (95.3 ) (95.3 ) (86.5 ) 190.6 (86.5 ) Income before income taxes 209.8 209.8 198.7 (404.2 ) 214.1 Income taxes — — (2.5 ) — (2.5 ) Net income 209.8 209.8 196.2 (404.2 ) 211.6 Less: Net income attributable to noncontrolling interests — — 1.8 — 1.8 Net income attributable to ONEOK Partners, L.P. $ 209.8 $ 209.8 $ 194.4 $ (404.2 ) $ 209.8 Three Months Ended June 30, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ 2,715.1 $ — $ 2,715.1 Services — — 350.6 — 350.6 Total revenues — — 3,065.7 — 3,065.7 Cost of sales and fuel — — 2,571.4 — 2,571.4 Net margin — — 494.3 — 494.3 Operating expenses Operations and maintenance — — 142.7 — 142.7 Depreciation and amortization — — 71.4 — 71.4 General taxes — — 18.0 — 18.0 Total operating expenses — — 232.1 — 232.1 Gain (loss) on sale of assets — — — — — Operating income — — 262.2 — 262.2 Equity in net earnings from investments 214.4 214.4 9.6 (413.0 ) 25.4 Allowance for equity funds used during construction — — 1.3 — 1.3 Other income (expense), net 83.1 83.1 1.8 (166.2 ) 1.8 Interest expense, net (83.1 ) (83.1 ) (73.0 ) 166.2 (73.0 ) Income before income taxes 214.4 214.4 201.9 (413.0 ) 217.7 Income taxes — — (3.2 ) — (3.2 ) Net income 214.4 214.4 198.7 (413.0 ) 214.5 Less: Net income attributable to noncontrolling interests — — 0.1 — 0.1 Net income attributable to ONEOK Partners, L.P. $ 214.4 $ 214.4 $ 198.6 $ (413.0 ) $ 214.4 Six Months Ended June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ 3,158.0 $ — $ 3,158.0 Services — — 774.3 — 774.3 Total revenues — — 3,932.3 — 3,932.3 Cost of sales and fuel — — 2,947.0 — 2,947.0 Net margin — — 985.3 — 985.3 Operating expenses Operations and maintenance — — 298.3 — 298.3 Depreciation and amortization — — 172.0 — 172.0 General taxes — — 46.5 — 46.5 Total operating expenses — — 516.8 — 516.8 Gain (loss) on sale of assets — — 0.1 — 0.1 Operating income — — 468.6 — 468.6 Equity in net earnings from investments 355.4 355.4 25.8 (675.6 ) 61.0 Allowance for equity funds used during construction — — 1.5 — 1.5 Other income (expense), net 182.1 182.1 — (364.2 ) — Interest expense, net (182.1 ) (182.1 ) (167.2 ) 364.2 (167.2 ) Income before income taxes 355.4 355.4 328.7 (675.6 ) 363.9 Income taxes — — (5.3 ) — (5.3 ) Net income 355.4 355.4 323.4 (675.6 ) 358.6 Less: Net income attributable to noncontrolling interests — — 3.2 — 3.2 Net income attributable to ONEOK Partners, L.P. $ 355.4 $ 355.4 $ 320.2 $ (675.6 ) $ 355.4 Six Months Ended June 30, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ 5,521.8 $ — $ 5,521.8 Services — — 706.2 — 706.2 Total revenues — — 6,228.0 — 6,228.0 Cost of sales and fuel — — 5,224.0 — 5,224.0 Net margin — — 1,004.0 — 1,004.0 Operating expenses Operations and maintenance — — 273.2 — 273.2 Depreciation and amortization — — 138.2 — 138.2 General taxes — — 37.6 — 37.6 Total operating expenses — — 449.0 — 449.0 Gain (loss) on sale of assets — — — — — Operating income — — 555.0 — 555.0 Equity in net earnings from investments 479.8 479.8 19.8 (920.3 ) 59.1 Allowance for equity funds used during construction — — 12.2 — 12.2 Other income (expense), net 165.8 165.8 2.4 (331.6 ) 2.4 Interest expense, net (165.8 ) (165.8 ) (141.3 ) 331.6 (141.3 ) Income before income taxes 479.8 479.8 448.1 (920.3 ) 487.4 Income taxes — — (7.4 ) — (7.4 ) Net income 479.8 479.8 440.7 (920.3 ) 480.0 Less: Net income attributable to noncontrolling interests — — 0.2 — 0.2 Net income attributable to ONEOK Partners, L.P. $ 479.8 $ 479.8 $ 440.5 $ (920.3 ) $ 479.8 Condensed Consolidating Statements of Comprehensive Income Three Months Ended June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 209.8 $ 209.8 $ 196.2 $ (404.2 ) $ 211.6 Other comprehensive income (loss) Unrealized gains (losses) on derivatives 18.0 1.1 1.1 (2.2 ) 18.0 Realized (gains) losses on derivatives recognized in net income (13.4 ) (17.1 ) (17.1 ) 34.2 (13.4 ) Total other comprehensive income (loss) 4.6 (16.0 ) (16.0 ) 32.0 4.6 Comprehensive income 214.4 193.8 180.2 (372.2 ) 216.2 Less: Comprehensive income attributable to noncontrolling interests — — 1.8 — 1.8 Comprehensive income attributable to ONEOK Partners, L.P. $ 214.4 $ 193.8 $ 178.4 $ (372.2 ) $ 214.4 Three Months Ended June 30, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 214.4 $ 214.4 $ 198.7 $ (413.0 ) $ 214.5 Other comprehensive income (loss) Unrealized gains (losses) on derivatives (32.5 ) (6.1 ) (6.1 ) 12.2 (32.5 ) Realized (gains) losses on derivatives recognized in net income 7.8 5.2 5.2 (10.4 ) 7.8 Total other comprehensive income (loss) (24.7 ) (0.9 ) (0.9 ) 1.8 (24.7 ) Comprehensive income 189.7 213.5 197.8 (411.2 ) 189.8 Less: Comprehensive income attributable to noncontrolling interests — — 0.1 — 0.1 Comprehensive income attributable to ONEOK Partners, L.P. $ 189.7 $ 213.5 $ 197.7 $ (411.2 ) $ 189.7 Six Months Ended June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 355.4 $ 355.4 $ 323.4 $ (675.6 ) $ 358.6 Other comprehensive income (loss) Unrealized gains (losses) on derivatives 5.4 11.1 11.1 (22.2 ) 5.4 Realized (gains) losses on derivatives recognized in net income (24.7 ) (31.3 ) (31.3 ) 62.6 (24.7 ) Total other comprehensive income (loss) (19.3 ) (20.2 ) (20.2 ) 40.4 (19.3 ) Comprehensive income 336.1 335.2 303.2 (635.2 ) 339.3 Less: Comprehensive income attributable to noncontrolling interests — — 3.2 — 3.2 Comprehensive income attributable to ONEOK Partners, L.P. $ 336.1 $ 335.2 $ 300.0 $ (635.2 ) $ 336.1 Six Months Ended June 30, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 479.8 $ 479.8 $ 440.7 $ (920.3 ) $ 480.0 Other comprehensive income (loss) Unrealized gains (losses) on derivatives (89.0 ) (41.9 ) (41.9 ) 83.8 (89.0 ) Realized (gains) losses on derivatives recognized in net income 36.9 31.6 31.6 (63.2 ) 36.9 Total other comprehensive income (loss) (52.1 ) (10.3 ) (10.3 ) 20.6 (52.1 ) Comprehensive income 427.7 469.5 430.4 (899.7 ) 427.9 Less: Comprehensive income attributable to noncontrolling interests — — 0.2 — 0.2 Comprehensive income attributable to ONEOK Partners, L.P. $ 427.7 $ 469.5 $ 430.2 $ (899.7 ) $ 427.7 Condensed Consolidating Balance Sheets June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total Assets ( Millions of dollars ) Current assets Cash and cash equivalents $ — $ 53.1 $ — $ — $ 53.1 Accounts receivable, net — — 683.7 — 683.7 Affiliate receivables — — 1.8 — 1.8 Natural gas and natural gas liquids in storage — — 150.1 — 150.1 Commodity imbalances — — 31.2 — 31.2 Materials and supplies — — 60.5 — 60.5 Other current assets 0.7 — 56.2 — 56.9 Total current assets 0.7 53.1 983.5 — 1,037.3 Property, plant and equipment Property, plant and equipment — — 13,949.9 — 13,949.9 Accumulated depreciation and amortization — — 1,995.9 — 1,995.9 Net property, plant and equipment — — 11,954.0 — 11,954.0 Investments and other assets Investments in unconsolidated affiliates 3,989.8 5,756.1 772.2 (9,371.7 ) 1,146.4 Intercompany notes receivable 9,696.4 7,877.0 — (17,573.4 ) — Goodwill and intangible assets — — 830.8 — 830.8 Other assets 7.0 — 21.2 — 28.2 Total investments and other assets 13,693.2 13,633.1 1,624.2 (26,945.1 ) 2,005.4 Total assets $ 13,693.9 $ 13,686.2 $ 14,561.7 $ (26,945.1 ) $ 14,996.7 Liabilities and equity Current liabilities Current maturities of long-term debt $ 650.0 $ — $ 7.7 $ — $ 657.7 Notes payable 870.5 — — — 870.5 Accounts payable — — 687.3 — 687.3 Affiliate payables — — 28.3 — 28.3 Commodity imbalances — — 91.6 — 91.6 Accrued interest 102.2 — — — 102.2 Other current liabilities — — 127.0 — 127.0 Total current liabilities 1,622.7 — 941.9 — 2,564.6 Intercompany debt — 9,696.4 7,877.0 (17,573.4 ) — Long-term debt, excluding current maturities 6,098.0 — 48.0 — 6,146.0 Deferred credits and other liabilities — — 146.3 — 146.3 Commitments and contingencies Equity Equity excluding noncontrolling interests in consolidated subsidiaries 5,973.2 3,989.8 5,381.9 (9,371.7 ) 5,973.2 Noncontrolling interests in consolidated subsidiaries — — 166.6 — 166.6 Total equity 5,973.2 3,989.8 5,548.5 (9,371.7 ) 6,139.8 Total liabilities and equity $ 13,693.9 $ 13,686.2 $ 14,561.7 $ (26,945.1 ) $ 14,996.7 December 31, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total Assets ( Millions of dollars ) Current assets Cash and cash equivalents $ — $ 42.5 $ — $ — $ 42.5 Accounts receivable, net — — 735.8 — 735.8 Affiliate receivables — — 8.6 — 8.6 Natural gas and natural gas liquids in storage — — 134.1 — 134.1 Commodity imbalances — — 64.8 — 64.8 Materials and supplies — — 55.8 — 55.8 Other current assets 1.9 — 42.5 — 44.4 Total current assets 1.9 42.5 1,041.6 — 1,086.0 Property, plant and equipment Property, plant and equipment — — 13,377.6 — 13,377.6 Accumulated depreciation and amortization — — 1,842.1 — 1,842.1 Net property, plant and equipment — — 11,535.5 — 11,535.5 Investments and other assets Investments in unconsolidated affiliates 4,248.0 5,469.8 746.1 (9,331.3 ) 1,132.6 Intercompany notes receivable 8,843.3 7,579.0 — (16,422.3 ) — Goodwill and intangible assets — — 822.4 — 822.4 Other assets 2.1 — 21.8 — 23.9 Total investments and other assets 13,093.4 13,048.8 1,590.3 (25,753.6 ) 1,978.9 Total assets $ 13,095.3 $ 13,091.3 $ 14,167.4 $ (25,753.6 ) $ 14,600.4 Liabilities and equity Current liabilities Current maturities of long-term debt $ — $ — $ 7.7 $ — $ 7.7 Notes payable 1,055.3 — — — 1,055.3 Accounts payable — — 874.7 — 874.7 Affiliate payables — — 36.1 — 36.1 Commodity imbalances — — 104.7 — 104.7 Accrued interest 92.0 — — — 92.0 Other current liabilities 44.8 — 120.8 — 165.6 Total current liabilities 1,192.1 — 1,144.0 — 2,336.1 Intercompany debt — 8,843.3 7,579.0 (16,422.3 ) — Long-term debt, excluding current maturities 5,952.4 — 51.9 — 6,004.3 Deferred credits and other liabilities — — 141.3 — 141.3 Commitments and contingencies Equity Equity excluding noncontrolling interests in consolidated subsidiaries 5,950.8 4,248.0 5,083.3 (9,331.3 ) 5,950.8 Noncontrolling interests in consolidated subsidiaries — — 167.9 — 167.9 Total equity 5,950.8 4,248.0 5,251.2 (9,331.3 ) 6,118.7 Total liabilities and equity $ 13,095.3 $ 13,091.3 $ 14,167.4 $ (25,753.6 ) $ 14,600.4 Condensed Consolidating Statements of Cash Flows Six Months Ended June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Operating activities Cash provided by operating activities $ 550.2 $ 35.0 $ 388.6 $ (593.5 ) $ 380.3 Investing activities Capital expenditures (less allowance for equity funds used during construction) — — (628.4 ) — (628.4 ) Contributions to unconsolidated affiliates — — (33.2 ) — (33.2 ) Distributions received from unconsolidated affiliates in excess of cumulative earnings — 12.4 6.4 — 18.8 Proceeds from sale of assets — — 0.7 — 0.7 Other — — (12.6 ) — (12.6 ) Cash provided by (used in) investing activities — 12.4 (667.1 ) — (654.7 ) Financing activities Cash distributions: General and limited partners (593.5 ) (593.5 ) — 593.5 (593.5 ) Noncontrolling interests — — (4.7 ) — (4.7 ) Borrowing (repayment) of notes payable, net (184.8 ) — — — (184.8 ) Issuance of long-term debt, net of discounts 798.9 — — — 798.9 Debt financing costs (7.9 ) — — — (7.9 ) Intercompany borrowings (advances), net (843.7 ) 556.7 287.0 — — Repayment of long-term debt — — (3.8 ) — (3.8 ) Issuance of common units, net of issuance costs 275.1 — — — 275.1 Contribution from general partner 5.7 — — — 5.7 Cash provided by (used in) financing activities (550.2 ) (36.8 ) 278.5 593.5 285.0 Change in cash and cash equivalents — 10.6 — — 10.6 Cash and cash equivalents at beginning of period — 42.5 — — 42.5 Cash and cash equivalents at end of period $ — $ 53.1 $ — $ — $ 53.1 Six Months Ended June 30, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Operating activities Cash provided by operating activities $ 505.3 $ 39.3 $ 482.6 $ (493.1 ) $ 534.1 Investing activities Capital expenditures (less allowance for equity funds used during construction) — — (792.4 ) — (792.4 ) Cash paid for acquisitions — — (14.0 ) — (14.0 ) Contributions to unconsolidated affiliates — — (1.1 ) — (1.1 ) Distributions received from unconsolidated affiliates in excess of cumulative earnings — 8.1 8.4 — 16.5 Proceeds from sale of assets — — 0.3 — 0.3 Cash provided by (used in) investing activities — 8.1 (798.8 ) — (790.7 ) Financing activities Cash distributions: General and limited partners (493.1 ) (493.1 ) — 493.1 (493.1 ) Noncontrolling interests — — (0.2 ) — (0.2 ) Borrowing (repayment) of notes payable, net — — — — — Intercompany borrowings (advances), net (909.4 ) 589.2 320.2 — — Repayment of long-term debt — — (3.8 ) — (3.8 ) Issuance of common units, net of issuance costs 878.8 — — — 878.8 Contribution from general partner 18.4 — — — 18.4 Cash provided by (used in) financing activities (505.3 ) 96.1 316.2 493.1 400.1 Change in cash and cash equivalents — 143.5 — — 143.5 Cash and cash equivalents at beginning of period — 134.5 — — 134.5 Cash and cash equivalents at end of period $ — $ 278.0 $ — $ — $ 278.0

SUMMARY OF SIGNIFICANT ACCOUN22

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Line Items]
Basis of Accounting, Policy [Policy Text Block]	Our accompanying unaudited consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC. These statements have been prepared in accordance with GAAP and reflect all adjustments that, in our opinion, are necessary for a fair presentation of the results for the interim periods presented. All such adjustments are of a normal recurring nature. The 2014 year-end consolidated balance sheet data was derived from our audited financial statements but does not include all disclosures required by GAAP. These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements in our Annual Report. Our significant accounting policies are consistent with those disclosed in Note A of the Notes to Consolidated Financial Statements in our Annual Report.
Business Combinations Policy [Policy Text Block]	We accounted for this acquisition as a business combination that, among other things, requires assets acquired and liabilities assumed to be measured at their acquisition-date fair values.
Accounting Standards Update 2015-03 [Member]
Accounting Policies [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In March 2015, the FASB issued ASU 2015-03, “Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs,” which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. This guidance is effective for public companies for fiscal years beginning after December 15, 2015, with early adoption permitted. We elected to adopt this guidance early beginning in the second quarter 2015. Retrospective adjustment of prior periods presented is required. Therefore, the December 31, 2014, balance sheet has been recast to reclassify $34.1 million of debt issuance costs from other assets to long-term debt. The impact of adopting this guidance was not material.
Accounting Standards Update 2014-08 [Member]
Accounting Policies [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In April 2014, the FASB issued ASU 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity,” which alters the definition of a discontinued operation to include only asset disposals that represent a strategic shift with a major effect on an entity’s operations and financial results. The amendment also requires more extensive disclosures about a discontinued operation’s assets, liabilities, income, expenses and cash flows. This guidance will be effective for interim and annual periods for all assets that are disposed of or classified as being held for sale in fiscal years that begin on or after December 15, 2014. We adopted this guidance beginning in the first quarter 2015, and it could impact us in the future if we dispose of any individually significant components.
Accounting Standards Update 2015-05 [Member]
Accounting Policies [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In April 2015, the FASB issued ASU 2015-05, “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement,” which clarifies whether a cloud computing arrangement includes a software license. If it does, the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses; if not, the customer should not account for the arrangement as a service contract. This guidance is effective for public companies for fiscal years beginning after December 15, 2015. Early adoption is permitted. We expect to adopt this guidance in the first quarter 2016, and we do not expect it to materially impact us.
Accounting Standards Update 2015-02 [Member]
Accounting Policies [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In February 2015, the FASB issued ASU 2015-02, “Consolidation (Topic 810): Amendments to the Consolidation Analysis,” which eliminates the presumption that a general partner should consolidate a limited partnership. It also modifies the evaluation of whether limited partnerships are variable interest entities or voting interest entities and adds requirements that limited partnerships must meet to qualify as voting interest entities. This guidance is effective for public companies for fiscal years beginning after December 15, 2015. We expect to adopt this guidance in the first quarter 2016, and we are evaluating the impact on us.
Accounting Standards Update 2014-15 [Member]
Accounting Policies [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In August 2014, the FASB issued ASU 2014-15, “Going Concern,” which provides guidance on determining when and how to disclose going-concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if conditions or events raise substantial doubt about the entity’s ability to continue as a going concern. The standard applies to all entities and is effective for annual periods ending after December 15, 2016, and interim periods thereafter, with early adoption permitted. We expect to adopt this guidance beginning in the first quarter 2016, and we do not expect it to materially impact us.
Accounting Standards Update 2014-09 [Member]
Accounting Policies [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers,” which outlines the principles an entity must apply to measure and recognize revenue for entities that enter into contracts to provide goods or services to their customers. The core principle is that an entity should recognize revenue at an amount that reflects the consideration to which the entity expects to be entitled in exchange for transferring goods or services to a customer. The amendment also requires more extensive disaggregated revenue disclosures in interim and annual financial statements. In July 2015, the FASB announced it has deferred the effective date by one year. This update is now effective for interim and annual periods that begin after December 15, 2017, with either retrospective application for all periods presented or retrospective application with a cumulative effect adjustment. We expect to adopt this guidance beginning in the first quarter 2018, and we are evaluating the impact on us.

FAIR VALUE MEASUREMENTS FAIR VA

FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS (Policies)	6 Months Ended
	Jun. 30, 2015
Fair Value Accounting Policy [Abstract]
Fair Value of Financial Instruments, Policy [Policy Text Block]	Determining Fair Value - We define fair value as the price that would be received from the sale of an asset or the transfer of a liability in an orderly transaction between market participants at the measurement date. We use market and income approaches to determine the fair value of our assets and liabilities and consider the markets in which the transactions are executed. We measure the fair value of a group of financial assets and liabilities consistent with how a market participant would price the net risk exposure at the measurement date. While many of the contracts in our portfolio are executed in liquid markets where price transparency exists, some contracts are executed in markets for which market prices may exist, but the market may be relatively inactive. This results in limited price transparency that requires management’s judgment and assumptions to estimate fair values. For certain transactions, we utilize modeling techniques using NYMEX-settled pricing data and implied forward LIBOR curves. Inputs into our fair value estimates include commodity-exchange prices, over-the-counter quotes, historical correlations of pricing data, data obtained from third-party pricing services and LIBOR and other liquid money-market instrument rates. We validate our valuation inputs with third-party information and settlement prices from other sources, where available. In addition, as prescribed by the income approach, we compute the fair value of our derivative portfolio by discounting the projected future cash flows from our derivative assets and liabilities to present value using interest-rate yields to calculate present-value discount factors derived from LIBOR, Eurodollar futures and interest-rate swaps. We also take into consideration the potential impact on market prices of liquidating positions in an orderly manner over a reasonable period of time under current market conditions. We consider current market data in evaluating counterparties’, as well as our own, nonperformance risk, net of collateral, by using specific and sector bond yields and monitoring the credit default swap markets. Although we use our best estimates to determine the fair value of the derivative contracts we have executed, the ultimate market prices realized could differ from our estimates, and the differences could be material. The fair value of our forward-starting interest-rate swaps are determined using financial models that incorporate the implied forward LIBOR yield curve for the same period as the future interest swap settlements. Fair Value Hierarchy - At each balance sheet date, we utilize a fair value hierarchy to classify fair value amounts recognized or disclosed in our financial statements based on the observability of inputs used to estimate such fair value. The levels of the hierarchy are described below: • Level 1 - fair value measurements are based on unadjusted quoted prices for identical securities in active markets, including NYMEX-settled prices. These balances are comprised predominantly of exchange-traded derivative contracts for natural gas and crude oil. • Level 2 - fair value measurements are based on significant observable pricing inputs, such as NYMEX-settled prices for natural gas and crude oil, and financial models that utilize implied forward LIBOR yield curves for interest-rate swaps. • Level 3 - fair value measurements are based on inputs that may include one or more unobservable inputs, including natural gas basis and NGL price curves that incorporate observable and unobservable market data from broker quotes, third-party pricing services , market volatilities derived from the most recent NYMEX close spot prices and forward LIBOR curves, and adjustments for the credit risk of our counterparties. We corroborate the data on which our fair value estimates are based using our market knowledge of recent transactions, analysis of historical correlations and validation with independent broker quotes. These balances categorized as Level 3 are comprised of derivatives for natural gas and NGLs. We do not believe that our Level 3 fair value estimates have a material impact on our results of operations, as the majority of our derivatives are accounted for as hedges for which ineffectiveness has not been material. 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.

RISK MANAGEMENT AND HEDGING A24

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES (Policies)	6 Months Ended
	Jun. 30, 2015
RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES [Abstract]
Accounting treatment for derivative instruments	We record all derivative instruments at fair value, with the exception of normal purchases and normal sales transactions that are expected to result in physical delivery. Commodity price and interest-rate volatility may have a significant impact on the fair value of derivative instruments as of a given date. The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and, if so, the reason for holding it. The table below summarizes the various ways in which we account for our derivative instruments and the impact on our consolidated financial statements: Recognition and Measurement Accounting Treatment Balance Sheet Income Statement Normal purchases and normal sales - Fair value not recorded - Change in fair value not recognized in earnings Mark-to-market - Recorded at fair value - Change in fair value recognized in earnings Cash flow hedge - Recorded at fair value - Ineffective portion of the gain or loss on the derivative instrument is recognized in earnings - Effective portion of the gain or loss on the derivative instrument is reported initially as a component of accumulated other comprehensive income (loss) - Effective portion of the gain or loss on the derivative instrument is reclassified out of accumulated other comprehensive income (loss) into earnings when the forecasted transaction affects earnings Fair value hedge - Recorded at fair value - The gain or loss on the derivative instrument is recognized in earnings - Change in fair value of the hedged item is recorded as an adjustment to book value - Change in fair value of the hedged item is recognized in earnings To reduce our exposure to fluctuations in natural gas, NGLs and condensate prices, we periodically enter into futures, forward purchases and sales, options or swap transactions in order to hedge anticipated purchases and sales of natural gas, NGLs and condensate. Interest-rate swaps are used from time to time to manage interest-rate risk. Under certain conditions, we designate our derivative instruments as a hedge of exposure to changes in fair values or cash flows. We formally document all relationships between hedging instruments and hedged items, as well as risk-management objectives and strategies for undertaking various hedge transactions, and methods for assessing and testing correlation and hedge ineffectiveness. We specifically identify the forecasted transaction that has been designated as the hedged item in a cash flow hedge relationship. We assess the effectiveness of hedging relationships quarterly by performing an effectiveness analysis on our fair value and cash flow hedging relationships to determine whether the hedge relationships are highly effective on a retrospective and prospective basis. We also document our normal purchases and normal sales transactions that we expect to result in physical delivery and that we elect to exempt from derivative accounting treatment. The realized revenues and purchase costs of our derivative instruments not considered held for trading purposes and derivatives that qualify as normal purchases or normal sales that are expected to result in physical delivery are reported on a gross basis. Cash flows from futures, forwards and swaps that are accounted for as hedges are included in the same category as the cash flows from the related hedged items in our Consolidated Statements of Cash Flows.

EQUITY (Policies)

EQUITY (Policies)	6 Months Ended
	Jun. 30, 2015
EQUITY (Policies)
Partnership agreement	Partnership Agreement - Available cash, as defined in our Partnership Agreement, generally will be distributed to our general partner and limited partners according to their partnership percentages of 2 percent and 98 percent, respectively. Our general partner’s percentage interest in quarterly distributions is increased after certain specified target levels are met during the quarter. Under the incentive distribution provisions, as set forth in our Partnership Agreement, our general partner receives: • 15 percent of amounts distributed in excess of $0.3025 per unit; • 25 percent of amounts distributed in excess of $0.3575 per unit; and • 50 percent of amounts distributed in excess of $0.4675 per unit.

LIMITED PARTNERS' NET INCOME 26

LIMITED PARTNERS' NET INCOME PER UNIT Limited Partners' Net Income Per Unit (Policies)	6 Months Ended
	Jun. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Share, Policy [Policy Text Block]	Limited partners’ net income per unit is computed by dividing net income attributable to ONEOK Partners, L.P., after deducting the general partner’s allocation as discussed below, by the weighted-average number of outstanding limited partner units, which includes our common and Class B limited partner units. Because ONEOK has conditionally waived its right to increased quarterly distributions, until it gives 90 days notice of the withdrawal of the waiver, currently each Class B and common unit share equally in the earnings of the partnership, and neither has any liquidation or other preferences. ONEOK Partners GP owns the entire 2 percent general partnership interest in us, which entitles it to incentive distribution rights that provide for an increasing proportion of cash distributions from the Partnership as the distributions made to limited partners increase above specified levels. For purposes of our calculation of limited partners’ net income per unit, net income attributable to ONEOK Partners, L.P. is allocated to the general partner as follows: (i) an amount based upon the 2 percent general partner interest in net income attributable to ONEOK Partners, L.P.; and (ii) the amount of the general partner’s incentive distribution rights based on the total cash distributions declared for the period. The terms of our Partnership Agreement limit the general partner’s incentive distribution to the amount of available cash calculated for the period. As such, incentive distribution rights are not allocated on undistributed earnings. For additional information regarding our general partner’s incentive distribution rights, see “Partnership Agreement” in Note I of the Notes to Consolidated Financial Statements in our Annual Report.

RELATED-PARTY TRANSACTIONS RELA

RELATED-PARTY TRANSACTIONS RELATED-PARTY TRANSACTIONS (Policies)	6 Months Ended
	Jun. 30, 2015
Related Party Transactions [Abstract]
Allocation of Costs Incurred by Related Party, Policy [Policy Text Block]	ONEOK and its affiliates provide a variety of services to us under the Services Agreement, including cash management and financial services, employee benefits provided through ONEOK’s benefit plans, legal and administrative services, insurance and office space leased in ONEOK’s headquarters building and other field locations. Where costs are incurred specifically on behalf of one of our affiliates, the costs are billed directly to us by ONEOK. In other situations, the costs may be allocated to us through a variety of methods, depending upon the nature of the expense and activities. Beginning in the second quarter 2014, ONEOK allocates substantially all of its general overhead costs to us as a result of ONEOK’s separation of its natural gas distribution business and the wind down of its energy services business in the first quarter 2014. For the first quarter 2014, it is not practicable to determine what these general overhead costs would have been on a stand-alone basis. All costs directly charged or allocated to us are included in our Consolidated Statements of Income.

SEGMENTS SEGMENTS (Policies)

SEGMENTS SEGMENTS (Policies)	6 Months Ended
	Jun. 30, 2015
Segment Accounting Policies [Abstract]
Segment Reporting, Policy [Policy Text Block]	Accounting Policies - We evaluate performance based principally on each segment’s operating income and equity earnings. The accounting policies of the segments are described in Note A of the Notes to Consolidated Financial Statements in our Annual Report. Intersegment and affiliate sales are recorded on the same basis as sales to unaffiliated customers. Net margin is comprised of total revenues less cost of sales and fuel. Cost of sales and fuel includes commodity purchases, fuel, storage and transportation costs. As a result of ONEOK’s separation of its natural gas distribution business into a stand-alone publicly traded company, ONE Gas, on January 31, 2014, transactions with ONE Gas subsequent to the separation are reflected as sales to unaffiliated customers.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Recurring Fair Value Measurements	Recurring Fair Value Measurements - The following tables set forth our recurring fair value measurements for the periods indicated: June 30, 2015 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net (b) ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 24,510 $ — $ 6,832 $ 31,342 $ (12,867 ) $ 18,475 Physical contracts — — 6,448 6,448 — 6,448 Interest-rate contracts — 6,961 — 6,961 — 6,961 Total derivative assets $ 24,510 $ 6,961 $ 13,280 $ 44,751 $ (12,867 ) $ 31,884 Derivative liabilities Commodity contracts Financial contracts $ (4,475 ) $ — $ (2,639 ) $ (7,114 ) $ 7,114 $ — Physical contracts — — (254 ) (254 ) — (254 ) Total derivative liabilities $ (4,475 ) $ — $ (2,893 ) $ (7,368 ) $ 7,114 $ (254 ) (a) - Our derivative assets and liabilities are presented in our Consolidated Balance Sheets on a net basis. We net derivative assets and liabilities when a legally enforceable master-netting arrangement exists between the counterparty to a derivative contract and us. At June 30, 2015 , we had $5.8 million of cash held from various counterparties and no cash collateral posted. (b) - Included in other current assets, other assets, other current liabilities or deferred credits and other liabilities in our Consolidated Balance Sheets. December 31, 2014 Level 1 Level 2 Level 3 Total - Gross Netting (a) Total - Net (b) ( Thousands of dollars ) Derivative assets Commodity contracts Financial contracts $ 42,880 $ — $ 354 $ 43,234 $ (25,979 ) $ 17,255 Physical contracts — — 9,922 9,922 — 9,922 Interest-rate contracts — 2,288 — 2,288 — 2,288 Total derivative assets $ 42,880 $ 2,288 $ 10,276 $ 55,444 $ (25,979 ) $ 29,465 Derivative liabilities Commodity contracts Financial contracts $ (169 ) $ — $ (968 ) $ (1,137 ) $ 1,137 $ — Physical contracts — — (23 ) (23 ) — (23 ) Interest-rate contracts — (44,843 ) — (44,843 ) — (44,843 ) Total derivative liabilities $ (169 ) $ (44,843 ) $ (991 ) $ (46,003 ) $ 1,137 $ (44,866 ) (a) - Our derivative assets and liabilities are presented in our Consolidated Balance Sheets on a net basis. We net derivative assets and liabilities when a legally enforceable master-netting arrangement exists between the counterparty to a derivative contract and us. At December 31, 2014, we had $24.8 million of cash held from various counterparties and no cash collateral posted. (b) - Included in other current assets, other assets or other current liabilities in our Consolidated Balance Sheets.
Reconciliation of Level 3 Fair Value Measurements	The following table sets forth a reconciliation of our Level 3 fair value measurements for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, Derivative Assets (Liabilities) 2015 2014 2015 2014 ( Thousands of dollars ) Net assets (liabilities) at beginning of period $ 7,040 $ 1,972 $ 9,285 $ (782 ) Total realized/unrealized gains (losses): Included in earnings (a) (159 ) 33 110 (895 ) Included in other comprehensive income (loss) 3,506 (3,318 ) 992 (3,370 ) Purchases, issuances and settlements — — — 3,734 Net assets (liabilities) at end of period $ 10,387 $ (1,313 ) $ 10,387 $ (1,313 ) (a) - Included in commodity sales revenues in our Consolidated Statements of Income.

RISK MANAGEMENT AND HEDGING A30

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES (Tables)	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position	The following table sets forth the fair values of our derivative instruments for the periods indicated: June 30, 2015 December 31, 2014 Assets (a) (Liabilities) (a) Assets (a) (Liabilities) (a) ( Thousands of dollars ) Derivatives designated as hedging instruments Commodity contracts Financial contracts $ 30,656 $ (6,779 ) $ 43,234 $ (1,137 ) Physical contracts 6,448 (254 ) 9,922 — Interest-rate contracts 6,961 — 2,288 (44,843 ) Total derivatives designated as hedging instruments 44,065 (7,033 ) 55,444 (45,980 ) Derivatives not designated as hedging instruments Commodity contracts Financial contracts 686 (335 ) — — Physical contracts — — — (23 ) Total derivatives not designated as hedging instruments 686 (335 ) — (23 ) Total derivatives $ 44,751 $ (7,368 ) $ 55,444 $ (46,003 ) (a) - Included on a net basis in other current assets, other assets, other current liabilities or deferred credits and other liabilities in our Consolidated Balance Sheets.
Schedule of Notional Quantities for Derivative Instruments	The following table sets forth the notional quantities for derivative instruments held for the periods indicated: June 30, 2015 December 31, 2014 Contract Type Purchased/ Payor Sold/ Receiver Purchased/ Payor Sold/ Receiver Derivatives designated as hedging instruments: Cash flow hedges Fixed price - Natural gas ( Bcf ) Futures and swaps — (62.1 ) — (41.2 ) - Crude oil and NGLs ( MMBbl ) Futures, forwards and swaps — (4.9 ) — (0.5 ) Basis - Natural gas ( Bcf ) Futures and swaps — (62.1 ) — (41.2 ) Interest-rate contracts ( Millions of dollars ) Forward-starting swaps $ 400.0 $ — $ 900.0 $ — Derivatives not designated as hedging instruments: Fixed price - Crude oil and NGLs ( MMBbl ) Futures, forwards and swaps 0.6 (0.6 ) — —
Schedule of Cash Flow Hedges in Other Comprehensive Income (Loss)	The following table sets forth the unrealized effect of cash flow hedges recognized in other comprehensive income (loss) for the periods indicated: Three Months Ended Six Months Ended Derivatives in Cash Flow Hedging Relationships June 30, June 30, 2015 2014 2015 2014 ( Thousands of dollars ) Commodity contracts $ 1,072 $ (6,114 ) $ 11,091 $ (41,876 ) Interest-rate contracts 16,909 (26,401 ) (5,667 ) (47,094 ) Total unrealized gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion) $ 17,981 $ (32,515 ) $ 5,424 $ (88,970 )
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following table sets forth the effect of cash flow hedges in our Consolidated Statements of Income for the periods indicated: Derivatives in Cash Flow Hedging Relationships Location of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Net Income (Effective Portion) Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands of dollars ) Commodity contracts Commodity sales revenues $ 17,078 $ (5,187 ) $ 31,250 $ (31,606 ) Interest-rate contracts Interest expense (3,720 ) (2,647 ) (6,559 ) (5,236 ) Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion) $ 13,358 $ (7,834 ) $ 24,691 $ (36,842 )

EQUITY (Tables)

EQUITY (Tables)	6 Months Ended
	Jun. 30, 2015
Equity [Abstract]
Schedule of distributions made to general or limited partner	The following table shows our distributions paid during the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands, except per unit amounts ) Distribution per unit $ 0.79 $ 0.745 $ 1.58 $ 1.475 General partner distributions $ 5,955 $ 5,011 $ 11,869 $ 9,860 Incentive distributions 89,889 71,911 179,168 140,166 Distributions to general partner 95,844 76,922 191,037 150,026 Limited partner distributions to ONEOK 73,302 69,125 146,604 136,862 Limited partner distributions to other unitholders 128,583 104,506 255,794 206,161 Total distributions paid $ 297,729 $ 250,553 $ 593,435 $ 493,049
Schedule of distributions declared to general or limited partner	Distributions are declared and paid within 45 days of the completion of each quarter. The following table shows our distributions declared for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands, except per unit amounts ) Distribution per unit $ 0.79 $ 0.760 $ 1.58 $ 1.505 General partner distributions $ 6,081 $ 5,501 $ 12,036 $ 10,512 Incentive distributions 91,794 80,381 181,683 152,292 Distributions to general partner 97,875 85,882 193,719 162,804 Limited partner distributions to ONEOK 73,302 70,519 146,604 139,646 Limited partner distributions to other unitholders 132,862 118,644 261,445 223,150 Total distributions declared $ 304,039 $ 275,045 $ 601,768 $ 525,600
Schedule of Stockholders Equity [Table Text Block]	The following table sets forth the changes in equity attributable to us and our noncontrolling interests, including other comprehensive income, net of tax, for the periods indicated: Three Months Ended Six Months Ended June 30, 2015 June 30, 2015 ONEOK Partners, L.P. Partners ’ Equity Noncontrolling Interests in Consolidated Subsidiaries Total Equity ONEOK Partners, L.P. Partners ’ Equity Noncontrolling Interests in Consolidated Subsidiaries Total Equity ( Thousands of dollars ) Beginning balance $ 5,848,473 $ 167,129 $ 6,015,602 $ 5,950,838 $ 167,937 $ 6,118,775 Net income 209,770 1,840 211,610 355,364 3,278 358,642 Other comprehensive income (loss) 4,623 — 4,623 (19,267 ) — (19,267 ) Issuance of common units 203,454 — 203,454 273,991 — 273,991 Contribution from general partner 4,584 — 4,584 5,684 — 5,684 Distributions paid (297,729 ) (2,448 ) (300,177 ) (593,435 ) (4,694 ) (598,129 ) Other — 38 38 — 38 38 Ending balance $ 5,973,175 $ 166,559 $ 6,139,734 $ 5,973,175 $ 166,559 $ 6,139,734

ACCUMULATED OTHER COMPREHENSI32

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ACCUMULATED OTHER COMPREHENSIVE INCOME (Tables)	6 Months Ended
	Jun. 30, 2015
Accumulated other comprehensive income (loss)	The following table sets forth the balance in accumulated other comprehensive loss for the period indicated: Accumulated Other Comprehensive Loss (a) ( Thousands of dollars ) January 1, 2015 $ (91,823 ) Other comprehensive loss before reclassifications 5,424 Amounts reclassified from accumulated other comprehensive loss (24,691 ) Net current-period other comprehensive loss attributable to ONEOK Partners (19,267 ) June 30, 2015 $ (111,090 ) (a) - All amounts are attributable to unrealized losses in risk-management assets/liabilities.
Disclosure of Reclassification Amount [Text Block]	The following table sets forth the effect of reclassifications from accumulated other comprehensive income (loss) in our Consolidated Statements of Income for the periods indicated: Details about Accumulated Other Components Three Months Ended June 30, Six Months Ended June 30, Affected Line Item in the Income 2015 2014 2015 2014 ( Thousands of dollars ) Unrealized (gains) losses on risk-management assets/liabilities Commodity contracts $ (17,078 ) $ 5,187 $ (31,250 ) $ 31,606 Commodity sales revenues Interest-rate contracts 3,720 2,647 6,559 5,236 Interest expense Total reclassifications for the period attributable to ONEOK Partners $ (13,358 ) $ 7,834 $ (24,691 ) $ 36,842 Net income attributable to ONEOK Partners

UNCONSOLIDATED AFFILIATES (Tabl

UNCONSOLIDATED AFFILIATES (Tables)	6 Months Ended
	Jun. 30, 2015
Equity Method Investee [Member]
Schedule of Equity Method Investments [Line Items]
Equity in Net Earnings from Investments [Table Text Block]	The following table sets forth our equity in net earnings from investments for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands of dollars ) Share of investee earnings Northern Border Pipeline $ 15,273 $ 15,877 $ 34,975 $ 39,286 Overland Pass Pipeline Company 9,623 4,121 16,510 8,852 Other 5,144 5,437 9,476 10,956 Equity in net earnings from investments $ 30,040 $ 25,435 $ 60,961 $ 59,094
Equity Method Investments [Member]
Schedule of Equity Method Investments [Line Items]
Equity in Net Earnings from Investments [Table Text Block]	The following table sets forth summarized combined financial information of our unconsolidated affiliates for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands of dollars ) Income Statement Operating revenues $ 125,738 $ 121,509 $ 255,319 $ 276,788 Operating expenses $ 55,959 $ 51,870 $ 113,538 $ 123,549 Net income $ 62,643 $ 60,878 $ 129,002 $ 139,551 Distributions paid to us $ 41,354 $ 42,579 $ 80,783 $ 77,649

RELATED-PARTY TRANSACTIONS (Tab

RELATED-PARTY TRANSACTIONS (Tables)	6 Months Ended
	Jun. 30, 2015
Related Party Transactions [Abstract]
Schedule of Related Party Transactions [Table Text Block]	The following table sets forth the transactions with related parties for the periods indicated: Three Months Ended Six Months Ended June 30, June 30, 2015 2014 2015 2014 ( Thousands of dollars ) Revenues $ — $ — $ — $ 53,526 Expenses Cost of sales and fuel $ — $ — $ — $ 10,835 Operating expenses 86,741 78,705 176,269 155,951 Total expenses $ 86,741 $ 78,705 $ 176,269 $ 166,786

SEGMENTS (Tables)

SEGMENTS (Tables)	6 Months Ended
	Jun. 30, 2015
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Selected Financial Information by Reportable Segment	The following tables set forth certain selected financial information for our operating segments for the periods indicated: Three Months Ended June 30, 2015 Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Other and Eliminations Total ( Thousands of dollars ) Sales to unaffiliated customers $ 279,498 $ 1,769,580 $ 78,429 $ — $ 2,127,507 Intersegment revenues 180,564 79,295 1,683 (261,542 ) — Total revenues $ 460,062 $ 1,848,875 $ 80,112 $ (261,542 ) $ 2,127,507 Net margin $ 137,135 $ 313,383 $ 74,107 $ (211 ) $ 524,414 Operating costs 63,550 77,410 25,240 412 166,612 Depreciation and amortization 35,952 39,433 10,814 — 86,199 Gain (loss) on sale of assets 195 (73 ) — — 122 Operating income $ 37,828 $ 196,467 $ 38,053 $ (623 ) $ 271,725 Equity in net earnings from investments $ 4,922 $ 9,693 $ 15,425 $ — $ 30,040 Capital expenditures $ 205,434 $ 59,087 $ 15,613 $ 5,226 $ 285,360 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $227.5 million , of which $186.4 million was related to sales within the segment, net margin of $128.5 million and operating income of $73.6 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $64.1 million , net margin of $57.1 million and operating income of $25.7 million . Three Months Ended June 30, 2014 Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Other and Eliminations Total ( Thousands of dollars ) Sales to unaffiliated customers $ 374,112 $ 2,612,336 $ 79,287 $ — $ 3,065,735 Intersegment revenues 349,253 52,974 2,698 (404,925 ) — Total revenues $ 723,365 $ 2,665,310 $ 81,985 $ (404,925 ) $ 3,065,735 Net margin $ 154,970 $ 266,145 $ 75,471 $ (2,253 ) $ 494,333 Operating costs 59,386 76,081 27,287 (2,109 ) 160,645 Depreciation and amortization 29,443 31,109 10,895 — 71,447 Gain (loss) on sale of assets (28 ) 11 — 1 (16 ) Operating income $ 66,113 $ 158,966 $ 37,289 $ (143 ) $ 262,225 Equity in net earnings from investments $ 5,099 $ 4,459 $ 15,877 $ — $ 25,435 Capital expenditures $ 168,208 $ 210,676 $ 8,710 $ 1,819 $ 389,413 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $153.3 million , of which $135.3 million was related to sales within the segment, net margin of $84.4 million and operating income of $34.5 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $68.3 million , net margin of $59.5 million and operating income of $26.1 million . Six Months Ended June 30, 2015 Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Other and Eliminations Total ( Thousands of dollars ) Sales to unaffiliated customers $ 567,514 $ 3,204,393 $ 160,359 $ — $ 3,932,266 Intersegment revenues 348,171 140,574 3,302 (492,047 ) — Total revenues $ 915,685 $ 3,344,967 $ 163,661 $ (492,047 ) $ 3,932,266 Net margin $ 261,827 $ 580,610 $ 143,230 $ (358 ) $ 985,309 Operating costs 132,760 159,656 52,482 (127 ) 344,771 Depreciation and amortization 71,749 78,727 21,570 — 172,046 Gain (loss) on sale of assets 196 (81 ) 1 — 116 Operating income $ 57,514 $ 342,146 $ 69,179 $ (231 ) $ 468,608 Equity in net earnings from investments $ 9,161 $ 16,673 $ 35,127 $ — $ 60,961 Investments in unconsolidated affiliates $ 252,468 $ 485,381 $ 408,558 $ — $ 1,146,407 Total assets $ 5,007,456 $ 8,139,588 $ 1,841,321 $ 8,288 $ 14,996,653 Noncontrolling interests in consolidated subsidiaries $ 4,065 $ 162,494 $ — $ — $ 166,559 Capital expenditures $ 460,735 $ 132,553 $ 25,205 $ 9,903 $ 628,396 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $437.3 million , of which $351.7 million was related to sales within the segment, net margin of $252.6 million and operating income of $138.5 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $133.4 million , net margin of $118.0 million and operating income of $53.1 million . Six Months Ended June 30, 2014 Natural Gas Gathering and Processing Natural Gas Liquids (a) Natural Gas Pipelines (b) Other and Eliminations Total ( Thousands of dollars ) Sales to unaffiliated customers $ 721,128 $ 5,282,991 $ 170,393 $ — $ 6,174,512 Sales to affiliated customers 41,214 — 12,312 — 53,526 Intersegment revenues 723,148 94,131 4,073 (821,352 ) — Total revenues $ 1,485,490 $ 5,377,122 $ 186,778 $ (821,352 ) $ 6,228,038 Net margin $ 308,524 $ 535,123 $ 168,960 $ (8,640 ) $ 1,003,967 Operating costs 124,210 141,183 54,749 (9,314 ) 310,828 Depreciation and amortization 58,285 58,187 21,710 — 138,182 Gain (loss) on sale of assets (47 ) (37 ) (83 ) 166 (1 ) Operating income $ 125,982 $ 335,716 $ 92,418 $ 840 $ 554,956 Equity in net earnings from investments $ 10,585 $ 9,223 $ 39,286 $ — $ 59,094 Investments in unconsolidated affiliates $ 329,726 $ 485,960 $ 396,722 $ — $ 1,212,408 Total assets $ 4,276,593 $ 7,363,417 $ 1,852,901 $ 255,604 $ 13,748,515 Noncontrolling interests in consolidated subsidiaries $ 4,493 $ — $ — $ 15 $ 4,508 Capital expenditures $ 291,099 $ 483,739 $ 15,337 $ 2,239 $ 792,414 (a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $289.1 million , of which $246.9 million was related to sales within the segment, net margin of $169.1 million and operating income of $79.6 million . (b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $149.6 million , net margin of $128.1 million and operating income of $61.2 million .

SUPPLEMENTAL CONDENSED CONSOL36

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Statements of Income	Condensed Consolidating Statements of Income Three Months Ended June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ 1,722.3 $ — $ 1,722.3 Services — — 405.3 — 405.3 Total revenues — — 2,127.6 — 2,127.6 Cost of sales and fuel — — 1,603.1 — 1,603.1 Net margin — — 524.5 — 524.5 Operating expenses Operations and maintenance — — 143.1 — 143.1 Depreciation and amortization — — 86.2 — 86.2 General taxes — — 23.5 — 23.5 Total operating expenses — — 252.8 — 252.8 Gain (loss) on sale of assets — — 0.1 — 0.1 Operating income — — 271.8 — 271.8 Equity in net earnings from investments 209.8 209.8 14.6 (404.2 ) 30.0 Allowance for equity funds used during construction — — 0.7 — 0.7 Other income (expense), net 95.3 95.3 (1.9 ) (190.6 ) (1.9 ) Interest expense, net (95.3 ) (95.3 ) (86.5 ) 190.6 (86.5 ) Income before income taxes 209.8 209.8 198.7 (404.2 ) 214.1 Income taxes — — (2.5 ) — (2.5 ) Net income 209.8 209.8 196.2 (404.2 ) 211.6 Less: Net income attributable to noncontrolling interests — — 1.8 — 1.8 Net income attributable to ONEOK Partners, L.P. $ 209.8 $ 209.8 $ 194.4 $ (404.2 ) $ 209.8 Three Months Ended June 30, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ 2,715.1 $ — $ 2,715.1 Services — — 350.6 — 350.6 Total revenues — — 3,065.7 — 3,065.7 Cost of sales and fuel — — 2,571.4 — 2,571.4 Net margin — — 494.3 — 494.3 Operating expenses Operations and maintenance — — 142.7 — 142.7 Depreciation and amortization — — 71.4 — 71.4 General taxes — — 18.0 — 18.0 Total operating expenses — — 232.1 — 232.1 Gain (loss) on sale of assets — — — — — Operating income — — 262.2 — 262.2 Equity in net earnings from investments 214.4 214.4 9.6 (413.0 ) 25.4 Allowance for equity funds used during construction — — 1.3 — 1.3 Other income (expense), net 83.1 83.1 1.8 (166.2 ) 1.8 Interest expense, net (83.1 ) (83.1 ) (73.0 ) 166.2 (73.0 ) Income before income taxes 214.4 214.4 201.9 (413.0 ) 217.7 Income taxes — — (3.2 ) — (3.2 ) Net income 214.4 214.4 198.7 (413.0 ) 214.5 Less: Net income attributable to noncontrolling interests — — 0.1 — 0.1 Net income attributable to ONEOK Partners, L.P. $ 214.4 $ 214.4 $ 198.6 $ (413.0 ) $ 214.4 Six Months Ended June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ 3,158.0 $ — $ 3,158.0 Services — — 774.3 — 774.3 Total revenues — — 3,932.3 — 3,932.3 Cost of sales and fuel — — 2,947.0 — 2,947.0 Net margin — — 985.3 — 985.3 Operating expenses Operations and maintenance — — 298.3 — 298.3 Depreciation and amortization — — 172.0 — 172.0 General taxes — — 46.5 — 46.5 Total operating expenses — — 516.8 — 516.8 Gain (loss) on sale of assets — — 0.1 — 0.1 Operating income — — 468.6 — 468.6 Equity in net earnings from investments 355.4 355.4 25.8 (675.6 ) 61.0 Allowance for equity funds used during construction — — 1.5 — 1.5 Other income (expense), net 182.1 182.1 — (364.2 ) — Interest expense, net (182.1 ) (182.1 ) (167.2 ) 364.2 (167.2 ) Income before income taxes 355.4 355.4 328.7 (675.6 ) 363.9 Income taxes — — (5.3 ) — (5.3 ) Net income 355.4 355.4 323.4 (675.6 ) 358.6 Less: Net income attributable to noncontrolling interests — — 3.2 — 3.2 Net income attributable to ONEOK Partners, L.P. $ 355.4 $ 355.4 $ 320.2 $ (675.6 ) $ 355.4 Six Months Ended June 30, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Revenues Commodity sales $ — $ — $ 5,521.8 $ — $ 5,521.8 Services — — 706.2 — 706.2 Total revenues — — 6,228.0 — 6,228.0 Cost of sales and fuel — — 5,224.0 — 5,224.0 Net margin — — 1,004.0 — 1,004.0 Operating expenses Operations and maintenance — — 273.2 — 273.2 Depreciation and amortization — — 138.2 — 138.2 General taxes — — 37.6 — 37.6 Total operating expenses — — 449.0 — 449.0 Gain (loss) on sale of assets — — — — — Operating income — — 555.0 — 555.0 Equity in net earnings from investments 479.8 479.8 19.8 (920.3 ) 59.1 Allowance for equity funds used during construction — — 12.2 — 12.2 Other income (expense), net 165.8 165.8 2.4 (331.6 ) 2.4 Interest expense, net (165.8 ) (165.8 ) (141.3 ) 331.6 (141.3 ) Income before income taxes 479.8 479.8 448.1 (920.3 ) 487.4 Income taxes — — (7.4 ) — (7.4 ) Net income 479.8 479.8 440.7 (920.3 ) 480.0 Less: Net income attributable to noncontrolling interests — — 0.2 — 0.2 Net income attributable to ONEOK Partners, L.P. $ 479.8 $ 479.8 $ 440.5 $ (920.3 ) $ 479.8
Condensed Consolidating Statements of Comprehensive Income	Condensed Consolidating Statements of Comprehensive Income Three Months Ended June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 209.8 $ 209.8 $ 196.2 $ (404.2 ) $ 211.6 Other comprehensive income (loss) Unrealized gains (losses) on derivatives 18.0 1.1 1.1 (2.2 ) 18.0 Realized (gains) losses on derivatives recognized in net income (13.4 ) (17.1 ) (17.1 ) 34.2 (13.4 ) Total other comprehensive income (loss) 4.6 (16.0 ) (16.0 ) 32.0 4.6 Comprehensive income 214.4 193.8 180.2 (372.2 ) 216.2 Less: Comprehensive income attributable to noncontrolling interests — — 1.8 — 1.8 Comprehensive income attributable to ONEOK Partners, L.P. $ 214.4 $ 193.8 $ 178.4 $ (372.2 ) $ 214.4 Three Months Ended June 30, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 214.4 $ 214.4 $ 198.7 $ (413.0 ) $ 214.5 Other comprehensive income (loss) Unrealized gains (losses) on derivatives (32.5 ) (6.1 ) (6.1 ) 12.2 (32.5 ) Realized (gains) losses on derivatives recognized in net income 7.8 5.2 5.2 (10.4 ) 7.8 Total other comprehensive income (loss) (24.7 ) (0.9 ) (0.9 ) 1.8 (24.7 ) Comprehensive income 189.7 213.5 197.8 (411.2 ) 189.8 Less: Comprehensive income attributable to noncontrolling interests — — 0.1 — 0.1 Comprehensive income attributable to ONEOK Partners, L.P. $ 189.7 $ 213.5 $ 197.7 $ (411.2 ) $ 189.7 Six Months Ended June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 355.4 $ 355.4 $ 323.4 $ (675.6 ) $ 358.6 Other comprehensive income (loss) Unrealized gains (losses) on derivatives 5.4 11.1 11.1 (22.2 ) 5.4 Realized (gains) losses on derivatives recognized in net income (24.7 ) (31.3 ) (31.3 ) 62.6 (24.7 ) Total other comprehensive income (loss) (19.3 ) (20.2 ) (20.2 ) 40.4 (19.3 ) Comprehensive income 336.1 335.2 303.2 (635.2 ) 339.3 Less: Comprehensive income attributable to noncontrolling interests — — 3.2 — 3.2 Comprehensive income attributable to ONEOK Partners, L.P. $ 336.1 $ 335.2 $ 300.0 $ (635.2 ) $ 336.1 Six Months Ended June 30, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Net income $ 479.8 $ 479.8 $ 440.7 $ (920.3 ) $ 480.0 Other comprehensive income (loss) Unrealized gains (losses) on derivatives (89.0 ) (41.9 ) (41.9 ) 83.8 (89.0 ) Realized (gains) losses on derivatives recognized in net income 36.9 31.6 31.6 (63.2 ) 36.9 Total other comprehensive income (loss) (52.1 ) (10.3 ) (10.3 ) 20.6 (52.1 ) Comprehensive income 427.7 469.5 430.4 (899.7 ) 427.9 Less: Comprehensive income attributable to noncontrolling interests — — 0.2 — 0.2 Comprehensive income attributable to ONEOK Partners, L.P. $ 427.7 $ 469.5 $ 430.2 $ (899.7 ) $ 427.7
Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheets June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total Assets ( Millions of dollars ) Current assets Cash and cash equivalents $ — $ 53.1 $ — $ — $ 53.1 Accounts receivable, net — — 683.7 — 683.7 Affiliate receivables — — 1.8 — 1.8 Natural gas and natural gas liquids in storage — — 150.1 — 150.1 Commodity imbalances — — 31.2 — 31.2 Materials and supplies — — 60.5 — 60.5 Other current assets 0.7 — 56.2 — 56.9 Total current assets 0.7 53.1 983.5 — 1,037.3 Property, plant and equipment Property, plant and equipment — — 13,949.9 — 13,949.9 Accumulated depreciation and amortization — — 1,995.9 — 1,995.9 Net property, plant and equipment — — 11,954.0 — 11,954.0 Investments and other assets Investments in unconsolidated affiliates 3,989.8 5,756.1 772.2 (9,371.7 ) 1,146.4 Intercompany notes receivable 9,696.4 7,877.0 — (17,573.4 ) — Goodwill and intangible assets — — 830.8 — 830.8 Other assets 7.0 — 21.2 — 28.2 Total investments and other assets 13,693.2 13,633.1 1,624.2 (26,945.1 ) 2,005.4 Total assets $ 13,693.9 $ 13,686.2 $ 14,561.7 $ (26,945.1 ) $ 14,996.7 Liabilities and equity Current liabilities Current maturities of long-term debt $ 650.0 $ — $ 7.7 $ — $ 657.7 Notes payable 870.5 — — — 870.5 Accounts payable — — 687.3 — 687.3 Affiliate payables — — 28.3 — 28.3 Commodity imbalances — — 91.6 — 91.6 Accrued interest 102.2 — — — 102.2 Other current liabilities — — 127.0 — 127.0 Total current liabilities 1,622.7 — 941.9 — 2,564.6 Intercompany debt — 9,696.4 7,877.0 (17,573.4 ) — Long-term debt, excluding current maturities 6,098.0 — 48.0 — 6,146.0 Deferred credits and other liabilities — — 146.3 — 146.3 Commitments and contingencies Equity Equity excluding noncontrolling interests in consolidated subsidiaries 5,973.2 3,989.8 5,381.9 (9,371.7 ) 5,973.2 Noncontrolling interests in consolidated subsidiaries — — 166.6 — 166.6 Total equity 5,973.2 3,989.8 5,548.5 (9,371.7 ) 6,139.8 Total liabilities and equity $ 13,693.9 $ 13,686.2 $ 14,561.7 $ (26,945.1 ) $ 14,996.7 December 31, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total Assets ( Millions of dollars ) Current assets Cash and cash equivalents $ — $ 42.5 $ — $ — $ 42.5 Accounts receivable, net — — 735.8 — 735.8 Affiliate receivables — — 8.6 — 8.6 Natural gas and natural gas liquids in storage — — 134.1 — 134.1 Commodity imbalances — — 64.8 — 64.8 Materials and supplies — — 55.8 — 55.8 Other current assets 1.9 — 42.5 — 44.4 Total current assets 1.9 42.5 1,041.6 — 1,086.0 Property, plant and equipment Property, plant and equipment — — 13,377.6 — 13,377.6 Accumulated depreciation and amortization — — 1,842.1 — 1,842.1 Net property, plant and equipment — — 11,535.5 — 11,535.5 Investments and other assets Investments in unconsolidated affiliates 4,248.0 5,469.8 746.1 (9,331.3 ) 1,132.6 Intercompany notes receivable 8,843.3 7,579.0 — (16,422.3 ) — Goodwill and intangible assets — — 822.4 — 822.4 Other assets 2.1 — 21.8 — 23.9 Total investments and other assets 13,093.4 13,048.8 1,590.3 (25,753.6 ) 1,978.9 Total assets $ 13,095.3 $ 13,091.3 $ 14,167.4 $ (25,753.6 ) $ 14,600.4 Liabilities and equity Current liabilities Current maturities of long-term debt $ — $ — $ 7.7 $ — $ 7.7 Notes payable 1,055.3 — — — 1,055.3 Accounts payable — — 874.7 — 874.7 Affiliate payables — — 36.1 — 36.1 Commodity imbalances — — 104.7 — 104.7 Accrued interest 92.0 — — — 92.0 Other current liabilities 44.8 — 120.8 — 165.6 Total current liabilities 1,192.1 — 1,144.0 — 2,336.1 Intercompany debt — 8,843.3 7,579.0 (16,422.3 ) — Long-term debt, excluding current maturities 5,952.4 — 51.9 — 6,004.3 Deferred credits and other liabilities — — 141.3 — 141.3 Commitments and contingencies Equity Equity excluding noncontrolling interests in consolidated subsidiaries 5,950.8 4,248.0 5,083.3 (9,331.3 ) 5,950.8 Noncontrolling interests in consolidated subsidiaries — — 167.9 — 167.9 Total equity 5,950.8 4,248.0 5,251.2 (9,331.3 ) 6,118.7 Total liabilities and equity $ 13,095.3 $ 13,091.3 $ 14,167.4 $ (25,753.6 ) $ 14,600.4
Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statements of Cash Flows Six Months Ended June 30, 2015 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Operating activities Cash provided by operating activities $ 550.2 $ 35.0 $ 388.6 $ (593.5 ) $ 380.3 Investing activities Capital expenditures (less allowance for equity funds used during construction) — — (628.4 ) — (628.4 ) Contributions to unconsolidated affiliates — — (33.2 ) — (33.2 ) Distributions received from unconsolidated affiliates in excess of cumulative earnings — 12.4 6.4 — 18.8 Proceeds from sale of assets — — 0.7 — 0.7 Other — — (12.6 ) — (12.6 ) Cash provided by (used in) investing activities — 12.4 (667.1 ) — (654.7 ) Financing activities Cash distributions: General and limited partners (593.5 ) (593.5 ) — 593.5 (593.5 ) Noncontrolling interests — — (4.7 ) — (4.7 ) Borrowing (repayment) of notes payable, net (184.8 ) — — — (184.8 ) Issuance of long-term debt, net of discounts 798.9 — — — 798.9 Debt financing costs (7.9 ) — — — (7.9 ) Intercompany borrowings (advances), net (843.7 ) 556.7 287.0 — — Repayment of long-term debt — — (3.8 ) — (3.8 ) Issuance of common units, net of issuance costs 275.1 — — — 275.1 Contribution from general partner 5.7 — — — 5.7 Cash provided by (used in) financing activities (550.2 ) (36.8 ) 278.5 593.5 285.0 Change in cash and cash equivalents — 10.6 — — 10.6 Cash and cash equivalents at beginning of period — 42.5 — — 42.5 Cash and cash equivalents at end of period $ — $ 53.1 $ — $ — $ 53.1 Six Months Ended June 30, 2014 ( Unaudited ) Parent Guarantor Subsidiary Combined Non-Guarantor Subsidiaries Consolidating Entries Total ( Millions of dollars ) Operating activities Cash provided by operating activities $ 505.3 $ 39.3 $ 482.6 $ (493.1 ) $ 534.1 Investing activities Capital expenditures (less allowance for equity funds used during construction) — — (792.4 ) — (792.4 ) Cash paid for acquisitions — — (14.0 ) — (14.0 ) Contributions to unconsolidated affiliates — — (1.1 ) — (1.1 ) Distributions received from unconsolidated affiliates in excess of cumulative earnings — 8.1 8.4 — 16.5 Proceeds from sale of assets — — 0.3 — 0.3 Cash provided by (used in) investing activities — 8.1 (798.8 ) — (790.7 ) Financing activities Cash distributions: General and limited partners (493.1 ) (493.1 ) — 493.1 (493.1 ) Noncontrolling interests — — (0.2 ) — (0.2 ) Borrowing (repayment) of notes payable, net — — — — — Intercompany borrowings (advances), net (909.4 ) 589.2 320.2 — — Repayment of long-term debt — — (3.8 ) — (3.8 ) Issuance of common units, net of issuance costs 878.8 — — — 878.8 Contribution from general partner 18.4 — — — 18.4 Cash provided by (used in) financing activities (505.3 ) 96.1 316.2 493.1 400.1 Change in cash and cash equivalents — 143.5 — — 143.5 Cash and cash equivalents at beginning of period — 134.5 — — 134.5 Cash and cash equivalents at end of period $ — $ 278.0 $ — $ — $ 278.0

SUMMARY OF SIGNIFICANT ACCOUN37

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Part 1 (Details) - Dec. 31, 2014 - USD ($) $ in Millions	Total
West Texas LPG and Mesquite Systems [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Business Acquisition, Effective Date of Acquisition	Nov. 28, 2014
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest	$ 800
West Texas LPG Pipeline Limited Partnership [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Business Acquisition, Description of Acquired Entity	80 percent interest
Mesquite Pipeline [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	100.00%

SUMMARY OF SIGNIFICANT ACCOUN38

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Part 2 (Details) $ in Millions	12 Months Ended
	Dec. 31, 2014USD ($)
Long-term Debt [Member] | Accounting Standards Update 2015-03 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 34.1

FAIR VALUE MEASUREMENTS - Part

FAIR VALUE MEASUREMENTS - Part 1 (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes, Fair Value	$ 7,000,000	$ 6,400,000
Senior Notes, Book Value	6,800,000	6,000,000
Cash collateral held	5,800	24,800
Cash collateral posted	0	0
Fair Value, Measurements, Recurring [Member]
Derivative assets
Commodity contracts - financial	18,475	17,255
Commodity contracts - physical	6,448	9,922
Interest-rate contracts	6,961	2,288
Total derivative assets	31,884	29,465
Derivative liabilities
Commodity contracts - financial	0	0
Commodity contracts - physical	(254)	(23)
Interest-rate contracts		(44,843)
Total derivative liabilities	(254)	(44,866)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative assets
Commodity contracts - financial	24,510	42,880
Commodity contracts - physical	0	0
Interest-rate contracts	0	0
Total derivative assets	24,510	42,880
Derivative liabilities
Commodity contracts - financial	(4,475)	(169)
Commodity contracts - physical	0	0
Interest-rate contracts		0
Total derivative liabilities	(4,475)	(169)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative assets
Commodity contracts - financial	0	0
Commodity contracts - physical	0	0
Interest-rate contracts	6,961	2,288
Total derivative assets	6,961	2,288
Derivative liabilities
Commodity contracts - financial	0	0
Commodity contracts - physical	0	0
Interest-rate contracts		(44,843)
Total derivative liabilities	0	(44,843)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative assets
Commodity contracts - financial	6,832	354
Commodity contracts - physical	6,448	9,922
Interest-rate contracts	0	0
Total derivative assets	13,280	10,276
Derivative liabilities
Commodity contracts - financial	(2,639)	(968)
Commodity contracts - physical	(254)	(23)
Interest-rate contracts		0
Total derivative liabilities	(2,893)	(991)
Fair Value, Measurements, Recurring [Member] | Total Gross, Fair Value Disclosure [Member]
Derivative assets
Commodity contracts - financial	31,342	43,234
Commodity contracts - physical	6,448	9,922
Interest-rate contracts	6,961	2,288
Total derivative assets	44,751	55,444
Derivative liabilities
Commodity contracts - financial	(7,114)	(1,137)
Commodity contracts - physical	(254)	(23)
Interest-rate contracts		(44,843)
Total derivative liabilities	(7,368)	(46,003)
Fair Value, Measurements, Recurring [Member] | Netting [Member]
Derivative assets
Commodity contracts - financial	(12,867)	(25,979)
Commodity contracts - physical	0	0
Interest-rate contracts	0	0
Total derivative assets	(12,867)	(25,979)
Derivative liabilities
Commodity contracts - financial	7,114	1,137
Commodity contracts - physical	0	0
Interest-rate contracts		0
Total derivative liabilities	$ 7,114	$ 1,137

FAIR VALUE MEASUREMENTS - Par40

FAIR VALUE MEASUREMENTS - Part 2 (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair Value, Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]
Transfers between levels	$ 0	$ 0	$ 0	$ 0
Derivative Financial Instruments Assets Liabilities Net [Member]
Fair Value, Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]
Net assets (liabilities) at beginning of period	7,040	1,972	9,285	(782)
Total realized/unrealized gains (losses): [Abstract]
Included in earnings	(159)	33	110	(895)
Included in other comprehensive income (loss)	3,506	(3,318)	992	(3,370)
Purchases, issuances and settlements	0	0	0	3,734
Net assets (liabilities) at end of period	$ 10,387	$ (1,313)	$ 10,387	$ (1,313)

RISK MANAGEMENT AND HEDGING A41

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES Part 1 (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Derivative, Net Liability Position, Aggregate Fair Value	$ 0
Assets	44,751,000	$ 55,444,000
(Liabilities)	(7,368,000)	(46,003,000)
Natural Gas Pipelines [Member]
Derivative [Line Items]
Derivative, Fair Value, Net	0	0
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Assets	44,065,000	55,444,000
(Liabilities)	(7,033,000)	(45,980,000)
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Assets	6,961,000	2,288,000
(Liabilities)	0	(44,843,000)
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Assets	686,000	0
(Liabilities)	(335,000)	(23,000)
Financial Derivative Instrument [Member] | Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Assets	30,656,000	43,234,000
(Liabilities)	(6,779,000)	(1,137,000)
Financial Derivative Instrument [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Assets	686,000	0
(Liabilities)	(335,000)	0
Physical Derivative Instrument [Member] | Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Assets	6,448,000	9,922,000
(Liabilities)	(254,000)	0
Physical Derivative Instrument [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Assets	0	0
(Liabilities)	$ 0	$ (23,000)

RISK MANAGEMENT AND HEDGING A42

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES, Part 2 (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)MMcfMMBbls	Dec. 31, 2014USD ($)MMcfMMBbls
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount Of Cash Flow Hedge Instruments Settled	$ 500
Designated as Hedging Instrument [Member] | Futures and swaps [Member] | Natural Gas [Member] | Purchasor [Member] | Fixed Price [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | MMcf	0	0
Designated as Hedging Instrument [Member] | Futures and swaps [Member] | Natural Gas [Member] | Purchasor [Member] | Basis [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | MMcf	0	0
Designated as Hedging Instrument [Member] | Futures and swaps [Member] | Natural Gas [Member] | Sellor [Member] | Fixed Price [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | MMcf	(62,100)	(41,200)
Designated as Hedging Instrument [Member] | Futures and swaps [Member] | Natural Gas [Member] | Sellor [Member] | Basis [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | MMcf	(62,100)	(41,200)
Designated as Hedging Instrument [Member] | Futures, forwards and swaps [Member] | Crude oil and NGLs [Member] | Purchasor [Member] | Fixed Price [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | MMBbls	0	0
Designated as Hedging Instrument [Member] | Futures, forwards and swaps [Member] | Crude oil and NGLs [Member] | Sellor [Member] | Fixed Price [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | MMBbls	(4.9)	(0.5)
Designated as Hedging Instrument [Member] | Forward Starting Interest Rate Swap [Member] | Purchasor [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 400	$ 900
Notional Amount Of Cash Flow Hedge Instruments Greater Than 12 Months	400
Designated as Hedging Instrument [Member] | Forward Starting Interest Rate Swap [Member] | Sellor [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 0	$ 0
Not Designated as Hedging Instrument [Member] | Futures, forwards and swaps [Member] | Crude oil and NGLs [Member] | Purchasor [Member] | Fixed Price [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | MMBbls	0.6	0
Not Designated as Hedging Instrument [Member] | Futures, forwards and swaps [Member] | Crude oil and NGLs [Member] | Sellor [Member] | Fixed Price [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | MMBbls	(0.6)	0

RISK MANAGEMENT AND HEDGING A43

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES Part 3 (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Realized Loss On Settled Interest Rate Swaps Recorded in AOCI			$ 55,100
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (111,090)		(111,090)		$ (91,823)
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	0	$ 0	0	$ 0
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	17,981	(32,515)	5,424	(88,970)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	13,358	(7,834)	24,691	(36,842)
Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(17,078)	5,187	(31,250)	31,606
Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) On Cash Flow Hedges Net Of Tax Accumulated Other Comprehensive Income Loss	32,400		32,400
Price Risk Cash Flow Hedge Unrealized Gain (Loss) to be Reclassified During Next 12 Months	30,400		30,400
Commodity Cash Flow Hedge Gain Loss To Be Reclassified After Next 12 Months Net	2,000		2,000
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	3,720	2,647	6,559	5,236
Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of accumulated other comprehensive income (loss) attributable primarily to settled interest-rate swaps.	(149,200)		(149,200)
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	(15,500)		(15,500)
Continuing Operations [Member] | Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	1,072	(6,114)	11,091	(41,876)
Continuing Operations [Member] | Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	16,909	(26,401)	(5,667)	(47,094)
Sales [Member] | Continuing Operations [Member] | Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	17,078	(5,187)	31,250	(31,606)
Interest Expense [Member] | Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$ (3,720)	$ (2,647)	$ (6,559)	$ (5,236)

CREDIT FACILITY AND SHORT-TER44

CREDIT FACILITY AND SHORT-TERM NOTES PAYABLE (Details) - Partnership Credit Agreement [Member] $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)	Dec. 31, 2014USD ($)
Line of Credit Facility [Line Items]
Commercial Paper	$ 870.5
Letters of Credit Outstanding, Amount	14
Short-term Bank Loans and Notes Payable	0
Line of Credit Facility, Maximum Borrowing Capacity	2,400	$ 1,700
Line of Credit Facility Letters of Credit Sublimit	100
Maximum Amount Of Commercial Paper	2,400	$ 1,700
Line of Credit Facility Swingline Sublimit	$ 150
Interest rate description	borrowings, if any, will accrue at LIBOR plus 117.5 basis points
Annual fee description	the annual facility fee is 20 basis points
Indebtedness To Adjusted EBITDA Maximum	5
Acquisition price threshold for increase in permitted debt to EBITDA covenant ratio	$ 25
Indebtedness To Adjusted EBITDA From Acquisitions Maximum	5.5
Indebtedness To Adjusted EBITDA Current	4.5

LONG TERM DEBT LONG-TERM DEBT45

LONG TERM DEBT LONG-TERM DEBT (Details) - Jun. 30, 2015 - Partnership Interest [Member] - USD ($) $ in Millions	Total
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Covenant Description	These notes are governed by an indenture, dated as of September 25, 2006, between us and Wells Fargo Bank, N.A., the trustee, as supplemented. The indenture does not limit the aggregate principal amount of debt securities that may be issued and provides that debt securities may be issued from time to time in one or more additional series. The indenture contains covenants including, among other provisions, limitations on our ability to place liens on our property or assets and to sell and lease back our property. The indenture includes an event of default upon acceleration of other indebtedness of $100 million or more. Such events of default would entitle the trustee or the holders of 25 percent in aggregate principal amount of any of our outstanding senior notes to declare those notes immediately due and payable in full.
Debt Instrument, Call Feature	We may redeem our 3.8 percent senior notes due 2020 and our 4.9 percent senior notes due 2025 from the March 2015 offering at par, plus accrued and unpaid interest to the redemption date, starting one month and three months, respectively, before their maturity dates. Prior to these dates, we may redeem these notes, in whole or in part, at a redemption price equal to the principal amount, plus accrued and unpaid interest and a make-whole premium. The redemption price will never be less than 100 percent of the principal amount of the respective note plus accrued and unpaid interest to the redemption date. Our senior notes are senior unsecured obligations, ranking equally in right of payment with all of our existing and future unsecured senior indebtedness, and structurally subordinate to any of the existing and future debt and other liabilities of any nonguarantor subsidiaries.
Senior Notes, Noncurrent	$ 800
Proceeds from Debt, Net of Issuance Costs	792.3
Note Payable from Public Offering Due 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 300
Debt Instrument, Interest Rate, Stated Percentage	3.80%
Note Payable from Public Offering Due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 500
Debt Instrument, Interest Rate, Stated Percentage	4.90%
Note Payable from Public Offering Due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 650
Debt Instrument, Interest Rate, Stated Percentage	3.25%

EQUITY (Details)

EQUITY (Details) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015USD ($)$ / shares$ / unitshares	Jun. 30, 2014USD ($)$ / sharesshares	Jun. 30, 2015USD ($)$ / sharesshares	Jun. 30, 2014USD ($)$ / sharesshares	Dec. 31, 2014USD ($)
Partnership Capital Distributions [Line Items]
Key Provisions of Operating or Partnership Agreement, Description			Partnership Agreement - Available cash, as defined in our Partnership Agreement generally will be distributed to our general partner and limited partners according to their partnership percentages of 2 percent and 98 percent, respectively. Our general partner’s percentage interest in quarterly distributions is increased after certain specified target levels are met during the quarter. Under the incentive distribution provisions, as set forth in our Partnership Agreement, our general partner receives: 15 percent of amounts distributed in excess of $0.3025 per unit; 25 percent of amounts distributed in excess of $0.3575 per unit; and 50 percent of amounts distributed in excess of $0.4675 per unit.
Number of common units owned by related party (in number of units) | shares	19.8		19.8
General partnership ownership interest (in hundredths)			36.80%		37.80%
Aggregate Amount Of Common Units Available For Issuance And Sale Under The Equity Distribution Agreement			$ 650,000
Remaining Capacity of At The Market Equity Program	$ 238,000		$ 238,000
Partners Capital Account Units Sold Under Equity Distribution Agreement | shares	5.5	1.9	7.2	3
Partners capital account, beginning balance	$ 6,015,602		$ 6,118,775
Net income	211,610	$ 214,511	358,642	$ 479,979
Other Comprehensive Income (Loss)	4,623	$ (24,681)	(19,267)	$ (52,128)
Issuance of common units	203,454		273,991
Contributions from general partner	4,584		5,684
Distributions paid	(300,177)		(598,129)
Other	38		38
Partners capital account, ending balance	$ 6,139,734		$ 6,139,734		$ 6,118,775
General Partner [Member]
Partnership Capital Distributions [Line Items]
General partnership ownership interest (in hundredths)			2.00%
Distribution Declared [Member]
Partnership Capital Distributions [Line Items]
Distribution Made To Member Or Limited Parter Annualized Quarterly Distribution | $ / unit	3.16
Distribution Made to Member or Limited Partner, Distribution Date	Aug. 14, 2015
Distribution Made to Member or Limited Partner, Date of Record	Aug. 3, 2015
Distribution per unit | $ / shares	$ 0.790	$ 0.760	$ 1.580	$ 1.505
Total distributions	$ 304,039	$ 275,045	$ 601,768	$ 525,600
Distribution Declared [Member] | General Partner [Member]
Partnership Capital Distributions [Line Items]
General partner distributions	6,081	5,501	12,036	10,512
Incentive distributions	91,794	80,381	181,683	152,292
General Partners' Capital Account, Period Distribution Amount	97,875	85,882	193,719	162,804
Distribution Declared [Member] | Limited Partner [Member]
Partnership Capital Distributions [Line Items]
Partners Capital Account Distributions to Other Unitholders	132,862	118,644	261,445	223,150
Distribution Declared [Member] | ONEOK [Member]
Partnership Capital Distributions [Line Items]
Limited partner distributions	$ 73,302	$ 70,519	$ 146,604	$ 139,646
Distribution Paid [Member]
Partnership Capital Distributions [Line Items]
Distribution per unit | $ / shares	$ 0.790	$ 0.745	$ 1.580	$ 1.475
Total distributions	$ 297,729	$ 250,553	$ 593,435	$ 493,049
Distribution Paid [Member] | General Partner [Member]
Partnership Capital Distributions [Line Items]
General partner distributions	5,955	5,011	11,869	9,860
Incentive distributions	89,889	71,911	179,168	140,166
General Partners' Capital Account, Period Distribution Amount	95,844	76,922	191,037	150,026
Distribution Paid [Member] | Limited Partner [Member]
Partnership Capital Distributions [Line Items]
Partners Capital Account Distributions to Other Unitholders	128,583	104,506	255,794	206,161
Distribution Paid [Member] | ONEOK [Member]
Partnership Capital Distributions [Line Items]
Limited partner distributions	73,302	69,125	146,604	136,862
Issued under public offering [Member]
Partnership Capital Distributions [Line Items]
Proceeds from sale of interest in partnership units				$ 714,500
Public offering price of common units | $ / shares				$ 52.94
Partners' Capital Account, Units, Sold in Public Offering | shares				13.9
Contributions from general partner				$ 15,000
ONEOK Partners, L.P. Partners' Equity [Member]
Partnership Capital Distributions [Line Items]
Partners capital account, beginning balance	5,848,473		5,950,838
Net income	209,770		355,364
Other Comprehensive Income (Loss)	4,623		(19,267)
Issuance of common units	203,454		273,991
Contributions from general partner	4,584		5,684
Distributions paid	(297,729)		(593,435)
Other	0		0
Partners capital account, ending balance	5,973,175		5,973,175		5,950,838
Issued Under Equity Distribution Agreement [Member]
Partnership Capital Distributions [Line Items]
Proceeds from sale of interest in partnership units	208,100	$ 107,600	279,700	$ 164,100
Noncontrolling Interest [Member]
Partnership Capital Distributions [Line Items]
Partners capital account, beginning balance	167,129		167,937
Net income	1,840		3,278
Other Comprehensive Income (Loss)	0		0
Issuance of common units	0		0
Contributions from general partner	0		0
Distributions paid	(2,448)		(4,694)
Other	38		38
Partners capital account, ending balance	$ 166,559		$ 166,559		$ 167,937

ACCUMULATED OTHER COMPREHENSI47

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated other comprehensive loss - January 1, 2015			$ (91,823)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	$ 17,981	$ (32,515)	5,424	$ (88,970)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(13,358)	7,834	(24,691)	36,842
Net current-period other comprehensive income (loss) attributable to ONEOK Partners, L.P.	4,623	(24,681)	(19,267)	(52,128)
Accumulated other comprehensive loss - June 30, 2015	(111,090)		(111,090)
Cash Flow Hedging [Member]
Other comprehensive income (loss) before reclassifications	17,981	(32,515)	5,424	(88,970)
Amounts reclassified from accumulated other comprehensive income (loss)	13,358	(7,834)	24,691	(36,842)
Commodity Contract [Member]
Amounts reclassified from accumulated other comprehensive income (loss)	(17,078)	5,187	(31,250)	31,606
Interest Rate Contract [Member]
Amounts reclassified from accumulated other comprehensive income (loss)	3,720	2,647	6,559	5,236
Interest Rate Contract [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]
Amounts reclassified from accumulated other comprehensive income (loss)	$ (3,720)	$ (2,647)	$ (6,559)	$ (5,236)

LIMITED PARTNERS' NET INCOME 48

LIMITED PARTNERS' NET INCOME PER UNIT (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
General partnership ownership interest (in hundredths)	36.80%	37.80%
Number of days notice of withdrawal of waiver	90
General Partner [Member]
Schedule of Equity Method Investments [Line Items]
General partnership ownership interest (in hundredths)	2.00%

UNCONSOLIDATED AFFILIATES (Deta

UNCONSOLIDATED AFFILIATES (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Equity earnings (loss) from investments	$ 30,040	$ 25,435	$ 60,961	$ 59,094
Accounts Payable, Related Parties, Current	10,100		10,100		$ 20,500
Investments in unconsolidated affiliates	1,146,407	1,212,408	1,146,407	1,212,408	$ 1,132,653
Income Statement [Abstract]
Operating revenues	125,738	121,509	255,319	276,788
Operating expenses	55,959	51,870	113,538	123,549
Net income	62,643	60,878	129,002	139,551
Distributions paid to us	41,354	42,579	80,783	77,649
Northern Border Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings (loss) from investments	15,273	15,877	34,975	39,286
Overland Pass Pipeline Company [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings (loss) from investments	9,623	4,121	16,510	8,852
Other Unconsolidated Affiliate [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings (loss) from investments	5,144	5,437	9,476	10,956
Roadrunner Gas Transmission [Member]
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Equity Method Investments	33,200
Unconsolidated Affiliates [Member]
Schedule of Equity Method Investments [Line Items]
Costs and operating expenses with equity method investees	25,900	$ 14,300	45,800	$ 28,400
Powder River Basin [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	212,700		212,700
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ 130,500		$ 130,500

RELATED-PARTY TRANSACTIONS (Det

RELATED-PARTY TRANSACTIONS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Related Party Transaction [Line Items]
Contributions from general partner	$ 4,584		$ 5,684
General partnership ownership interest (in hundredths)			36.80%		37.80%
General Partner [Member]
Related Party Transaction [Line Items]
General partnership ownership interest (in hundredths)			2.00%
General Partner [Member]
Related Party Transaction [Line Items]
Contributions from general partner			$ 5,684	$ 18,300
ONEOK [Member]
Related Party Transaction [Line Items]
Revenues	0	$ 0	0	53,526
Expenses [Abstract]
Cost of sales and fuel	0	0	0	10,835
Operating expenses	86,741	78,705	176,269	155,951
Total expenses	$ 86,741	$ 78,705	$ 176,269	$ 166,786

SEGMENTS (Details)

SEGMENTS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Segment disclosure [Abstract]
Disclosure of Major Customers	For the three months ended June 30, 2015, we had one customer, BP p.l.c., from which we received $224.6 million in total revenues from all of our operating segments, or approximately 11 percent of our consolidated revenues.	For the three months ended June 30, 2014, we had no single customer from which we received 10 percent or more of our consolidated revenues.	For the six months ended June 30, 2015, we had one customer, BP p.l.c., from which we received $409.5 million in total revenues from all of our operating segments, or approximately 10 percent of our consolidated revenues.	For the six months ended June 30, 2014, we had no single customer from which we received 10 percent or more of our consolidated revenues.
Total revenues	$ 2,127,507	$ 3,065,735	$ 3,932,266	$ 6,228,038
Net Margin	524,414	494,333	985,309	1,003,967
Operating Costs	166,612	160,645	344,771	310,828
Depreciation and amortization	86,199	71,447	172,046	138,182
Gain (loss) on sale of assets	122	(16)	116	(1)
Operating income	271,725	262,225	468,608	554,956
Equity in net earnings from investments	30,040	25,435	60,961	59,094
Investments in unconsolidated affiliates	1,146,407	1,212,408	1,146,407	1,212,408	$ 1,132,653
Total Assets	14,996,653	13,748,515	14,996,653	13,748,515	14,600,400
Noncontrolling interests in consolidated subsidiaries	166,559	4,508	166,559	4,508	$ 167,937
Capital expenditures	285,360	389,413	628,396	792,414
Natural Gas Gathering and Processing [Member]
Segment disclosure [Abstract]
Total revenues	460,062	723,365	915,685	1,485,490
Net Margin	137,135	154,970	261,827	308,524
Operating Costs	63,550	59,386	132,760	124,210
Depreciation and amortization	35,952	29,443	71,749	58,285
Gain (loss) on sale of assets	195	(28)	196	(47)
Operating income	37,828	66,113	57,514	125,982
Equity in net earnings from investments	4,922	5,099	9,161	10,585
Investments in unconsolidated affiliates	252,468	329,726	252,468	329,726
Total Assets	5,007,456	4,276,593	5,007,456	4,276,593
Noncontrolling interests in consolidated subsidiaries	4,065	4,493	4,065	4,493
Capital expenditures	205,434	168,208	460,735	291,099
Natural Gas Liquids [Member]
Segment disclosure [Abstract]
Total revenues	1,848,875	2,665,310	3,344,967	5,377,122
Net Margin	313,383	266,145	580,610	535,123
Operating Costs	77,410	76,081	159,656	141,183
Depreciation and amortization	39,433	31,109	78,727	58,187
Gain (loss) on sale of assets	(73)	11	(81)	(37)
Operating income	196,467	158,966	342,146	335,716
Equity in net earnings from investments	9,693	4,459	16,673	9,223
Investments in unconsolidated affiliates	485,381	485,960	485,381	485,960
Total Assets	8,139,588	7,363,417	8,139,588	7,363,417
Noncontrolling interests in consolidated subsidiaries	162,494	0	162,494	0
Capital expenditures	59,087	210,676	132,553	483,739
Natural Gas Liquids [Member] | Natural Gas Liquids for Regulated Segment [Member]
Segment disclosure [Abstract]
Total revenues	227,500	153,300	437,300	289,100
Net Margin	128,500	84,400	252,600	169,100
Operating income	73,600	34,500	138,500	79,600
Natural Gas Pipelines [Member]
Segment disclosure [Abstract]
Total revenues	80,112	81,985	163,661	186,778
Net Margin	74,107	75,471	143,230	168,960
Operating Costs	25,240	27,287	52,482	54,749
Depreciation and amortization	10,814	10,895	21,570	21,710
Gain (loss) on sale of assets	0	0	1	(83)
Operating income	38,053	37,289	69,179	92,418
Equity in net earnings from investments	15,425	15,877	35,127	39,286
Investments in unconsolidated affiliates	408,558	396,722	408,558	396,722
Total Assets	1,841,321	1,852,901	1,841,321	1,852,901
Noncontrolling interests in consolidated subsidiaries	0	0	0	0
Capital expenditures	15,613	8,710	25,205	15,337
Natural Gas Pipelines [Member] | Natural Gas Pipelines for Regulated Segment [Member]
Segment disclosure [Abstract]
Total revenues	64,100	68,300	133,400	149,600
Net Margin	57,100	59,500	118,000	128,100
Operating income	25,700	26,100	53,100	61,200
Other and Eliminations
Segment disclosure [Abstract]
Total revenues	(261,542)	(404,925)	(492,047)	(821,352)
Net Margin	(211)	(2,253)	(358)	(8,640)
Operating Costs	412	(2,109)	(127)	(9,314)
Depreciation and amortization	0	0	0	0
Gain (loss) on sale of assets	0	1	0	166
Operating income	(623)	(143)	(231)	840
Equity in net earnings from investments	0	0	0	0
Investments in unconsolidated affiliates	0	0	0	0
Total Assets	8,288	255,604	8,288	255,604
Noncontrolling interests in consolidated subsidiaries	0	15	0	15
Capital expenditures	5,226	1,819	9,903	2,239
Unaffiliated entity [Member]
Segment disclosure [Abstract]
Total revenues	2,127,507	3,065,735	3,932,266	6,174,512
Unaffiliated entity [Member] | Natural Gas Gathering and Processing [Member]
Segment disclosure [Abstract]
Total revenues	279,498	374,112	567,514	721,128
Unaffiliated entity [Member] | Natural Gas Liquids [Member]
Segment disclosure [Abstract]
Total revenues	1,769,580	2,612,336	3,204,393	5,282,991
Unaffiliated entity [Member] | Natural Gas Pipelines [Member]
Segment disclosure [Abstract]
Total revenues	78,429	79,287	160,359	170,393
Unaffiliated entity [Member] | Other and Eliminations
Segment disclosure [Abstract]
Total revenues	0	0	0	0
Affiliated Entity [Member]
Segment disclosure [Abstract]
Total revenues				53,526
Affiliated Entity [Member] | Natural Gas Gathering and Processing [Member]
Segment disclosure [Abstract]
Total revenues				41,214
Affiliated Entity [Member] | Natural Gas Liquids [Member]
Segment disclosure [Abstract]
Total revenues				0
Affiliated Entity [Member] | Natural Gas Pipelines [Member]
Segment disclosure [Abstract]
Total revenues				12,312
Affiliated Entity [Member] | Other and Eliminations
Segment disclosure [Abstract]
Total revenues				0
Operating Segments [Member]
Segment disclosure [Abstract]
Total revenues	0	0	0	0
Operating Segments [Member] | Natural Gas Gathering and Processing [Member]
Segment disclosure [Abstract]
Total revenues	180,564	349,253	348,171	723,148
Operating Segments [Member] | Natural Gas Liquids [Member]
Segment disclosure [Abstract]
Total revenues	79,295	52,974	140,574	94,131
Operating Segments [Member] | Natural Gas Liquids [Member] | Natural Gas Liquids for Regulated Segment [Member]
Segment disclosure [Abstract]
Total revenues	186,400	135,300	351,700	246,900
Operating Segments [Member] | Natural Gas Pipelines [Member]
Segment disclosure [Abstract]
Total revenues	1,683	2,698	3,302	4,073
Operating Segments [Member] | Other and Eliminations
Segment disclosure [Abstract]
Total revenues	$ (261,542)	$ (404,925)	$ (492,047)	$ (821,352)

SUPPLEMENTAL CONDENSED CONSOL52

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Commodity sales	$ 1,722,254	$ 2,715,109	$ 3,157,970	$ 5,521,838
Services	405,253	350,626	774,296	706,200
Total revenues	2,127,507	3,065,735	3,932,266	6,228,038
Cost of sales and fuel	1,603,093	2,571,402	2,946,957	5,224,071
Net margin	524,414	494,333	985,309	1,003,967
Operating expenses
Operations and maintenance	143,131	142,664	298,252	273,182
Depreciation and amortization	86,199	71,447	172,046	138,182
General taxes	23,481	17,981	46,519	37,646
Total operating expenses	252,811	232,092	516,817	449,010
Gain (loss) on sale of assets	122	(16)	116	(1)
Operating income	271,725	262,225	468,608	554,956
Equity in net earnings from investments	30,040	25,435	60,961	59,094
Allowance for equity funds used during construction	742	1,253	1,541	12,224
Interest expense, net	(86,492)	(73,008)	(167,201)	(141,284)
Income before income taxes	214,086	217,705	363,878	487,354
Income taxes	(2,476)	(3,194)	(5,236)	(7,375)
Net income	211,610	214,511	358,642	479,979
Less: Net income attributable to noncontrolling interest	1,840	77	3,278	153
Net income attributable to ONEOK Partners, L.P.	209,770	214,434	355,364	479,826
Parent [member]
Condensed Financial Statements, Captions [Line Items]
Commodity sales	0	0	0	0
Services	0	0	0	0
Total revenues	0	0	0	0
Cost of sales and fuel	0	0	0	0
Net margin	0	0	0	0
Operating expenses
Operations and maintenance	0	0	0	0
Depreciation and amortization	0	0	0	0
General taxes	0	0	0	0
Total operating expenses	0	0	0	0
Gain (loss) on sale of assets	0	0	0	0
Operating income	0	0	0	0
Equity in net earnings from investments	209,800	214,400	355,400	479,800
Allowance for equity funds used during construction	0	0	0	0
Other income (expense), net	95,300	83,100	182,100	165,800
Interest expense, net	(95,300)	(83,100)	(182,100)	(165,800)
Income before income taxes	209,800	214,400	355,400	479,800
Income taxes	0	0	0	0
Net income	209,800	214,400	355,400	479,800
Less: Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to ONEOK Partners, L.P.	209,800	214,400	355,400	479,800
Guarantor Subsidiary [member]
Condensed Financial Statements, Captions [Line Items]
Commodity sales	0	0	0	0
Services	0	0	0	0
Total revenues	0	0	0	0
Cost of sales and fuel	0	0	0	0
Net margin	0	0	0	0
Operating expenses
Operations and maintenance	0	0	0	0
Depreciation and amortization	0	0	0	0
General taxes	0	0	0	0
Total operating expenses	0	0	0	0
Gain (loss) on sale of assets	0	0	0	0
Operating income	0	0	0	0
Equity in net earnings from investments	209,800	214,400	355,400	479,800
Allowance for equity funds used during construction	0	0	0	0
Other income (expense), net	95,300	83,100	182,100	165,800
Interest expense, net	(95,300)	(83,100)	(182,100)	(165,800)
Income before income taxes	209,800	214,400	355,400	479,800
Income taxes	0	0	0	0
Net income	209,800	214,400	355,400	479,800
Less: Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to ONEOK Partners, L.P.	209,800	214,400	355,400	479,800
Combined Non-Guarantor Subsidiaries [member]
Condensed Financial Statements, Captions [Line Items]
Commodity sales	1,722,300	2,715,100	3,158,000	5,521,800
Services	405,300	350,600	774,300	706,200
Total revenues	2,127,600	3,065,700	3,932,300	6,228,000
Cost of sales and fuel	1,603,100	2,571,400	2,947,000	5,224,000
Net margin	524,500	494,300	985,300	1,004,000
Operating expenses
Operations and maintenance	143,100	142,700	298,300	273,200
Depreciation and amortization	86,200	71,400	172,000	138,200
General taxes	23,500	18,000	46,500	37,600
Total operating expenses	252,800	232,100	516,800	449,000
Gain (loss) on sale of assets	100	0	100	0
Operating income	271,800	262,200	468,600	555,000
Equity in net earnings from investments	14,600	9,600	25,800	19,800
Allowance for equity funds used during construction	700	1,300	1,500	12,200
Other income (expense), net	(1,900)	1,800	0	2,400
Interest expense, net	(86,500)	(73,000)	(167,200)	(141,300)
Income before income taxes	198,700	201,900	328,700	448,100
Income taxes	(2,500)	(3,200)	(5,300)	(7,400)
Net income	196,200	198,700	323,400	440,700
Less: Net income attributable to noncontrolling interest	1,800	100	3,200	200
Net income attributable to ONEOK Partners, L.P.	194,400	198,600	320,200	440,500
Consolidating Entries [member]
Condensed Financial Statements, Captions [Line Items]
Commodity sales	0	0	0	0
Services	0	0	0	0
Total revenues	0	0	0	0
Cost of sales and fuel	0	0	0	0
Net margin	0	0	0	0
Operating expenses
Operations and maintenance	0	0	0	0
Depreciation and amortization	0	0	0	0
General taxes	0	0	0	0
Total operating expenses	0	0	0	0
Gain (loss) on sale of assets	0	0	0	0
Operating income	0	0	0	0
Equity in net earnings from investments	(404,200)	(413,000)	(675,600)	(920,300)
Allowance for equity funds used during construction	0	0	0	0
Other income (expense), net	(190,600)	(166,200)	(364,200)	(331,600)
Interest expense, net	190,600	166,200	364,200	331,600
Income before income taxes	(404,200)	(413,000)	(675,600)	(920,300)
Income taxes	0	0	0	0
Net income	(404,200)	(413,000)	(675,600)	(920,300)
Less: Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to ONEOK Partners, L.P.	(404,200)	(413,000)	(675,600)	(920,300)
Total [Member]
Condensed Financial Statements, Captions [Line Items]
Commodity sales	1,722,300	2,715,100	3,158,000	5,521,800
Services	405,300	350,600	774,300	706,200
Total revenues	2,127,600	3,065,700	3,932,300	6,228,000
Cost of sales and fuel	1,603,100	2,571,400	2,947,000	5,224,000
Net margin	524,500	494,300	985,300	1,004,000
Operating expenses
Operations and maintenance	143,100	142,700	298,300	273,200
Depreciation and amortization	86,200	71,400	172,000	138,200
General taxes	23,500	18,000	46,500	37,600
Total operating expenses	252,800	232,100	516,800	449,000
Gain (loss) on sale of assets	100	0	100	0
Operating income	271,800	262,200	468,600	555,000
Equity in net earnings from investments	30,000	25,400	61,000	59,100
Allowance for equity funds used during construction	700	1,300	1,500	12,200
Other income (expense), net	(1,900)	1,800	0	2,400
Interest expense, net	(86,500)	(73,000)	(167,200)	(141,300)
Income before income taxes	214,100	217,700	363,900	487,400
Income taxes	(2,500)	(3,200)	(5,300)	(7,400)
Net income	211,600	214,500	358,600	480,000
Less: Net income attributable to noncontrolling interest	1,800	100	3,200	200
Net income attributable to ONEOK Partners, L.P.	209,800	214,400	355,400	479,800
Northern Border Pipeline [Member]
Operating expenses
Equity in net earnings from investments	$ 15,273	$ 15,877	$ 34,975	$ 39,286
Equity Method Investment, Ownership Percentage	50.00%		50.00%
Intermediate Partnership [Member]
Operating expenses
Equity Method Investment, Ownership Percentage	100.00%		100.00%

SUPPLEMENTAL CONDENSED CONSOL53

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Net income	$ 211,610	$ 214,511	$ 358,642	$ 479,979
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives	17,981	(32,515)	5,424	(88,970)
Realized (gains) losses on derivatives recognized in net income	(13,358)	7,834	(24,691)	36,842
Total other comprehensive income (loss)	4,623	(24,681)	(19,267)	(52,128)
Comprehensive income	216,233	189,830	339,375	427,851
Less: Comprehensive income attributable to noncontrolling interests	1,840	77	3,278	153
Comprehensive income attributable to ONEOK Partners, L.P.	214,393	189,753	336,097	427,698
Parent [member]
Condensed Financial Statements, Captions [Line Items]
Net income	209,800	214,400	355,400	479,800
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives	18,000	(32,500)	5,400	(89,000)
Realized (gains) losses on derivatives recognized in net income	(13,400)	7,800	(24,700)	36,900
Total other comprehensive income (loss)	4,600	(24,700)	(19,300)	(52,100)
Comprehensive income	214,400	189,700	336,100	427,700
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to ONEOK Partners, L.P.	214,400	189,700	336,100	427,700
Guarantor Subsidiary [member]
Condensed Financial Statements, Captions [Line Items]
Net income	209,800	214,400	355,400	479,800
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives	1,100	(6,100)	11,100	(41,900)
Realized (gains) losses on derivatives recognized in net income	(17,100)	5,200	(31,300)	31,600
Total other comprehensive income (loss)	(16,000)	(900)	(20,200)	(10,300)
Comprehensive income	193,800	213,500	335,200	469,500
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to ONEOK Partners, L.P.	193,800	213,500	335,200	469,500
Combined Non-Guarantor Subsidiaries [member]
Condensed Financial Statements, Captions [Line Items]
Net income	196,200	198,700	323,400	440,700
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives	1,100	(6,100)	11,100	(41,900)
Realized (gains) losses on derivatives recognized in net income	(17,100)	5,200	(31,300)	31,600
Total other comprehensive income (loss)	(16,000)	(900)	(20,200)	(10,300)
Comprehensive income	180,200	197,800	303,200	430,400
Less: Comprehensive income attributable to noncontrolling interests	1,800	100	3,200	200
Comprehensive income attributable to ONEOK Partners, L.P.	178,400	197,700	300,000	430,200
Consolidating Entries [member]
Condensed Financial Statements, Captions [Line Items]
Net income	(404,200)	(413,000)	(675,600)	(920,300)
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives	(2,200)	12,200	(22,200)	83,800
Realized (gains) losses on derivatives recognized in net income	34,200	(10,400)	62,600	(63,200)
Total other comprehensive income (loss)	32,000	1,800	40,400	20,600
Comprehensive income	(372,200)	(411,200)	(635,200)	(899,700)
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to ONEOK Partners, L.P.	(372,200)	(411,200)	(635,200)	(899,700)
Total [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	211,600	214,500	358,600	480,000
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives	18,000	(32,500)	5,400	(89,000)
Realized (gains) losses on derivatives recognized in net income	(13,400)	7,800	(24,700)	36,900
Total other comprehensive income (loss)	4,600	(24,700)	(19,300)	(52,100)
Comprehensive income	216,200	189,800	339,300	427,900
Less: Comprehensive income attributable to noncontrolling interests	1,800	100	3,200	200
Comprehensive income attributable to ONEOK Partners, L.P.	$ 214,400	$ 189,700	$ 336,100	$ 427,700

SUPPLEMENTAL CONDENSED CONSOL54

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 53,125	$ 42,530	$ 278,029	$ 134,530
Accounts receivable, net	683,674	735,830
Affiliate receivables	1,790	8,553
Natural gas and natural gas liquids in storage	150,137	134,134
Commodity imbalances	31,246	64,788
Materials and supplies	60,505	55,833
Other current assets	56,811	44,385
Total current assets	1,037,288	1,086,053
Property, plant and equipment
Property, plant and equipment	13,949,876	13,377,617
Accumulated depreciation and amortization	1,995,905	1,842,084
Net property, plant and equipment	11,953,971	11,535,533
Investments and other assets
Investments in unconsolidated affiliates	1,146,407	1,132,653	1,212,408
Goodwill and intangible assets	830,827	822,358
Other assets	28,160	23,803
Total investments and other assets	2,005,394	1,978,814
Total assets	14,996,653	14,600,400	13,748,515
Current liabilities
Current maturities of long-term debt	657,650	7,650
Notes payable	870,484	1,055,296
Accounts payable	687,321	874,692
Affiliate payables	28,304	36,106
Commodity imbalances	91,605	104,650
Accrued interest	102,196	91,990
Other current liabilities	127,067	165,672
Total current liabilities	2,564,627	2,336,056
Long-term debt, excluding current maturities	6,145,972	6,004,232
Deferred credits and other liabilities	$ 146,320	$ 141,337
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries	$ 5,973,175	$ 5,950,838
Noncontrolling interests in consolidated subsidiaries	166,559	167,937	4,508
Total equity	6,139,734	6,118,775
Total liabilities and equity	14,996,653	14,600,400
Parent [member]
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Affiliate receivables	0	0
Natural gas and natural gas liquids in storage	0	0
Commodity imbalances	0	0
Materials and supplies	0	0
Other current assets	700	1,900
Total current assets	700	1,900
Property, plant and equipment
Property, plant and equipment	0	0
Accumulated depreciation and amortization	0	0
Net property, plant and equipment	0	0
Investments and other assets
Investments in unconsolidated affiliates	3,989,800	4,248,000
Intercompany notes receivable	9,696,400	8,843,300
Goodwill and intangible assets	0	0
Other assets	7,000	2,100
Total investments and other assets	13,693,200	13,093,400
Total assets	13,693,900	13,095,300
Current liabilities
Current maturities of long-term debt	650,000	0
Notes payable	870,500	1,055,300
Accounts payable	0	0
Affiliate payables	0	0
Commodity imbalances	0	0
Accrued interest	102,200	92,000
Other current liabilities	0	44,800
Total current liabilities	1,622,700	1,192,100
Intercompany Debt	0	0
Long-term debt, excluding current maturities	6,098,000	5,952,400
Deferred credits and other liabilities	$ 0	$ 0
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries	$ 5,973,200	$ 5,950,800
Noncontrolling interests in consolidated subsidiaries	0	0
Total equity	5,973,200	5,950,800
Total liabilities and equity	13,693,900	13,095,300
Guarantor Subsidiary [member]
Current assets
Cash and cash equivalents	53,100	42,500	278,000	134,500
Accounts receivable, net	0	0
Affiliate receivables	0	0
Natural gas and natural gas liquids in storage	0	0
Commodity imbalances	0	0
Materials and supplies	0	0
Other current assets	0	0
Total current assets	53,100	42,500
Property, plant and equipment
Property, plant and equipment	0	0
Accumulated depreciation and amortization	0	0
Net property, plant and equipment	0	0
Investments and other assets
Investments in unconsolidated affiliates	5,756,100	5,469,800
Intercompany notes receivable	7,877,000	7,579,000
Goodwill and intangible assets	0	0
Other assets	0	0
Total investments and other assets	13,633,100	13,048,800
Total assets	13,686,200	13,091,300
Current liabilities
Current maturities of long-term debt	0	0
Notes payable	0	0
Accounts payable	0	0
Affiliate payables	0	0
Commodity imbalances	0	0
Accrued interest	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Intercompany Debt	9,696,400	8,843,300
Long-term debt, excluding current maturities	0	0
Deferred credits and other liabilities	$ 0	$ 0
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries	$ 3,989,800	$ 4,248,000
Noncontrolling interests in consolidated subsidiaries	0	0
Total equity	3,989,800	4,248,000
Total liabilities and equity	13,686,200	13,091,300
Combined Non-Guarantor Subsidiaries [member]
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	683,700	735,800
Affiliate receivables	1,800	8,600
Natural gas and natural gas liquids in storage	150,100	134,100
Commodity imbalances	31,200	64,800
Materials and supplies	60,500	55,800
Other current assets	56,200	42,500
Total current assets	983,500	1,041,600
Property, plant and equipment
Property, plant and equipment	13,949,900	13,377,600
Accumulated depreciation and amortization	1,995,900	1,842,100
Net property, plant and equipment	11,954,000	11,535,500
Investments and other assets
Investments in unconsolidated affiliates	772,200	746,100
Intercompany notes receivable	0	0
Goodwill and intangible assets	830,800	822,400
Other assets	21,200	21,800
Total investments and other assets	1,624,200	1,590,300
Total assets	14,561,700	14,167,400
Current liabilities
Current maturities of long-term debt	7,700	7,700
Notes payable	0	0
Accounts payable	687,300	874,700
Affiliate payables	28,300	36,100
Commodity imbalances	91,600	104,700
Accrued interest	0	0
Other current liabilities	127,000	120,800
Total current liabilities	941,900	1,144,000
Intercompany Debt	7,877,000	7,579,000
Long-term debt, excluding current maturities	48,000	51,900
Deferred credits and other liabilities	$ 146,300	$ 141,300
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries	$ 5,381,900	$ 5,083,300
Noncontrolling interests in consolidated subsidiaries	166,600	167,900
Total equity	5,548,500	5,251,200
Total liabilities and equity	14,561,700	14,167,400
Consolidating Entries [member]
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0
Affiliate receivables	0	0
Natural gas and natural gas liquids in storage	0	0
Commodity imbalances	0	0
Materials and supplies	0	0
Other current assets	0	0
Total current assets	0	0
Property, plant and equipment
Property, plant and equipment	0	0
Accumulated depreciation and amortization	0	0
Net property, plant and equipment	0	0
Investments and other assets
Investments in unconsolidated affiliates	(9,371,700)	(9,331,300)
Intercompany notes receivable	(17,573,400)	(16,422,300)
Goodwill and intangible assets	0	0
Other assets	0	0
Total investments and other assets	(26,945,100)	(25,753,600)
Total assets	(26,945,100)	(25,753,600)
Current liabilities
Current maturities of long-term debt	0	0
Notes payable	0	0
Accounts payable	0	0
Affiliate payables	0	0
Commodity imbalances	0	0
Accrued interest	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Intercompany Debt	(17,573,400)	(16,422,300)
Long-term debt, excluding current maturities	0	0
Deferred credits and other liabilities	$ 0	$ 0
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries	$ (9,371,700)	$ (9,331,300)
Noncontrolling interests in consolidated subsidiaries	0	0
Total equity	(9,371,700)	(9,331,300)
Total liabilities and equity	(26,945,100)	(25,753,600)
Total [Member]
Current assets
Cash and cash equivalents	53,100	42,500	$ 278,000	$ 134,500
Accounts receivable, net	683,700	735,800
Affiliate receivables	1,800	8,600
Natural gas and natural gas liquids in storage	150,100	134,100
Commodity imbalances	31,200	64,800
Materials and supplies	60,500	55,800
Other current assets	56,900	44,400
Total current assets	1,037,300	1,086,000
Property, plant and equipment
Property, plant and equipment	13,949,900	13,377,600
Accumulated depreciation and amortization	1,995,900	1,842,100
Net property, plant and equipment	11,954,000	11,535,500
Investments and other assets
Investments in unconsolidated affiliates	1,146,400	1,132,600
Intercompany notes receivable	0	0
Goodwill and intangible assets	830,800	822,400
Other assets	28,200	23,900
Total investments and other assets	2,005,400	1,978,900
Total assets	14,996,700	14,600,400
Current liabilities
Current maturities of long-term debt	657,700	7,700
Notes payable	870,500	1,055,300
Accounts payable	687,300	874,700
Affiliate payables	28,300	36,100
Commodity imbalances	91,600	104,700
Accrued interest	102,200	92,000
Other current liabilities	127,000	165,600
Total current liabilities	2,564,600	2,336,100
Intercompany Debt	0	0
Long-term debt, excluding current maturities	6,146,000	6,004,300
Deferred credits and other liabilities	$ 146,300	$ 141,300
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries	$ 5,973,200	$ 5,950,800
Noncontrolling interests in consolidated subsidiaries	166,600	167,900
Total equity	6,139,800	6,118,700
Total liabilities and equity	$ 14,996,700	$ 14,600,400

SUPPLEMENTAL CONDENSED CONSOL55

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating activities
Cash provided by operating activities			$ 380,267	$ 534,078
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	$ (285,360)	$ (389,413)	(628,396)	(792,414)
Cash paid for acquisitions			0	(14,000)
Contributions to unconsolidated affiliates			(33,222)	(1,063)
Distributions received from unconsolidated affiliates in excess of cumulative earnings			18,814	16,449
Proceeds from sale of assets			691	319
Other			(12,607)	0
Cash provided by (used in) investing activities			(654,720)	(790,709)
Financing activities
Cash distributions paid to general and limited partners			(593,435)	(493,049)
Cash distributions paid to noncontrolling interests			(4,694)	(181)
Borrowing (repayment) of notes payable, net			(184,812)	0
Issuance of long-term debt, net of discounts			798,896	0
Debt financing costs			(7,850)	0
Repayment of long-term debt			(3,825)	(3,825)
Issuance of common units, net of issuance costs			275,098	878,765
Contribution from general partner			5,670	18,420
Cash provided by (used in) financing activities			285,048	400,130
Change in cash and cash equivalents			10,595	143,499
Cash and cash equivalents at beginning of period			42,530	134,530
Cash and cash equivalents at end of period	53,125	278,029	53,125	278,029
Parent [member]
Operating activities
Cash provided by operating activities			550,200	505,300
Investing activities
Capital expenditures (less allowance for equity funds used during construction)			0	0
Cash paid for acquisitions				0
Contributions to unconsolidated affiliates			0	0
Distributions received from unconsolidated affiliates in excess of cumulative earnings			0	0
Proceeds from sale of assets			0	0
Other			0
Cash provided by (used in) investing activities			0	0
Financing activities
Cash distributions paid to general and limited partners			(593,500)	(493,100)
Cash distributions paid to noncontrolling interests			0	0
Borrowing (repayment) of notes payable, net			(184,800)	0
Issuance of long-term debt, net of discounts			798,900
Debt financing costs			(7,900)
Intercompany borrowings (advances), net			(843,700)	(909,400)
Repayment of long-term debt			0	0
Issuance of common units, net of issuance costs			275,100	878,800
Contribution from general partner			5,700	18,400
Cash provided by (used in) financing activities			(550,200)	(505,300)
Change in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of period			0	0
Cash and cash equivalents at end of period	0	0	0	0
Guarantor Subsidiary [member]
Operating activities
Cash provided by operating activities			35,000	39,300
Investing activities
Capital expenditures (less allowance for equity funds used during construction)			0	0
Cash paid for acquisitions				0
Contributions to unconsolidated affiliates			0	0
Distributions received from unconsolidated affiliates in excess of cumulative earnings			12,400	8,100
Proceeds from sale of assets			0	0
Other			0
Cash provided by (used in) investing activities			12,400	8,100
Financing activities
Cash distributions paid to general and limited partners			(593,500)	(493,100)
Cash distributions paid to noncontrolling interests			0	0
Borrowing (repayment) of notes payable, net			0	0
Issuance of long-term debt, net of discounts			0
Debt financing costs			0
Intercompany borrowings (advances), net			556,700	589,200
Repayment of long-term debt			0	0
Issuance of common units, net of issuance costs			0	0
Contribution from general partner			0	0
Cash provided by (used in) financing activities			(36,800)	96,100
Change in cash and cash equivalents			10,600	143,500
Cash and cash equivalents at beginning of period			42,500	134,500
Cash and cash equivalents at end of period	53,100	278,000	53,100	278,000
Combined Non-Guarantor Subsidiaries [member]
Operating activities
Cash provided by operating activities			388,600	482,600
Investing activities
Capital expenditures (less allowance for equity funds used during construction)			(628,400)	(792,400)
Cash paid for acquisitions				(14,000)
Contributions to unconsolidated affiliates			(33,200)	(1,100)
Distributions received from unconsolidated affiliates in excess of cumulative earnings			6,400	8,400
Proceeds from sale of assets			700	300
Other			(12,600)
Cash provided by (used in) investing activities			(667,100)	(798,800)
Financing activities
Cash distributions paid to general and limited partners			0	0
Cash distributions paid to noncontrolling interests			(4,700)	(200)
Borrowing (repayment) of notes payable, net			0	0
Issuance of long-term debt, net of discounts			0
Debt financing costs			0
Intercompany borrowings (advances), net			287,000	320,200
Repayment of long-term debt			(3,800)	(3,800)
Issuance of common units, net of issuance costs			0	0
Contribution from general partner			0	0
Cash provided by (used in) financing activities			278,500	316,200
Change in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of period			0	0
Cash and cash equivalents at end of period	0	0	0	0
Consolidating Entries [member]
Operating activities
Cash provided by operating activities			(593,500)	(493,100)
Investing activities
Capital expenditures (less allowance for equity funds used during construction)			0	0
Cash paid for acquisitions				0
Contributions to unconsolidated affiliates			0	0
Distributions received from unconsolidated affiliates in excess of cumulative earnings			0	0
Proceeds from sale of assets			0	0
Other			0
Cash provided by (used in) investing activities			0	0
Financing activities
Cash distributions paid to general and limited partners			593,500	493,100
Cash distributions paid to noncontrolling interests			0	0
Borrowing (repayment) of notes payable, net			0	0
Issuance of long-term debt, net of discounts			0
Debt financing costs			0
Intercompany borrowings (advances), net			0	0
Repayment of long-term debt			0	0
Issuance of common units, net of issuance costs			0	0
Contribution from general partner			0	0
Cash provided by (used in) financing activities			593,500	493,100
Change in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of period			0	0
Cash and cash equivalents at end of period	0	0	0	0
Total [Member]
Operating activities
Cash provided by operating activities			380,300	534,100
Investing activities
Capital expenditures (less allowance for equity funds used during construction)			(628,400)	(792,400)
Cash paid for acquisitions				(14,000)
Contributions to unconsolidated affiliates			(33,200)	(1,100)
Distributions received from unconsolidated affiliates in excess of cumulative earnings			18,800	16,500
Proceeds from sale of assets			700	300
Other			(12,600)
Cash provided by (used in) investing activities			(654,700)	(790,700)
Financing activities
Cash distributions paid to general and limited partners			(593,500)	(493,100)
Cash distributions paid to noncontrolling interests			(4,700)	(200)
Borrowing (repayment) of notes payable, net			(184,800)	0
Issuance of long-term debt, net of discounts			798,900
Debt financing costs			(7,900)
Intercompany borrowings (advances), net			0	0
Repayment of long-term debt			(3,800)	(3,800)
Issuance of common units, net of issuance costs			275,100	878,800
Contribution from general partner			5,700	18,400
Cash provided by (used in) financing activities			285,000	400,100
Change in cash and cash equivalents			10,600	143,500
Cash and cash equivalents at beginning of period			42,500	134,500
Cash and cash equivalents at end of period	$ 53,100	$ 278,000	$ 53,100	$ 278,000