ONEOK Partners (OKS) 10-K 25 Feb 15 2014 FY Annual report Financial data

Document_And_Entity_Informatio

Document And Entity Information (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 17, 2015	Jun. 30, 2014
Document Information [Line Items]
Entity Registrant Name	ONEOK Partners LP
Entity Central Index Key	909281
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$9.10
Entity Common Stock, Shares Outstanding		180,826,973
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues [Abstract]
Commodity Sales	$10,724,981	$10,549,157	$9,010,151
Services	1,466,684	1,320,116	1,172,000
Total revenues	12,191,665	11,869,273	10,182,151
Cost of sales and fuel	10,088,548	10,222,213	8,540,319
Net margin	2,103,117	1,647,060	1,641,832
Operating expenses
Operations and maintenance	599,076	464,633	433,063
Depreciation and amortization	291,236	236,743	203,101
General taxes	70,581	56,880	49,477
Total operating expenses	960,893	758,256	685,641
Gain (loss) on sale of assets	6,599	11,881	6,736
Operating income	1,148,823	900,685	962,927
Equity earnings from investments (Note M)	41,003	110,517	123,024
Allowance for equity funds used during construction	14,937	30,522	13,648
Other income	5,447	12,870	7,577
Other expense	-4,299	-3,039	-2,625
Interest expense (net of capitalized interest of $54,813, $56,506 and $40,482, respectively)	-281,908	-236,714	-206,018
Income before income taxes	924,003	814,841	898,533
Income taxes (Note L)	-12,668	-10,858	-10,105
Net income	911,335	803,983	888,428
Less: Net income attributable to noncontrolling interests	1,037	357	438
Net income attributable to ONEOK Partners, L.P.	910,298	803,626	887,990
Limited partners' interest in net income:
Net income attributable to ONEOK Partners, L.P.	910,298	803,626	887,990
General partner's interest in net income	-344,241	-275,539	-227,855
Limited partners' interest in net income	$566,057	$528,087	$660,135
Limited partners' net income per unit, basic and diluted (Note K)	$2.33	$2.35	$3.04
Number of units used in computation (thousands)	243,306	224,658	217,134

CONSOLIDATED_STATEMENTS_OF_INC1

CONSOLIDATED STATEMENTS OF INCOME (Parenthetical) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Interest Costs, Capitalized During Period	$54,813	$56,506	$40,482
Net Income (Loss), Net of Tax, Per Outstanding Limited Partnership Unit, Diluted	$2.33	$2.35	$3.04

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$264,036	$167,320	$214,511	$265,468	$228,444	$216,400	$202,454	$156,685	$911,335	$803,983	$888,428
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives									-64,639	32,141	10,295
Realized (gains) losses on derivatives recognized in net income									31,653	8,344	-58,529
Total other comprehensive income (loss)									-32,986	40,485	-48,234
Comprehensive income									878,349	844,468	840,194
Less: Comprehensive income attributable to noncontrolling interests									1,037	357	438
Comprehensive income attributable to ONEOK Partners, L.P.									$877,312	$844,111	$839,756

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets
Cash and cash equivalents	$42,530	$134,530
Accounts receivable, net	735,830	1,103,130
Affiliate receivables	8,553	9,185
Natural Gas and natural gas liquids in storage	134,134	188,286
Commodity imbalances	64,788	80,481
Materials and Supplies	55,833	54,112
Other current assets	44,385	13,379
Total current assets	1,086,053	1,583,103
Property, plant and equipment
Property, plant and equipment	13,377,617	10,755,048
Accumulated depreciation and amortization	1,842,084	1,652,648
Net property, plant and equipment (Note E)	11,535,533	9,102,400
Investments and other assets
Investments in unconsolidated affiliates (Note M)	1,132,653	1,229,838
Goodwill and intangible assets (Note F)	822,358	832,180
Other assets	57,950	115,087
Total investments and other assets	2,012,961	2,177,105
Total assets	14,634,547	12,862,608
Current liabilities
Current maturities of long-term debt (Note H)	7,650	7,650
Notes payable (Note G)	1,055,296	0
Accounts payable	874,692	1,255,411
Affiliate payables	36,106	47,458
Commodity imbalances	104,650	213,577
Accrued interest	91,990	92,711
Other current liabilities	165,672	89,211
Total current liabilities	2,336,056	1,706,018
Long-term debt, excluding current maturities (Note H)	6,038,379	6,044,867
Deferred credits and other liabilities	141,337	113,027
Commitments and contingencies (Note O)
ONEOK Partners, L.P. partners' equity (Note I):
General partner	211,914	170,561
Common units: 180,826,973 and 159,007,854 units issued and outstanding at December 31, 2014 and December 31, 2013	4,456,372	3,459,920
Class B units: 72,988,252 units issued and outstanding at December 31, 2014 and December 31, 2013	1,374,375	1,422,516
Accumulated other comprehensive loss (Note J)	-91,823	-58,837
Total ONEOK Partners, L.P. partners' equity	5,950,838	4,994,160
Noncontrolling interests in consolidated subsidiaries	167,937	4,536
Total equity	6,118,775	4,998,696
Total liabilities and equity	$14,634,547	$12,862,608

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical)	Dec. 31, 2014	Dec. 31, 2013
ONEOK Partners, L.P. partners equity:
Common units issued (in shares)	180,826,973	159,007,854
Common units outstanding (in shares)	180,826,973	159,007,854
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_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net income	$911,335	$803,983	$888,428
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	291,236	236,743	203,101
Allowance for equity funds used during construction	-14,937	-30,522	-13,648
Loss (gain) on sale of assets	-6,599	-11,881	-6,736
Deferred income taxes	10,832	5,444	6,815
Equity earnings from investments	-41,003	-110,517	-123,024
Distributions received from unconsolidated affiliates	117,912	106,364	120,442
Changes in assets and liabilities, net of acquisition:
Accounts receivable	373,459	-184,271	8,201
Affiliate receivables	632	6,907	-11,960
Natural Gas and natural gas liquids in storage	54,152	47,550	-33,650
Accounts payable	-351,470	187,253	-45,014
Affiliate payables	-11,352	-28,252	34,614
Commodity imbalances, net	-93,234	-50,373	43,811
Accrued Interest	-721	15,977	6,350
Other assets and liabilities, net	69,578	13,326	-131,677
Cash provided by operating activities	1,309,820	1,007,731	946,053
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	-1,745,990	-1,939,326	-1,560,513
Cash paid for acquisition, net of cash received	-814,934	-394,889	0
Contributions to unconsolidated affiliates	-1,063	-35,308	-30,768
Distributions received from unconsolidated affiliates	21,107	31,134	35,299
Proceeds from sale of assets	7,817	12,290	10,778
Cash used in investing activities	-2,533,063	-2,326,099	-1,545,204
Financing activities
Cash distributions: General and limited partners	-1,052,245	-909,713	-760,912
Cash distributions: Noncontrolling interests	-549	-588	-783
Borrowing (repayment) of notes payable, net	1,055,296	0	0
Issuance of long-term debt, net of discounts	0	1,247,822	1,295,036
Long-term debt financing costs	0	-10,246	-9,641
Repayment of long-term debt	-7,650	-7,650	-361,062
Issuance of common units, net of issuance costs	1,113,139	583,929	919,427
Contribution from general partner	23,252	12,270	19,069
Cash provided by financing activities	1,131,243	915,824	1,101,134
Change in cash and cash equivalents	-92,000	-402,544	501,983
Cash and cash equivalents at beginning of period	134,530	537,074	35,091
Cash and cash equivalents at end of period	42,530	134,530	537,074
Supplemental cash flow information:
Cash paid for interest, net of amounts capitalized	271,314	203,072	317,044
Cash paid for income taxes	$1,336	$3,435	$7,542

CONSOLIDATED_STATEMENT_OF_CHAN

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (USD $)	Total	Noncontrolling Interests in Consolidated Subsidiaries [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	General Partner [Member]	Class B Units [Member]	Common Units [Member]
In Thousands, except Share data
Partners capital account beginning balance at Dec. 31, 2011	$3,446,512	$5,112	($51,088)	$106,936	$1,426,115	$1,959,437
Partners capital account, units, beginning balance at Dec. 31, 2011					72,988,252	130,827,354
Net income	888,428	438	0	227,855	223,425	436,710
Other comprehensive income (loss)	-48,234	0	-48,234	0	0	0
Issuance of common units (in units) (Note I)					0	16,000,000
Issuance of common units (Note I)	919,427	0	0	0	0	919,427
Contribution from general partner (Note I)	19,069	0	0	19,069	0	0
Distributions paid (Note I)	-761,695	-783	0	-201,347	-189,042	-370,523
Partners capital account ending balance at Dec. 31, 2012	4,463,507	4,767	-99,322	152,513	1,460,498	2,945,051
Partners capital account, units, ending balance at Dec. 31, 2012					72,988,252	146,827,354
Net income	803,983	357	0	275,539	171,494	356,593
Other comprehensive income (loss)	40,485	0	40,485	0	0	0
Issuance of common units (in units) (Note I)					0	12,180,500
Issuance of common units (Note I)	588,656	0	0	0	0	588,656
Contribution from general partner (Note I)	12,366	0	0	12,366	0	0
Distributions paid (Note I)	-910,301	-588	0	-269,857	-209,476	-430,380
Partners capital account ending balance at Dec. 31, 2013	4,998,696	4,536	-58,837	170,561	1,422,516	3,459,920
Partners capital account, units, ending balance at Dec. 31, 2013					72,988,252	159,007,854
Net income	911,335	1,037	0	344,241	171,554	394,503
Other comprehensive income (loss)	-32,986	0	-32,986	0	0	0
Issuance of common units (in units) (Note I)					0	21,819,119
Issuance of common units (Note I)	1,108,456	0	0	0	0	1,108,456
Contribution from general partner (Note I)	23,155	0	0	23,155	0	0
Distributions paid (Note I)	-1,052,794	-549	0	-326,043	-219,695	-506,507
West Texas LPG noncontrolling interest (Note B)	162,913	162,913	0	0	0	0
Partners capital account ending balance at Dec. 31, 2014	$6,118,775	$167,937	($91,823)	$211,914	$1,374,375	$4,456,372
Partners capital account, units, ending balance at Dec. 31, 2014					72,988,252	180,826,973

SUMMARY_OF_SIGNIFICANT_ACCOUNT

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	A.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Organization and Nature of Operations - ONEOK Partners, L.P. is a publicly traded master limited partnership, organized under the laws of the state of Delaware, that was formed in 1993.  Our equity consists of a 2 percent general partner interest and a 98 percent limited partner interest. Our limited partner interests are represented by our common units, which are listed on the NYSE under the trading symbol “OKS,” and our Class B limited partner units.  We are managed under the direction of the Board of Directors of our sole general partner, ONEOK Partners GP.  ONEOK Partners GP is a wholly owned subsidiary of ONEOK.  ONEOK and its subsidiaries owned a 37.8 percent aggregate equity interest in us at December 31, 2014.
	Our operations include gathering and processing of natural gas produced from crude oil and natural gas wells.  We gather and process natural gas in the Mid-Continent region, which includes the NGL-rich Cana-Woodford Shale, Woodford Shale, Stack, SCOOP, Springer Shale and the Mississippian Lime formation of Oklahoma and Kansas, and the Hugoton and Central Kansas Uplift Basins of Kansas.  We also gather and/or process natural gas in two producing basins in the Rocky Mountain region: the Williston Basin, which spans portions of Montana and North Dakota and includes the oil-producing, NGL-rich Bakken Shale and Three Forks formations; and the Powder River Basin of Wyoming, which includes the NGL-rich Frontier, Turner, Sussex and Niobrara Shale formations. The natural gas we gather from wells that supply our Sage Creek plant contains NGL-rich natural gas from the Niobrara Shale area of the Powder River Basin. Some of the natural gas we gather from the Powder River Basin of Wyoming is coal-bed methane, or dry natural gas, that does not require processing or NGL extraction in order to be marketable; dry natural gas is gathered, compressed and delivered into a downstream pipeline or marketed for a fee.
	Our natural gas liquids assets consist of facilities that gather, fractionate and treat NGLs and store NGL products primarily in Oklahoma, Kansas, Texas, New Mexico and the Rocky Mountain region where we provide nondiscretionary services to producers of NGLs. We own or have an ownership interest in FERC-regulated natural gas liquids gathering and distribution pipelines in Oklahoma, Kansas, Texas, New Mexico, Montana, North Dakota, Wyoming and Colorado, and terminal and storage facilities in Missouri, Nebraska, Iowa and Illinois.  We also own FERC-regulated natural gas liquids distribution and refined petroleum products pipelines in Kansas, Missouri, Nebraska, Iowa, Illinois and Indiana that connect our Mid-Continent assets with Midwest markets, including Chicago, Illinois.  We own and operate truck- and rail-loading and -unloading facilities that interconnect with our NGL fractionation and pipeline assets.
	Our FERC-regulated interstate natural gas pipeline assets transport natural gas through gas pipelines in North Dakota, Minnesota, Wisconsin, Illinois, Indiana, Kentucky, Tennessee, Oklahoma, Texas and New Mexico.  Our interstate pipeline companies include Midwestern Gas Transmission, Viking Gas Transmission, Guardian Pipeline, OkTex Pipeline and Northern Border Pipeline of which we have a 50 percent interest.
	Our intrastate natural gas pipeline assets in Oklahoma transport natural gas through the state and have access to the major natural gas producing formations, including the Cana-Woodford Shale, Woodford Shale, Springer Shale, Granite Wash, Stack, SCOOP and Mississippian Lime areas.  We also have access to the major natural gas producing areas, including the Mississippian Lime formation, in south central Kansas.  In Texas, our intrastate natural gas pipelines are connected to the major natural gas producing areas in the Texas panhandle, including the Granite Wash formation and Delaware and Cline producing formations in the Permian Basin, and transport natural gas throughout the western portion of Texas, including the Waha Hub where other pipelines may be accessed for transportation to western markets, the Houston Ship Channel market to the east and the Mid-Continent market to the north.
	We own underground natural gas storage facilities in Oklahoma and Texas that are connected to our intrastate natural gas pipeline assets. We also have underground natural gas storage facilities in Kansas.
	Consolidation - Our consolidated financial statements include the accounts of ONEOK Partners and our subsidiaries over which we have control or are the primary beneficiary. All significant intercompany balances and transactions have been eliminated in consolidation.
	Investments in unconsolidated affiliates are accounted for using the equity method if we have the ability to exercise significant influence over operating and financial policies of our investee. Under this method, an investment is carried at its acquisition cost and adjusted each period for contributions made, distributions received and our share of the investee’s comprehensive income. For the investments we account for under the equity method, the premium or excess cost over underlying fair value of net assets is referred to as equity method goodwill. Impairment of equity investments is recorded when the impairments are other than temporary. These amounts are recorded as investments in unconsolidated affiliates on our accompanying Consolidated Balance Sheets.  See Note M for disclosures of our unconsolidated affiliates.
	Distributions paid to us from our unconsolidated affiliates are classified as operating activities on our Consolidated Statements of Cash Flows until the cumulative distributions exceed our proportionate share of income from the unconsolidated affiliate since the date of our initial investment.  The amount of cumulative distributions paid to us that exceeds our cumulative proportionate share of income in each period represents a return of investment and is classified as an investing activity on our Consolidated Statements of Cash Flows.
	Use of Estimates - The preparation of our consolidated financial statements and related disclosures in accordance with GAAP requires us to make estimates and assumptions with respect to values or conditions that cannot be known with certainty that affect the reported amount of assets and liabilities, and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements.  These estimates and assumptions also affect the reported amounts of revenue and expenses during the reporting period.  Items that may be estimated include, but are not limited to, the economic useful life of assets, fair value of assets, liabilities and equity method investments, provisions for uncollectible accounts receivable, unbilled revenues and cost of goods sold, expenses for services received but for which no invoice has been received, the results of litigation and various other recorded or disclosed amounts.
	We evaluate these estimates on an ongoing basis using historical experience, consultation with experts and other methods we consider reasonable based on the particular circumstances.  Nevertheless, actual results may differ significantly from the estimates.  Any effects on our financial position or results of operations from revisions to these estimates are recorded in the period when the facts that give rise to the revision become known.
	Fair Value Measurements - 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 groups 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 and LIBOR and other liquid money-market instrument rates. We also utilize internally developed basis curves that incorporate observable and unobservable market data. 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 internally developed basis curves that incorporate observable and unobservable market data, NGL price curves from broker quotes, 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 is not 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.
	See Note C for discussion of our fair value measurements.
	Cash and Cash Equivalents - Cash equivalents consist of highly liquid investments, which are readily convertible into cash and have original maturities of three months or less.
	Revenue Recognition - Our reportable segments recognize revenue when services are rendered or product is delivered.  Our Natural Gas Gathering and Processing segment records revenues when gas is processed in or transported through our facilities. Our Natural Gas Liquids segment records revenues based upon contracted services and actual volumes exchanged or stored under service agreements in the period services are provided.  A portion of our revenues for our Natural Gas Liquids segment and Natural Gas Pipelines segment are recognized based upon contracted capacity and contracted volumes transported and stored under service agreements in the period services are provided.
	Accounts Receivable - Accounts receivable represent valid claims against nonaffiliated customers for products sold or services rendered, net of allowances for doubtful accounts.  We assess the creditworthiness of our counterparties on an ongoing basis and require security, including prepayments and other forms of collateral, when appropriate.  Outstanding customer receivables are reviewed regularly for possible nonpayment indicators, and allowances for doubtful accounts are recorded based upon management’s estimate of collectability at each balance sheet date.  At December 31, 2014 and 2013, our allowance for doubtful accounts was not material.
	Inventory - The values of current natural gas and NGLs in storage are determined using the lower of weighted-average cost or market method.  Noncurrent natural gas and NGLs are classified as property and valued at cost.  Materials and supplies are valued at average cost.
	Commodity Imbalances - Commodity imbalances represent amounts payable or receivable for NGL exchange contracts and natural gas pipeline imbalances and are valued at market prices.  Under the majority of our NGL exchange agreements, we physically receive volumes of unfractionated NGLs, including the risk of loss and legal title to such volumes, from the exchange counterparty.  In turn, we deliver NGL products back to the customer and charge them gathering and fractionation fees. To the extent that the volumes we receive under such agreements differ from those we deliver, we record a net exchange receivable or payable position with the counterparties.  These net exchange receivables and payables are settled with movements of NGL products rather than with cash.  Natural gas pipeline imbalances are settled in cash or in-kind, subject to the terms of the pipelines’ tariffs or by agreement.
	Derivatives and Risk Management - We utilize derivatives to reduce our market risk exposure to commodity price and interest-rate fluctuations and to achieve more predictable cash flows.  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	-	Fair value not recorded	-	Change in fair value not recognized in earnings
	normal sales
	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	-	Effective portion of the gain or loss on the
			derivative instrument is reported initially as a		derivative instrument is reclassified out of
			component of accumulated other		accumulated other comprehensive income (loss)
			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	-	Change in fair value of the hedged item is
			recorded as an adjustment to book value		recognized in earnings
	To reduce our exposure to fluctuations in natural gas, NGLs and condensate prices, we periodically enter into futures, forward sales 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 cash flow. We formally document all relationships between hedging instruments and hedged items, as well as risk-management objectives, 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.
	See Notes C and D for more discussion of our fair value measurements and risk management and hedging activities using derivatives.
	Property, Plant and Equipment - Our properties are stated at cost, including AFUDC.  Generally, the cost of regulated property retired or sold, plus removal costs, less salvage, is charged to accumulated depreciation.  Gains and losses from sales or transfers of nonregulated properties or an entire operating unit or system of our regulated properties are recognized in income. Maintenance and repairs are charged directly to expense.
	The interest portion of AFUDC represents the cost of borrowed funds used to finance construction activities.  We capitalize interest costs during the construction or upgrade of qualifying assets.  Capitalized interest is recorded as a reduction to interest expense. The equity portion of AFUDC represents the capitalization of the estimated average cost of equity used during the construction of major projects and is recorded in the cost of our regulated properties and as a credit to the allowance for equity funds used during construction.
	Our properties are depreciated using the straight-line method over their estimated useful lives.  Generally, we apply composite depreciation rates to functional groups of property having similar economic circumstances.  We periodically conduct depreciation studies to assess the economic lives of our assets.  For our regulated assets, these depreciation studies are completed as a part of our rate proceedings or tariff filings, and the changes in economic lives, if applicable, are implemented prospectively when the new rates are billed.  For our nonregulated assets, if it is determined that the estimated economic life changes, the changes are made prospectively.  Changes in the estimated economic lives of our property, plant and equipment could have a material effect on our financial position or results of operations.
	Property, plant and equipment on our Consolidated Balance Sheets includes construction work in process for capital projects that have not yet been placed in service and therefore are not being depreciated.  Assets are transferred out of construction work in process when they are substantially complete and ready for their intended use.
	See Note E for disclosures of our property, plant and equipment.
	Impairment of Goodwill and Long-Lived Assets, Including Intangible Assets - We assess our goodwill for impairment at least annually as of July 1.  Our goodwill impairment analysis performed as of July 1, 2014, did not result in an impairment charge nor did our analysis reflect any reporting units at risk, and subsequent to that date, no event has occurred indicating that the implied fair value of each of our reporting units (including its inherent goodwill) is less than the carrying value of its net assets. There were also no impairment charges resulting from our 2013 or 2012 impairment tests.
	As part of our impairment test, we first assess qualitative factors (including macroeconomic conditions, industry and market considerations, cost factors and overall financial performance) to determine whether it is more likely than not that the fair value of each of our reporting units is less than its carrying amount. If further testing is necessary, we perform a two-step impairment test for goodwill. In the first step, an initial assessment is made by comparing the fair value of a reporting unit with its book value, including goodwill.  If the fair value is less than the book value, an impairment is indicated, and we must perform a second test to measure the amount of the impairment. In the second test, we calculate the implied fair value of the goodwill by deducting the fair value of all tangible and intangible net assets of the reporting unit from the fair value determined in step one of the assessment. If the carrying value of the goodwill exceeds the implied fair value of the goodwill, we will record an impairment charge.
	To estimate the fair value of our reporting units, we use two generally accepted valuation approaches, an income approach and a market approach, using assumptions consistent with a market participant’s perspective.  Under the income approach, we use anticipated cash flows over a period of years plus a terminal value and discount these amounts to their present value using appropriate discount rates.  Under the market approach, we apply EBITDA multiples to forecasted EBITDA.  The multiples used are consistent with historical asset transactions.  The forecasted cash flows are based on average forecasted cash flows for a reporting unit over a period of years.
	We assess our long-lived assets, including intangible assets with finite useful lives, for impairment whenever events or changes in circumstances indicate that an asset’s carrying amount may not be recoverable.  An impairment is indicated if the carrying amount of a long-lived asset exceeds the sum of the undiscounted future cash flows expected to result from the use and eventual disposition of the asset.  If an impairment is indicated, we record an impairment loss equal to the difference between the carrying value and the fair value of the long-lived asset.  We determined that there were no asset impairments in 2014, 2013 or 2012.
	For the investments we account for under the equity method, the impairment test considers whether the fair value of the equity investment as a whole, not the underlying net assets, has declined and whether that decline is other than temporary.  Therefore, we periodically reevaluate the amount at which we carry our equity method investments to determine whether current events or circumstances warrant adjustments to our carrying value.
	See Notes E, F and M for our long-lived assets, goodwill and intangible assets and unconsolidated affiliates disclosures.
	Regulation - Our intrastate natural gas transmission pipelines are subject to the rate regulation and accounting requirements of the OCC, KCC, RRC and various municipalities in Texas.  Our interstate natural gas and natural gas liquids pipelines are subject to regulation by the FERC.  In Kansas and Texas, natural gas storage may be regulated by the state and the FERC for certain types of services.  Accordingly, portions of our Natural Gas Liquids and Natural Gas Pipelines segments follow the accounting and reporting guidance for regulated operations.  During the rate-making process for certain of our assets, regulatory authorities set the framework for what we can charge customers for our services and establish the manner that our costs are accounted for, including allowing us to defer recognition of certain costs and permitting recovery of the amounts through rates over time as opposed to expensing such costs as incurred. Certain examples of types of regulatory guidance include costs for fuel and losses, acquisition costs, contributions in aid of construction, charges for depreciation, and gains or losses on disposition of assets.  This allows us to stabilize rates over time rather than passing such costs on to the customer for immediate recovery.  Actions by regulatory authorities could have an effect on the amount recovered from rate payers.  Any difference in the amount recoverable and the amount deferred is recorded as income or expense at the time of the regulatory action.  A write-off of regulatory assets and costs not recovered may be required if all or a portion of the regulated operations have rates that are no longer:
	•	established by independent, third-party regulators;
	•	designed to recover the specific entity’s costs of providing regulated services; and
•	set at levels that will recover our costs when considering the demand and competition for our services.
At December 31, 2014 and 2013, we recorded regulatory assets of approximately $6.1 million and $6.8 million, respectively, which are currently being recovered and are expected to be recovered from our customers.  Regulatory assets are being recovered as a result of approved rate proceedings over varying time periods up to 40 years.  These assets are reflected in other assets on our Consolidated Balance Sheets.
Income Taxes - We are not a taxable entity for federal income tax purposes.  As such, we do not directly pay federal income tax. Our taxable income or loss, which may vary substantially from the net income or loss reported in our Consolidated Statements of Income, is included in the federal income tax returns of each partner.  The aggregate difference in the basis of our net assets for financial and income tax purposes cannot be readily determined, as we do not have access to all information about each partner’s tax attributes related to us.
Our corporate subsidiaries are required to pay federal and state income taxes.  Deferred income taxes are provided for the difference between the financial statement and income tax basis of assets and liabilities and carryforward items based on income tax laws and rates existing at the time the temporary differences are expected to reverse.  Except for the regulated companies, the effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date of the rate change.  For regulated companies, the effect on deferred tax assets and liabilities of a change in tax rates is recorded as regulatory assets and regulatory liabilities in the period that includes the enactment date, if, as a result of an action by a regulator, it is probable that the effect of the change in tax rates will be recovered from or returned to customers through future rates.
We utilize a more-likely-than-not recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position that is taken or expected to be taken in a tax return.  We reflect penalties and interest as part of income tax expense as they become applicable for tax provisions that do not meet the more-likely-than-not recognition threshold and measurement attribute.  During 2014, 2013 and 2012, our tax positions did not require an establishment of a material reserve.
We file numerous consolidated and separate income tax returns with federal tax authorities of the United States and Canada along with the tax authorities of several states.  There are no United States federal audits or statute waivers at this time. See Note L for additional discussion of income taxes.
Asset Retirement Obligations - Asset retirement obligations represent legal obligations associated with the retirement of long-lived assets that result from the acquisition, construction, development and/or normal use of the asset.  Certain of our natural gas gathering and processing facilities, and our natural gas liquids and pipeline facilities are subject to agreements or regulations that give rise to our asset retirement obligations for removal or other disposition costs associated with retiring the assets in place upon the discontinued use of the assets.  We recognize the fair value of a liability for an asset retirement obligation in the period when it is incurred if a reasonable estimate of the fair value can be made.  We are not able to estimate reasonably the fair value of the asset retirement obligations for portions of our assets, primarily certain pipeline assets, because the settlement dates are indeterminable given our expected continued use of the assets with proper maintenance. We expect our pipeline assets, for which we are unable to estimate reasonably the fair value of the asset retirement obligation, will continue in operation as long as supply and demand for natural gas and natural gas liquids exists. Based on the widespread use of natural gas for heating and cooking activities for residential users and electric-power generation for commercial users, as well as use of natural gas liquids by the petrochemical industry, we expect supply and demand to exist for the foreseeable future.
For our assets that we are able to make an estimate, the fair value of the liability is added to the carrying amount of the associated asset, and this additional carrying amount is depreciated over the life of the asset.  The liability is accreted at the end of each period through charges to operating expense.  If the obligation is settled for an amount other than the carrying amount of the liability, we will recognize a gain or loss on settlement.  The depreciation and accretion expense are immaterial to our consolidated financial statements.
In accordance with long-standing regulatory treatment, we collect, through rates, the estimated costs of removal on certain regulated properties through depreciation expense, with a corresponding credit to accumulated depreciation and amortization. These removal costs collected through rates include legal and nonlegal removal obligations; however, the amounts collected in excess of the asset removal costs incurred are accounted for as a regulatory liability for financial reporting purposes. Historically, the regulatory authorities that have jurisdiction over our regulated operations have not required us to quantify this amount; rather, these costs are addressed prospectively in depreciation rates and are set in each general rate order.  We have made an estimate of our regulatory liability using current rates since the last general rate order in each of our jurisdictions; however, for financial reporting purposes, significant uncertainty exists regarding the ultimate disposition of this regulatory liability pending, among other issues, clarification of regulatory intent.  We continue to monitor regulatory requirements, and the liability may be adjusted as more information is obtained.
Contingencies - Our accounting for contingencies covers a variety of business activities, including contingencies for legal and environmental exposures.  We accrue these contingencies when our assessments indicate that it is probable that a liability has been incurred or an asset will not be recovered and an amount can be estimated reasonably.  We expense legal fees as incurred and base our legal liability estimates on currently available facts and our estimates of the ultimate outcome or resolution. Accruals for estimated losses from environmental remediation obligations generally are recognized no later than completion of a remediation feasibility study.  Recoveries of environmental remediation costs from other parties are recorded as assets when their receipt is deemed probable.  Our expenditures for environmental evaluation, mitigation, remediation and compliance to date have not been significant in relation to our financial position or results of operations, and our expenditures related to environmental matters had no material effect on earnings or cash flows during 2014, 2013 and 2012. Actual results may differ from our estimates resulting in an impact, positive or negative, on earnings.  See Note O for additional discussion of contingencies.
Recently Issued Accounting Standards Update - 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 will adopt this guidance in the first quarter 2016, and we are evaluating the impact on us.
In November 2014, the FASB issued ASU 2014-17, “Business Combination (Topic 805): Pushdown Accounting,” which provides an acquired entity with an option to apply pushdown accounting in its separate financial statements when a change-in-control event occurs. An acquired entity may elect the option to apply pushdown accounting in the reporting period in which the change-in-control event occurs. The standard applies to all entities and was effective on November 18, 2014. We adopted this guidance beginning in the fourth quarter 2014, and we do not expect it to materially impact 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 will 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. This update will be effective for interim and annual periods that begin on or after December 15, 2016, with either retrospective application for all periods presented or retrospective application with a cumulative effect adjustment. We will adopt this guidance beginning in the first quarter 2017, and we are evaluating the impact on us.
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 will adopt this guidance beginning in the first quarter 2015, and it could impact us in the future if we dispose of any individually significant components.

ACQUISITIONS_Notes

ACQUISITIONS (Notes)	12 Months Ended
	Dec. 31, 2014
Acquisition [Abstract]
Mergers, Acquisitions and Dispositions Disclosures [Text Block]
	B.	ACQUISITIONS
	West Texas LPG Acquisition - In November 2014, we completed the acquisition of an 80 percent interest in the West Texas LPG Pipeline Limited Partnership (WTLPG) and a 100 percent interest in the Mesquite Pipeline for approximately $800 million from affiliates of Chevron Corporation, and we became the operator of both pipelines. Financing to close this transaction came from available cash on hand and borrowings under our existing $1.7 billion commercial paper program.
	The acquisition consists of approximately 2,600 miles of natural gas liquids gathering pipelines extending from the Permian Basin in southeastern New Mexico to East Texas and Mont Belvieu, Texas. The acquired pipelines access NGL supply from producers actively developing the Delaware, Midland and Central Basins in the Permian Basin, in addition to the Barnett Shale, East Texas and north Louisiana regions. The pipeline system increased our natural gas liquids gathering system by approximately 60 percent to nearly 7,100 miles of natural gas liquids gathering pipelines and added approximately 285,000 barrels per day of NGL capacity. These assets are expected to provide us additional fee-based earnings and our natural gas liquids infrastructure with access to a new natural gas liquids supply basin.
	We accounted for the West Texas LPG acquisition as a business combination which, among other things, requires assets acquired and liabilities assumed to be measured at their acquisition-date fair values.
	Our consolidated balance sheet as of December 31, 2014, reflects the preliminary purchase price allocation based on available information and is subject to customary working capital adjustments. We are reviewing the valuation to determine the final purchase price allocation. The preliminary purchase price allocation and assessment of the fair value of the assets acquired as of the acquisition date were as follows (in thousands):
	Cash		$	13,839
	Accounts receivable		9,132
	Other current assets		3,369
	Property, plant and equipment
	Regulated		807,601
	Nonregulated		153,919
	Total property, plant and equipment		961,520
	Total fair value of assets acquired		987,860
	Accounts payable		(8,621		)
	Other current liabilities		(1,553		)
	Total fair value of liabilities acquired		(10,174		)
	Less: fair value of noncontrolling interest		(162,913		)
	Net assets acquired		814,773
	Less: cash received		(13,839		)
	Net cash paid for acquisition		$	800,934
	We consolidate West Texas LPG as we control the system. Beginning November 29, 2014, the results of operations for West Texas LPG are included in our Natural Gas Liquids segment. We have recorded noncontrolling interests in consolidated subsidiaries on our Consolidated Statements of Income and Consolidated Balance Sheets to recognize the portion of West Texas LPG that we do not own. The portion of the assets and liabilities of West Texas LPG acquired attributable to noncontrolling interests was accounted for as noncash activity. The fair value of the noncontrolling interest of West Texas LPG was estimated by applying a market approach.
	Revenues and earnings related to West Texas LPG have been included within the Consolidated Statement of Income since the acquisition date. Supplemental pro forma revenue and earnings reflecting this acquisition as if it had occurred as of January 1, 2013, are not materially different from the information presented in the accompanying Consolidated Statements of Income and are, therefore, not presented.
	The limited partnership agreement of WTLPG provides that distributions to the partners are to be made on a pro rata basis according to each partner’s ownership interest.  Cash distributions to the partners for a calendar quarter are currently declared and paid by WTLPG in the next succeeding calendar quarter.  Any changes to, or suspension of, the cash distributions from WTLPG requires the approval of a minimum of 90 percent of the ownership interest and a minimum of two general partners of WTLPG. Cash distributions are equal to 100 percent of distributable cash as defined in the limited partnership agreement of WTLPG.
	Sage Creek - On September 30, 2013, we completed for $305 million the acquisition of certain natural gas gathering and processing, and natural gas liquids facilities in Converse and Campbell counties, Wyoming, in the NGL-rich Niobrara Shale area of the Powder River Basin. The Sage Creek acquisition consists primarily of a 50 MMcf/d natural gas processing facility, the Sage Creek plant, and related natural gas gathering and natural gas liquids infrastructure. Included in the acquisition were supply contracts providing for long-term acreage dedications from producers in the area, which are structured with POP and fee-based contractual terms. The acquisition is complementary to our existing natural gas liquids assets and provides additional natural gas gathering and processing and natural gas liquids gathering capacity in a region where producers are actively drilling for crude oil and NGL-rich natural gas.
	This acquisition was accounted for as a business combination. The excess of cost over those fair values was recorded as goodwill. The purchase price and assessment of the fair value of the assets acquired were as follows:
			Natural Gas			Natural Gas		Total
			Gathering and			Liquids
			Processing
	Property, plant and equipment		(Thousands of dollars)
	Gathering pipelines and related equipment		$	41,129		$	18,045	$	59,174
	Processing and fractionation and related equipment		50,595			—		50,595
	General plant and other		120			—		120
	Intangible assets		40,000			63,000		103,000
	Identifiable assets acquired		131,844			81,045		212,889
	Goodwill		20,000			72,000		92,000
	Total purchase price		$	151,844		$	153,045	$	304,889
	Identifiable intangible assets recognized in the Sage Creek acquisition are primarily related to natural gas gathering and processing and natural gas liquids gathering and fractionation supply contracts with acreage dedications and customer relationships. The basis for determining the value of these intangible assets is the estimated future net cash flows to be derived from acquired supply contracts and customer relationships, which are offset with appropriate charges for the use of contributory assets and discounted using a risk-adjusted discount rate. Those intangible assets are being amortized on a straight-line basis over an initial 20-year period for our Natural Gas Gathering and Processing segment and an initial 30-year period for our Natural Gas Liquids segment which represents a portion of the term over which the customer contracts and relationships are expected to contribute to our cash flows.
	Revenues and earnings related to the Sage Creek acquisition are included within the Consolidated Statements of Income since the acquisition date. Supplemental pro forma revenue and earnings reflecting this acquisition as if it had occurred as of January 1, 2012, are not materially different from the information presented in the accompanying Consolidated Statements of Income and are, therefore, not presented.
	Maysville - In December 2013, we acquired the remaining 30 percent undivided interest in the Maysville, Oklahoma, natural gas processing facility for $90 million. Beginning December 1, 2013, the results of operations for our 100 percent interest are included in our Natural Gas Gathering and Processing segment.

FAIR_VALUE_MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS
	C.	FAIR VALUE MEASUREMENTS
	Recurring Fair Value Measurements - The following tables set forth our recurring fair value measurements for the periods indicated:
			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 posted no cash collateral.
	(b) - Included in other current assets, other assets or other current liabilities in our Consolidated Balance Sheets.
			December 31, 2013
			Level 1			Level 2			Level 3			Total - Gross			Netting (a)			Total - Net (b)
			(Thousands of dollars)
	Derivative assets
	Commodity contracts
	Financial contracts		$	—		$	3,657		$	2,812		$	6,469		$	(1,746	)	$	4,723
	Physical contracts		—			—			2,023			2,023			(946		)	1,077
	Interest-rate contracts		—			54,503			—			54,503			—			54,503
	Total derivative assets		$	—		$	58,160		$	4,835		$	62,995		$	(2,692	)	$	60,303
	Derivative liabilities
	Commodity contracts
	Financial contracts		$	—		$	(2,953	)	$	(2,154	)	$	(5,107	)	$	1,746		$	(3,361	)
	Physical contracts		—			—			(3,463		)	(3,463		)	946			(2,517		)
	Total derivative liabilities		$	—		$	(2,953	)	$	(5,617	)	$	(8,570	)	$	2,692		$	(5,878	)
	(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, 2013, we had no cash collateral held or 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:
			Years Ended December 31,
	Derivative Assets (Liabilities)		2014			2013
			(Thousands of dollars)
	Net assets (liabilities) at beginning of period		$	(782	)	$	(2,423	)
	Total realized/unrealized gains (losses):
	Included in earnings (a)		(927		)	959
	Included in other comprehensive income (loss)		7,260			682
	Purchases, issuances and settlements		3,734			—
	Net assets (liabilities) at end of period		$	9,285		$	(782	)
	Total gains (losses) for the period included in earnings		$	31		$	959
	attributable to the change in unrealized gains (losses)
	relating to assets and liabilities still held as of the end
	of the period (a)
	(a) - Included in commodity sales revenues in our Consolidated Statements of Income.
	During the years ended December 31, 2014 and 2013, 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 long-term debt outstanding, including current maturities, was $6.4 billion and $6.5 billion at December 31, 2014 and 2013, respectively.  The book value of the aggregate of our long-term debt outstanding, including current maturities, was $6.0 billion and $6.1 billion at December 31, 2014 and 2013, respectively.  The estimated fair value of the aggregate of our long-term debt 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.
	During 2014, we recorded a noncash impairment to our equity investment in Bighorn Gas Gathering. The valuation of this investment required use of significant unobservable inputs. We used an income approach to estimate the fair value of our investment. Our discounted cash flow analysis included the following inputs that are not readily available: a discount rate reflective of our cost of capital and estimated contract rates, volumes, operating and maintenance costs and capital expenditures. The estimated fair value of this investment is classified as Level 3. See Note M for additional information about our investment in Bighorn Gas Gathering and the impairment charge.

RISK_MANAGEMENT_AND_HEDGING_AC

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES
	D.	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 sales and financial derivatives to secure a certain price for a portion of our natural gas, condensate and NGL products.  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 are also 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 basis risk primarily as a result of the relative value of NGL purchases at one location and sales at another location. To a lesser extent, we are 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 to reduce the impact of price fluctuations related to NGLs.  At December 31, 2014 and 2013, there were no financial derivative instruments with respect to our natural gas liquids operations.
	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 December 31, 2014 and 2013, 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 and 2013, we had forward-starting interest-rate swaps with notional amounts totaling $900 million and $400 million, respectively, that have been 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. At December 31, 2014, notional amounts totaling $400 million have settlement dates greater than 12 months.
	Fair Values of Derivative Instruments - See Note A 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:
			December 31, 2014								December 31, 2013
			Assets (a)				(Liabilities) (a)				Assets (a)				(Liabilities) (a)
			(Thousands of dollars)
	Derivatives designated as hedging instruments
	Commodity contracts
	Financial contracts		$	43,234			$	(1,137	)		$	6,469			$	(5,107	)
	Physical contracts		9,922				—				1,064				(3,463		)
	Interest-rate contracts		2,288				(44,843		)		54,503				—
	Total derivatives designated as hedging instruments		55,444				(45,980		)		62,036				(8,570		)
	Derivatives not designated as hedging instruments
	Commodity contracts
	Physical contracts		—				(23		)		959				—
	Total derivatives not designated as hedging instruments		—				(23		)		959				—
	Total derivatives		$	55,444			$	(46,003	)		$	62,995			$	(8,570	)
	(a) - Included on a net basis in other current assets, other assets or other current liabilities on 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:
				December 31, 2014								December 31, 2013
		Contract		Purchased/				Sold/				Purchased/				Sold/
		Type		Payor				Receiver				Payor				Receiver
	Derivatives designated as hedging instruments:
	Cash flow hedges
	Fixed price
	-Natural gas (Bcf)	Futures and swaps		—				(41.2		)		—				(48.1		)
	-Crude oil and NGLs (MMBbl)	Futures, forwards and swaps		—				(0.5		)		—				(4.0		)
	Basis
	-Natural gas (Bcf)	Futures and swaps		—				(41.2		)		—				(48.1		)
	Interest-rate contracts (Millions of dollars)	Forward-starting		$	900			$	—			$	400			$	—
		swaps
	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 December 31, 2014, our Consolidated Balance Sheet reflected a net unrealized loss of $91.8 million in accumulated other comprehensive loss. The portion of accumulated other comprehensive loss attributable to our commodity derivative financial instruments is a gain of $53.5 million, which will be realized within the next 12 months as the forecasted transactions affect earnings and if commodity prices remain at the current levels. The amount deferred in accumulated other comprehensive loss attributable to our settled interest-rate swaps is a loss of $99.4 million, which will be recognized over the life of the long-term, fixed-rate debt. We expect that losses of $10.8 million 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, 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 loss for the periods indicated:
	Derivatives in Cash Flow Hedging Relationships		Years Ended December 31,
			2014				2013				2012
			(Thousands of dollars)
	Commodity contracts		$	32,354			$	(14,475	)		$	46,804
	Interest-rate contracts		(96,993		)		46,616				(36,509		)
	Total unrealized gain (loss) recognized in other comprehensive loss on derivatives(effective portion)		$	(64,639	)		$	32,141			$	10,295
	The following table sets forth the effect of cash flow hedges on our Consolidated Statements of Income for the periods indicated:
	Derivatives in Cash Flow		Location of Gain (Loss) Reclassified from
	Hedging Relationships		Accumulated Other Comprehensive Loss into		Years Ended December 31,
			Net Income (Effective Portion)		2014				2013				2012
					(Thousands of dollars)
	Commodity contracts		Commodity sales revenues		$	(21,052	)		$	1,689			$	61,526
	Interest-rate contracts		Interest expense		(10,601		)		(10,033		)		(2,997		)
	Total gain (loss) reclassified from accumulated other comprehensive loss				$	(31,653	)		$	(8,344	)		$	58,529
	into net income on derivatives (effective portion)
	Ineffectiveness related to our cash flow hedges was not material for the years ended December 31, 2014, 2013 and 2012.  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 2014, 2013 and 2012.
	Credit Risk - Prior to March 31, 2014, all of our commodity derivative financial contracts were with our affiliate ONEOK Energy Services Company, a subsidiary of ONEOK. ONEOK Energy Services Company entered into similar commodity derivative financial contracts with third parties at our direction and on our behalf. On March 31, 2014, ONEOK completed the accelerated wind down of ONEOK Energy Services Company. In the first quarter 2014, outstanding commodity derivative positions with third parties entered into by ONEOK Energy Services Company on our behalf were transferred to us. Beginning in the second quarter 2014, we enter into all commodity derivative financial contracts directly with unaffiliated third parties.
	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 as of December 31, 2014.
	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 December 31, 2014, the net credit exposure from our derivative assets is primarily with investment-grade companies in the financial services sector.

PROPERTY_PLANT_AND_EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT
	E.	PROPERTY, PLANT AND EQUIPMENT
	The following table sets forth our property, plant and equipment by property type, for the periods indicated:
			Estimated Useful	December 31,			December 31,
			Lives (Years)	2014			2013
				(Thousands of dollars)
	Nonregulated
	Gathering pipelines and related equipment		5 to 40	$	2,449,343		$	2,173,271
	Processing and fractionation and related equipment		3 to 40	2,880,572			2,295,983
	Storage and related equipment		5 to 54	478,276			362,704
	Transmission pipelines and related equipment		5 to 54	518,585			302,718
	General plant and other		2 to 60	142,276			116,468
	Construction work in process		—	1,233,808			1,068,428
	Regulated
	Storage and related equipment		5 to 54	115,799			135,922
	Natural gas transmission pipelines and related equipment		5 to 77	1,478,035			1,420,517
	Natural gas liquids transmission pipelines and related equipment		5 to 80	3,822,799			2,049,461
	General plant and other		2 to 53	63,424			53,315
	Construction work in process		—	194,700			776,261
	Property, plant and equipment			13,377,617			10,755,048
	Accumulated depreciation and amortization - nonregulated			(1,123,261		)	(1,004,614		)
	Accumulated depreciation and amortization - regulated			(718,823		)	(648,034		)
	Net property, plant and equipment			$	11,535,533		$	9,102,400
	The average depreciation rates for our regulated property are set forth, by segment, in the following table for the periods indicated:
			Years Ended December 31,
			2014	2013		2012
	Natural Gas Liquids		2.00%	2.00%		1.90%
	Natural Gas Pipelines		2.10%	2.20%		2.20%
	We incurred liabilities for construction work in process that had not been paid at December 31, 2014, 2013 and 2012, of $187.2 million, $226.7 million and $216.5 million, respectively. Such amounts are not included in capital expenditures (less allowance for equity funds used during construction) on the Consolidated Statements of Cash Flows.

GOODWILL_AND_INTANGIBLE_ASSETS

GOODWILL AND INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS
	F.	GOODWILL AND INTANGIBLE ASSETS
	Goodwill - The following table sets forth our goodwill, by segment, for the periods indicated:
		December 31,				December 31,
		2014				2013
		(Thousands of dollars)
	Natural Gas Gathering and Processing	$	112,141			$	112,141
	Natural Gas Liquids	247,566				247,566
	Natural Gas Pipelines	129,011				129,011
	Total goodwill	$	488,718			$	488,718
	In September 2013 we completed the Sage Creek acquisition which included goodwill of $20 million and $72 million for our Natural Gas Gathering and Processing segment and Natural Gas Liquids segment, respectively. For additional information related to the acquisition, see Note B.
	Intangible Assets - Our intangible assets relate primarily to contracts acquired through acquisitions in our Natural Gas Gathering and Processing and Natural Gas Liquids segments, which are being amortized over periods of 20 to 40 years. Amortization expense for intangible assets for 2014, 2013 and 2012 was $11.8 million, $8.7 million and $7.7 million, respectively, and the aggregate amortization expense for each of the next five years is estimated to be approximately $11.8 million. The following table reflects the gross carrying amount and accumulated amortization of intangible assets for the periods presented:
			December 31,				December 31,
			2014				2013
			(Thousands of dollars)
	Gross intangible assets		$	411,650			$	409,650
	Accumulated amortization		(78,010		)		(66,188		)
	Net intangible assets		$	333,640			$	343,462

CREDIT_FACILITIES_AND_SHORTTER

CREDIT FACILITIES AND SHORT-TERM NOTES PAYABLE	12 Months Ended
	Dec. 31, 2014
Short-term Debt [Abstract]
CREDIT FACILITIES AND SHORT-TERM NOTES PAYABLE
	G.	CREDIT FACILITIES AND SHORT-TERM NOTES PAYABLE
	Partnership Credit Agreement - The amount of short-term borrowings authorized by our general partner’s Board of Directors is $2.5 billion.  At December 31, 2014, we had $1.1 billion of commercial paper outstanding, $14.0 million letters of credit issued and no borrowings outstanding under our Partnership Credit Agreement.
	Our Partnership Credit Agreement, which was amended and restated effective on January 31, 2014, and expires in January 2019, is a $1.7 billion revolving credit facility and includes a $100 million sublimit for the issuance of standby letters of credit, a $150 million swingline sublimit and an option to request an increase in the size of the facility to an aggregate of $2.4 billion from $1.7 billion by either commitments from new lenders or increased commitments from existing lenders. Our Partnership Credit Agreement is available for general partnership purposes. During the second quarter 2014, we increased the size of our commercial paper program to $1.7 billion from $1.2 billion. In addition, in February 2015, we notified our lenders of our intent to exercise our option to increase the capacity of the facility to an aggregate of $2.4 billion by increased commitments from existing lenders and/or commitments from one or more new lenders, which is pending lenders’ approval. 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 rating, 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, and ONEOK does not guarantee our debt, commercial paper or other similar commitments.
	Our Partnership Credit Agreement contains financial, operational and legal covenants that remained substantially the same with the amendment. 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 of the acquisition 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 our Partnership Credit Agreement, if any, may become due and payable immediately. At December 31, 2014, our ratio of indebtedness to adjusted EBITDA was 3.7 to 1, and we were in compliance with all covenants under our Partnership Credit Agreement.

LONGTERM_DEBT

LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2014
Long-term Debt, Unclassified [Abstract]
LONG-TERM DEBT
	H.	LONG-TERM DEBT
	All notes are senior unsecured obligations, ranking equally in right of payment with all of our existing and future unsecured senior indebtedness.  The following table sets forth our long-term debt for the periods indicated:
			December 31,			December 31,
			2014			2013
			(Thousands of dollars)
	ONEOK Partners
	$650,000 at 3.25% due 2016		$	650,000		$	650,000
	$450,000 at 6.15% due 2016		450,000			450,000
	$400,000 at 2.0% due 2017		400,000			400,000
	$425,000 at 3.2% due 2018		425,000			425,000
	$500,000 at 8.625% due 2019		500,000			500,000
	$900,000 at 3.375 % due 2022		900,000			900,000
	$425,000 at 5.0 % due 2023		425,000			425,000
	$600,000 at 6.65% due 2036		600,000			600,000
	$600,000 at 6.85% due 2037		600,000			600,000
	$650,000 at 6.125% due 2041		650,000			650,000
	$400,000 at 6.2% due 2043		400,000			400,000
	Guardian Pipeline
	Average 7.88% due 2022		59,557			67,208
	Total long-term notes payable		6,059,557			6,067,208
	Unamortized debt discount and other		(13,528		)	(14,691		)
	Current maturities		(7,650		)	(7,650		)
	Long-term debt		$	6,038,379		$	6,044,867
	The aggregate maturities of long-term debt outstanding for years 2015 through 2019 are shown below:
			ONEOK			Guardian			Total
			Partners			Pipeline
			(Millions of dollars)
	2015		$	—		$	7.7		$	7.7
	2016		$	1,100.00		$	7.7		$	1,107.70
	2017		$	400		$	7.7		$	407.7
	2018		$	425		$	7.7		$	432.7
	2019		$	500		$	7.7		$	507.7
	Debt issuance and maturity - In September 2013, we completed an underwritten public offering of $1.25 billion of senior notes, consisting of $425 million, 3.2 percent senior notes due 2018, $425 million, 5.0 percent senior notes due 2023 and $400 million, 6.2 percent senior notes due 2043. A portion of the net proceeds from the offering of approximately $1.24 billion was used to repay amounts outstanding under our commercial paper program, and the balance was used for general partnership purposes, including but not limited to capital expenditures.
	In September 2012, we completed an underwritten public offering of $1.3 billion of senior notes, consisting of $400 million, 2.0 percent senior notes due 2017 and $900 million, 3.375 percent senior notes due 2022. A portion of the net proceeds from the offering of approximately $1.29 billion was used to repay amounts outstanding under our commercial paper program, and the balance was used for general partnership purposes, including but not limited to capital expenditures.
	We used a portion of the proceeds from our March 2012 equity issuance to repay our $350 million, 5.9 percent senior notes due April 2012.
	Debt covenants - Our senior 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.
	We may redeem our senior notes due 2016 (6.15 percent), 2019, 2036 and 2037, in whole or in part, at any time prior to their maturity 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.
	We may redeem our senior notes due 2017 and our senior notes due 2022 at par starting one month and three months, respectively, before their maturity dates. We may redeem our senior notes due 2016 (3.25 percent) and 2041 at a redemption price equal to the principal amount, plus accrued and unpaid interest, starting one month and six 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. We may redeem our senior notes due 2018, 2023 and 2043 at par, plus accrued and unpaid interest to the redemption date, starting one month, three months, and six 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 are structurally subordinate to any of the existing and future debt and other liabilities of any nonguarantor subsidiaries.
	ONEOK Partners Debt Guarantee - Our senior notes are guaranteed fully and unconditionally on a senior unsecured basis by the Intermediate Partnership.  The guarantee ranks equally in right of payment to all of the Intermediate Partnership’s existing and future unsecured senior indebtedness.  See Note R for additional information on the guarantee.  Our long-term debt is nonrecourse to our general partner.
	Guardian Pipeline Senior Notes - These senior notes were issued under a master shelf agreement dated November 8, 2001, with certain financial institutions.  Principal payments are due quarterly through 2022.  Guardian Pipeline’s senior notes contain financial covenants that require the maintenance of certain financial ratios as defined in the master shelf agreement based on Guardian Pipeline’s financial position and results of operations.  Upon any breach of these covenants, all amounts outstanding under the master shelf agreement may become due and payable immediately.  At December 31, 2014, Guardian Pipeline was in compliance with its financial covenants.
	Other - We amortize premiums, discounts and expenses incurred in connection with the issuance of long-term debt consistent with the terms of the respective debt instrument.

EQUITY

EQUITY	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
EQUITY
	I.	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 37.8 percent ownership interest in us at December 31, 2014.
	Equity Issuances - 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 to repay commercial paper, fund our capital expenditures and for general partnership purposes.
	We have an “at-the-market” equity program for the offer and sale from time to time of our common units. In November 2014, we entered into an equity distribution agreement in the 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. During 2014, we utilized the remainder of our previous equity distribution agreement in the aggregate amount of $300 million. At December 31, 2014, we had approximately $514 million of registered common units available for issuance under our “at-the-market” equity program.
	During the year ended December 31, 2014, we sold approximately 7.9 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 $402.1 million, which were used for general partnership purposes.
	As a result of these transactions, ONEOK’s aggregate ownership interest in us decreased to 37.8 percent at December 31, 2014, from 41.2 percent at December 31, 2013.
	In August 2013, we completed an underwritten public offering of 11.5 million common units at a public offering price of $49.61 per common unit, generating net proceeds of approximately $553.4 million. In conjunction with this issuance, ONEOK Partners GP contributed approximately $11.6 million in order to maintain its 2 percent general partner interest in us. We used a portion of the proceeds from our August 2013 equity issuance to repay amounts outstanding under our commercial paper program and the balance was used for general partnership purposes.
	During the year ended December 31, 2013, we sold approximately 681 thousand 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 $36.1 million, which were used for general partnership purposes.
	In March 2012, we completed an underwritten public offering of 8.0 million common units at a public offering price of $59.27 per common unit, generating net proceeds of approximately $460 million. We also sold 8.0 million common units to ONEOK in a private placement, generating net proceeds of approximately $460 million. In conjunction with the issuances, ONEOK Partners GP contributed approximately $19 million in order to maintain its 2 percent general partner interest in us.
	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 - The following table sets forth the quarterly cash distribution declared and paid on each of our common and Class B units during the periods indicated:
	Declared for		Distribution		Date Declared		Date Paid
	Quarter Ending		Per Unit
	December 31, 2014		$	0.79	January 15, 2015		February 13, 2015
	September 30, 2014		$	0.775	October 23, 2014		November 14, 2014
	June 30, 2014		$	0.76	July 25, 2014		August 14, 2014
	March 31, 2014		$	0.745	April 18, 2014		May 15, 2014
	December 31, 2013		$	0.73	January 16, 2014		February 14, 2014
	September 30, 2013		$	0.725	October 23, 2013		November 14, 2013
	June 30, 2013		$	0.72	July 25, 2013		August 15, 2013
	March 31, 2013		$	0.715	April 18, 2013		May 15, 2013
	December 31, 2012		$	0.71	January 17, 2013		February 14, 2013
	30-Sep-12		$	0.685	24-Oct-12		14-Nov-12
	30-Jun-12		$	0.66	26-Jul-12		15-Aug-12
	31-Mar-12		$	0.635	19-Apr-12		15-May-12
	31-Dec-11		$	0.61	19-Jan-12		14-Feb-12
	The following table shows our distributions paid during the periods indicated:
			Years Ended December 31,
			2014		2013			2012
			(Thousands, except per unit amounts)
	Distribution per unit		$	3.01	$	2.87		$	2.59
	General partner distributions		$	21,044	$	18,193		$	15,217
	Incentive distributions		304,999		251,664			186,130
	Distributions to general partner		326,043		269,857			201,347
	Limited partner distributions to ONEOK		279,292		266,302			235,442
	Limited partner distributions to other unitholders		446,910		373,554			324,123
	Total distributions paid		$	1,052,245	$	909,713		$	760,912
	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:
			Years Ended December 31,
			2014		2013			2012
			(Thousands, except per unit amounts)
	Distribution per unit		$	3.07	$	2.89		$	2.69
	General partner distributions		$	22,109	$	18,625		$	16,355
	Incentive distributions		326,022		259,466			210,095
	Distributions to general partner		348,131		278,091			226,450
	Limited partner distributions to ONEOK		284,860		268,157			249,600
	Limited partner distributions to other unitholders		472,466		384,988			341,704
	Total distributions declared		$	1,105,457	$	931,236		$	817,754
	Our Class B limited partner units are entitled to receive increased quarterly distributions equal to 110 percent of the distributions paid with respect to our common units.  ONEOK, as the sole holder of our Class B limited partner units, has waived its right to receive the increased quarterly distributions on the Class B units.  ONEOK retains the option to withdraw its waiver of increased distributions on Class B units at any time by giving us no less than 90 days advance notice.  Any such withdrawal of the waiver will be effective with respect to any distribution on the Class B units declared or paid on or after the 90 days following delivery of the notice. The Class B units are eligible to convert into common units on a one-for-one basis at ONEOK’s option.
	If our common unitholders vote at any time to remove ONEOK or its affiliates as our general partner, quarterly distributions payable on the Class B limited partner units would increase to 123.5 percent of the distributions payable with respect to the common units, and distributions payable upon liquidation of the Class B limited partner units would increase to 123.5 percent of the distributions payable with respect to the common units.
	Our income is allocated to the general partner and the limited partners in accordance with their respective partnership percentages, after giving effect to any priority income allocations for incentive distributions that are allocated to the general partner.

ACCUMULATED_OTHER_COMPREHENSIV

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Notes)	12 Months Ended
	Dec. 31, 2014
Comprehensive Income (Loss) Note [Text Block]
	J.	ACCUMULATED OTHER COMPREHENSIVE LOSS
	The following table sets forth the balance in accumulated other comprehensive income (loss) for the periods indicated:
			Accumulated
			Other
			Comprehensive
			Loss (a)
			(Thousands of dollars)
	1-Jan-13		$	(99,322	)
	Other comprehensive income (loss) before reclassifications		32,141
	Amounts reclassified from accumulated other comprehensive income (loss)		8,344
	Net current-period other comprehensive income (loss) attributable to ONEOK Partners		40,485
	31-Dec-13		(58,837		)
	Other comprehensive income (loss) before reclassifications		(64,639		)
	Amounts reclassified from accumulated other comprehensive income (loss)		31,653
	Net current-period other comprehensive income (loss) attributable to ONEOK Partners		(32,986		)
	31-Dec-14		$	(91,823	)
	(a) All amounts are attributable to unrealized gains (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		Year Ended December 31,						Affected Line Item in the
	Comprehensive Income (Loss) Components		2014			2013			Consolidated Statements of Income
			(Thousands of dollars)
	Unrealized (gains) losses on risk-management assets/liabilities
	Commodity contracts		$	21,052		$	(1,689	)	Commodity sales revenues
	Interest-rate contracts		10,601			10,033			Interest expense
	Total reclassifications for the period attributable to ONEOK Partners		$	31,653		$	8,344		Net income attributable to ONEOK Partners

LIMITED_PARTNERS_NET_INCOME_PE

LIMITED PARTNERS' NET INCOME PER UNIT LIMITED PARTNERS' NET INCOME PER UNIT (Notes)	12 Months Ended
	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Limited Partners' Net Income Per Unit and Distributions to Partners [Text Block]
	K.	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 unit 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 amount of incentive distributions allocated to our general partner totaled $326.0 million, $259.5 million and $210.1 million for 2014, 2013 and 2012, respectively.
	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.

INCOME_TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
INCOME TAXES
	L.	INCOME TAXES
	The following table sets forth our provision for income taxes for the periods indicated:
			Years Ended December 31,
			2014			2013			2012
			(Thousands of dollars)
	Current income tax provision
	Federal		$	59		$	56		$	(156	)
	State		1,777			5,358			3,446
	Total current income tax provision		1,836			5,414			3,290
	Deferred income tax provision
	Federal		5,033			4,303			6,330
	State		5,799			1,141			485
	Total deferred income tax provision		10,832			5,444			6,815
	Total provision for income taxes		$	12,668		$	10,858		$	10,105
	The following table is a reconciliation of our income tax provision for the periods indicated:
			Years Ended December 31,
			2014			2013			2012
			(Thousands of dollars)
	Income before income taxes		$	924,003		$	814,841		$	898,533
	Less: Net income attributable to noncontrolling interests		1,037			357			438
	Income attributable to ONEOK Partners, L.P. before income taxes		922,966			814,484			898,095
	Federal statutory income tax rate		35		%	35		%	35		%
	Provision for federal income taxes		323,038			285,069			314,333
	Partnership earnings not subject to tax		(318,021		)	(280,992		)	(307,839		)
	State income taxes, net of federal benefit		7,576			6,095			4,530
	Other, net		75			686			(919		)
	Income tax provision		$	12,668		$	10,858		$	10,105
	The following table sets forth the tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and liabilities for the periods indicated. The prior period has been recast to conform to the current year presentation.
			Years Ended December 31,
			2014			2013
			(Thousands of dollars)
	Deferred tax assets
	Federal and state net operating loss		$	3,179		$	1,410
	Other		1,626			1,521
	Total deferred tax assets		4,805			2,931
	Deferred tax liabilities
	Excess of tax over book depreciation		61,120			48,433
	Regulatory assets		1,962			1,978
	Total deferred tax liabilities		63,082			50,411
	Net deferred tax liabilities		$	58,277		$	47,480
	Income taxes payable at December 31, 2014 and 2013, were not material.

UNCONSOLIDATED_AFFILIATES

UNCONSOLIDATED AFFILIATES	12 Months Ended
	Dec. 31, 2014
Equity Method Investments and Joint Ventures [Abstract]
UNCONSOLIDATED AFFILIATES
	M.	UNCONSOLIDATED AFFILIATES
	Investments in Unconsolidated Affiliates - The following table sets forth our investments in unconsolidated affiliates for the periods indicated:
			Net		December 31,				December 31,
			Ownership		2014				2013
			Interest
					(Thousands of dollars)
	Northern Border Pipeline		50%		$	387,253			$	404,803
	Overland Pass Pipeline Company		50%		466,977				466,671
	Fort Union Gas Gathering		37%		127,876				125,220
	Bighorn Gas Gathering		49%		7,924				87,837
	Other		Various		142,623				145,307
	Investments in unconsolidated affiliates (a)				$	1,132,653			$	1,229,838
	(a) - Equity method goodwill (Note A) was $170.9 million and $224.3 million at December 31, 2014 and 2013, respectively.
	Equity Earnings from Investments - The following table sets forth our equity earnings from investments for the periods indicated:
			Years Ended December 31,
			2014				2013				2012
			(Thousands of dollars)
	Share of investee earnings (loss)
	Northern Border Pipeline		$	69,819			$	65,046			$	72,705
	Overland Pass Pipeline Company		25,906				20,461				20,043
	Fort Union Gas Gathering		16,619				15,826				17,218
	Bighorn Gas Gathering (a)		(25,621		)		1,952				3,820
	Other		7,701				7,232				9,238
	Total share of investee earnings		$	94,424			$	110,517			$	123,024
	Impairment of investment in Bighorn Gas Gathering		(53,421		)		—				—
	Equity earnings from investments		$	41,003			$	110,517			$	123,024
	(a) Includes proportionate share of investee impairment of long-lived assets charge of $23.0 million in 2014.
	Unconsolidated Affiliates Financial Information - The following tables set forth summarized combined financial information of our unconsolidated affiliates for the periods indicated:
			December 31,				December 31,
			2014				2013
			(Thousands of dollars)
	Balance Sheet
	Current assets		$	153,293			$	155,310
	Property, plant and equipment, net		$	2,440,714			$	2,557,571
	Other noncurrent assets		$	35,668			$	34,478
	Current liabilities		$	95,026			$	98,967
	Long-term debt		$	428,385			$	442,103
	Other noncurrent liabilities		$	73,767			$	58,221
	Accumulated other comprehensive loss		$	(2,063	)		$	(2,291	)
	Owners’ equity		$	2,034,560			$	2,150,359
			Years Ended December 31,
			2014				2013				2012
			(Thousands of dollars)
	Income Statement
	Operating revenues		$	548,491			$	528,665			$	573,197
	Operating expenses (a)		$	309,990			$	256,292			$	269,858
	Net income (a)		$	214,410			$	248,998			$	279,766
	Distributions paid to us		$	139,019			$	137,498			$	155,741
	(a) Includes long-lived asset impairment charge on Bighorn Gas Gathering in 2014.
	We incurred expenses in transactions with unconsolidated affiliates of $62.0 million, $53.8 million and $36.1 million for 2014, 2013 and 2012, respectively, primarily related to Overland Pass Pipeline Company and Northern Border Pipeline. Accounts payable to our equity method investees at December 31, 2014 and 2013, were $20.5 million and $6.9 million, respectively.
	Overland Pass Pipeline Company - The Overland Pass Pipeline Company limited liability company agreement provides that distributions to Overland Pass Pipeline Company’s members are to be made on a pro rata basis according to each member’s percentage interest.  The Overland Pass Pipeline Company Management Committee determines the amount and timing of such distributions.  Any changes to, or suspension of, the cash distributions from Overland Pass Pipeline Company requires the unanimous approval of the Overland Pass Pipeline Management Committee.  Cash distributions are equal to 100 percent of available cash as defined in the limited liability company agreement.
	Northern Border Pipeline - The Northern Border Pipeline partnership agreement provides that distributions to Northern Border Pipeline’s partners are to be made on a pro rata basis according to each partner’s percentage interest.  The Northern Border Pipeline Management Committee determines the amount and timing of such distributions.  Any changes to, or suspension of, the cash distribution policy of Northern Border Pipeline requires the unanimous approval of the Northern Border Pipeline Management Committee.  Cash distributions are equal to 100 percent of distributable cash flow as determined from Northern Border Pipeline’s financial statements based upon EBITDA less interest expense and maintenance capital expenditures. Loans or other advances from Northern Border Pipeline to its partners or affiliates are prohibited under its credit agreement.
	During 2013, we made equity contributions to Northern Border Pipeline of approximately $30.8 million.
	In September 2012, Northern Border Pipeline filed with the FERC a settlement with its customers to modify its transportation rates. In January 2013, the settlement was approved and the new rates became effective January 1, 2013. The new long-term transportation rates are approximately 11 percent lower compared with previous rates.
	Bighorn Gas Gathering - 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.
	During 2014, the volumes gathered on the Bighorn Gas Gathering system, in which we own a 49 percent equity interest and which operates in the coal-bed methane area of the Powder River Basin, declined at a rate greater than in prior periods and greater than expected. Due to these additional declines in volumes, Bighorn Gas Gathering recorded an impairment of its underlying assets in September 2014, when the operator determined that the volume decline would be sustained for the foreseeable future. As a result of these developments, we reviewed our equity method investment in Bighorn Gas Gathering for impairment as of September 30, 2014. We recorded noncash impairment charges of $76.4 million related to Bighorn Gas Gathering. The noncash impairment charges are included in equity earnings from investments in our accompanying Consolidated Statements of Income. The net book value of our equity method investment in Bighorn Gas Gathering is $7.9 million at December 31, 2014, and no equity method goodwill remains. We determined that there were no impairments to investments in unconsolidated affiliates in 2013 or 2012.
	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 additional noncash charges to earnings. The net book value of our remaining equity method investments in this dry natural gas area is $206.0 million, which includes $130.5 million of equity method goodwill. We expect the commodity price environment to remain depressed for at least the near term, which has caused producers to announce plans for reduced 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 equity method investments.

RELATEDPARTY_TRANSACTIONS

RELATED-PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
RELATED-PARTY TRANSACTIONS
	N.	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, and for the years ended December 31, 2013 and 2012, 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 and the years ended December 31, 2013 and 2012, 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 and the years ended December 31, 2013 and 2012, 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:
			Years Ended December 31,
			2014		2013		2012
			(Thousands of dollars)
	Revenues		$	53,526	$	340,743	$	352,099
	Expenses
	Cost of sales and fuel		$	10,835	$	37,963	$	33,094
	Administrative and general expenses		330,541		265,448		246,050
	Total expenses		$	341,376	$	303,411	$	279,144
	ONEOK Partners GP made additional general partner contributions to us of approximately $23 million and $12 million in 2014 and 2013, respectively, to maintain its 2 percent general partner interest in connection with the issuances of common units.  See Note I for additional information about cash distributions paid to ONEOK for its general partner and limited partner interests.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES
	O.	COMMITMENTS AND CONTINGENCIES
	Commitments - Operating leases represent future minimum lease payments under noncancelable leases covering office space, pipeline equipment and vehicles.  Rental expense in 2014, 2013 and 2012 was not material. We have no material operating leases. Firm transportation and storage contracts are fixed-price contracts that provide us with firm transportation and storage capacity.  The following table sets forth our firm transportation and storage contract payments for the periods presented:
			Firm
			Transportation
			and Storage
			Contracts
			(Millions of dollars)
	2015		$	33.6
	2016		32.1
	2017		30.4
	2018		29.4
	2019		28.8
	Thereafter		68.5
	Total		$	222.8
	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, wetland 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 years ended December 31, 2014, 2013 and 2012.
	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, 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. However, the 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. We are in the process of evaluating the effects the decision and related pending judicial proceedings at the lower court level may have on our existing operations and the opportunities it creates for 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.
	The rule was most recently amended in December 2014. The EPA has indicated that further amendments may be issued in 2015. Based on the amendments, our understanding of pending stakeholder responses to the NSPS rule and the proposed rule-making, we do not anticipate a material impact to our anticipated capital, operations and maintenance costs resulting from compliance with the regulation. 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 litigation and claims cannot be predicted with certainty, we believe the reasonably possible losses of 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	12 Months Ended
	Dec. 31, 2014
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
SEGMENTS
	P.	SEGMENTS
	Segment Descriptions - Our operations are divided into three reportable business segments, as follows:
	•	our Natural Gas Gathering and Processing segment gathers 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.  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 called 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. Natural Gas Pipelines segment customers include natural gas distribution, electric-generation, natural gas marketing, industrial and major and independent crude oil and natural gas production companies.
	For the years ended December 31, 2014, 2013 and 2012, we had no single customer from which we received 10 percent or more of our consolidated revenues.
	See Note N for additional information about our sales to affiliated customers.
	Operating Segment Information - The following tables set forth certain selected financial information for our operating segments for the periods indicated:
	Year Ended December 31, 2014		Natural Gas			Natural Gas			Natural Gas		Other and			Total
			Gathering and			Liquids (a)			Pipelines (b)		Eliminations
			Processing
			(Thousands of dollars)
	Sales to unaffiliated customers		$	1,478,729		$	10,329,609		$	329,801	$	—		$	12,138,139
	Sales to affiliated customers		41,214			—			12,312		—			53,526
	Intersegment revenues		1,447,665			215,772			8,343		(1,671,780		)	—
	Total revenues		$	2,967,608		$	10,545,381		$	350,456	$	(1,671,780	)	$	12,191,665
	Net margin		$	661,885		$	1,110,085		$	328,521	$	2,626		$	2,103,117
	Operating costs		257,658			296,402			111,037		4,560			669,657
	Depreciation and amortization		123,847			124,071			43,318		—			291,236
	Gain (loss) on sale of assets		219			(572		)	6,786		166			6,599
	Operating income		$	280,599		$	689,040		$	180,952	$	(1,768	)	$	1,148,823
	Equity earnings (loss) from investments		$	(56,141	)	$	27,326		$	69,818	$	—		$	41,003
	Investments in unconsolidated affiliates		$	254,818		$	490,582		$	387,253	$	—		$	1,132,653
	Total assets		$	4,727,201		$	8,082,692		$	1,823,917	$	737		$	14,634,547
	Noncontrolling interests in consolidated subsidiaries		$	4,251		$	163,671		$	—	$	15		$	167,937
	Capital expenditures		$	898,896		$	798,048		$	42,991	$	6,055		$	1,745,990
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $695.9 million, of which $598.1 million related to sales within the segment, net margin of $386.5 million and operating income of $196.1 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $290.0 million, net margin of $242.3 million and operating income of $106.5 million.
	Year Ended December 31, 2013		Natural Gas			Natural Gas			Natural Gas		Other and			Total
			Gathering and			Liquids (a)			Pipelines (b)		Eliminations
			Processing
			(Thousands of dollars)
	Sales to unaffiliated customers		$	665,169		$	10,644,117		$	219,244	$	—		$	11,528,530
	Sales to affiliated customers		238,600			—			102,143		—			340,743
	Intersegment revenues		1,147,713			133,910			4,127		(1,285,750		)	—
	Total revenues		$	2,051,482		$	10,778,027		$	325,514	$	(1,285,750	)	$	11,869,273
	Net margin		$	500,627		$	869,938		$	285,719	$	(9,224	)	$	1,647,060
	Operating costs		193,293			236,638			101,182		(9,600		)	521,513
	Depreciation and amortization		103,962			89,240			43,541		—			236,743
	Gain (loss) on sale of assets		436			843			10,602		—			11,881
	Operating income		$	203,808		$	544,903		$	151,598	$	376		$	900,685
	Equity earnings from investments		$	23,493		$	21,978		$	65,046	$	—		$	110,517
	Investments in unconsolidated affiliates		$	333,179		$	491,856		$	404,803	$	—		$	1,229,838
	Total assets		$	3,949,813		$	6,938,633		$	1,817,675	$	156,487		$	12,862,608
	Noncontrolling interests in consolidated subsidiaries		$	4,521		$	—		$	—	$	15		$	4,536
	Capital expenditures		$	774,379		$	1,128,345		$	34,699	$	1,903		$	1,939,326
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $534.8 million, of which $449.9 million related to sales within the segment, net margin of $327.4 million and operating income of $190.5 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $246.9 million, net margin of $217.6 million and operating income of $90.5 million.
	Year Ended December 31, 2012		Natural Gas			Natural Gas			Natural Gas		Other and			Total
			Gathering and			Liquids (a)			Pipelines (b)		Eliminations
			Processing
			(Thousands of dollars)
	Sales to unaffiliated customers		$	436,629		$	9,176,389		$	217,034	$	—		$	9,830,052
	Sales to affiliated customers		253,136			—			98,963		—			352,099
	Intersegment revenues		825,948			80,274			4,388		(910,610		)	—
	Total revenues		$	1,515,713		$	9,256,663		$	320,385	$	(910,610	)	$	10,182,151
	Net margin		$	455,170		$	907,340		$	286,060	$	(6,738	)	$	1,641,832
	Operating costs		164,033			223,844			101,899		(7,236		)	482,540
	Depreciation and amortization		83,031			74,344			45,726		—			203,101
	Loss on sale of assets		2,278			(932		)	5,390		—			6,736
Operating income		$	210,384		$	608,220		$	143,825	$	498		$	962,927
Equity earnings from investments		$	29,103		$	20,701		$	73,220	$	—		$	123,024
Investments in unconsolidated affiliates		$	333,210		$	494,878		$	393,317	$	—		$	1,221,405
Total assets		$	3,040,198		$	5,620,420		$	1,812,711	$	485,901		$	10,959,230
Noncontrolling interests in consolidated subsidiaries		$	4,752		$	—		$	—	$	15		$	4,767
Capital expenditures		$	566,126		$	968,549		$	25,383	$	455		$	1,560,513
(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $470.6 million, of which $397.7 million related to sales within the segment, net margin of $276.3 million and operating income of $162.8 million.
(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $251.5 million, net margin of $220.3 million and operating income of $99.3 million.

QUARTERLY_FINANCIAL_DATA_UNAUD

QUARTERLY FINANCIAL DATA (UNAUDITED)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Data [Abstract]
QUARTERLY FINANCIAL DATA (UNAUDITED)
	Q.	QUARTERLY FINANCIAL DATA (UNAUDITED)
			First		Second		Third		Fourth
	Year Ended December 31, 2014		Quarter		Quarter		Quarter		Quarter
			(Thousands of dollars, except per unit amounts)
	Revenues		$	3,162,303	$	3,065,735	$	3,119,369	$	2,844,258
	Net margin		$	509,634	$	494,333	$	536,165	$	562,985
	Net income		$	265,468	$	214,511	$	167,320	$	264,036
	Net income attributable to ONEOK Partners, L.P.		$	265,392	$	214,434	$	167,247	$	263,225
	Limited partners’ per unit net income		$	0.81	$	0.54	$	0.32	$	0.67
			First		Second		Third		Fourth
	Year Ended December 31, 2013		Quarter		Quarter		Quarter		Quarter
			(Thousands of dollars, except per unit amounts)
	Revenues		$	2,517,447	$	2,768,179	$	3,134,733	$	3,448,914
	Net margin		$	370,599	$	411,953	$	423,574	$	440,934
	Net income		$	156,685	$	202,454	$	216,400	$	228,444
	Net income attributable to ONEOK Partners, L.P.		$	156,599	$	202,367	$	216,310	$	228,350
	Limited partners’ per unit net income		$	0.42	$	0.62	$	0.64	$	0.67

SUPPLEMENTAL_CONDENSED_CONSOLI

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Supplemental Condensed Consolidating Financial Information
	R.	SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION
	We have no significant assets or operations other than our investment in our wholly 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.  Our Intermediate Partnership guarantees our senior notes and borrowings, if any, under the Partnership Credit Agreement.  The Intermediate Partnership’s guarantee 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 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
			Year Ended December 31, 2014
			Parent			Guarantor				Combined			Consolidating			Total
						Subsidiary				Non-Guarantor			Entries
										Subsidiaries
			(Millions of dollars)
	Revenues
	Commodity sales		$	—		$	—			$	10,725.00		$	—		$	10,725.00
	Services		—			—				1,466.70			—			1,466.70
	Total revenues		—			—				12,191.70			—			12,191.70
	Cost of sales and fuel		—			—				10,088.60			—			10,088.60
	Net margin		—			—				2,103.10			—			2,103.10
	Operating expenses
	Operations and maintenance		—			—				599.1			—			599.1
	Depreciation and amortization		—			—				291.2			—			291.2
	General taxes		—			—				70.6			—			70.6
	Total operating expenses		—			—				960.9			—			960.9
	Gain (loss) on sale of assets		—			—				6.6			—			6.6
	Operating income		—			—				1,148.80			—			1,148.80
	Equity earnings (loss) from investments		910.3			910.3				(28.8		)	(1,750.8		)	41
	Allowance for equity funds used during construction		—			—				14.9			—			14.9
	Other income (expense), net		331.7			331.7				1.2			(663.4		)	1.2
	Interest expense		(331.7		)	(331.7		)		(281.9		)	663.4			(281.9		)
	Income before income taxes		910.3			910.3				854.2			(1,750.8		)	924
	Income taxes		—			—				(12.7		)	—			(12.7		)
	Net income		910.3			910.3				841.5			(1,750.8		)	911.3
	Less: Net income attributable to noncontrolling interests		—			—				1			—			1
	Net income attributable to ONEOK Partners, L.P.		$	910.3		$	910.3			$	840.5		$	(1,750.8	)	$	910.3
			Year Ended December 31, 2013
			Parent			Guarantor				Combined			Consolidating			Total
						Subsidiary				Non-Guarantor			Entries
										Subsidiaries
			(Millions of dollars)
	Revenues
	Commodity sales		$	—		$	—			$	10,549.20		$	—		$	10,549.20
	Services		—			—				1,320.10			—			1,320.10
	Total revenues		—			—				11,869.30			—			11,869.30
	Cost of sales and fuel		—			—				10,222.20			—			10,222.20
	Net margin		—			—				1,647.10			—			1,647.10
	Operating expenses
	Operations and maintenance		—			—				464.7			—			464.7
	Depreciation and amortization		—			—				236.7			—			236.7
	General taxes		—			—				56.9			—			56.9
	Total operating expenses		—			—				758.3			—			758.3
	Gain (loss) on sale of assets		—			—				11.9			—			11.9
	Operating income		—			—				900.7			—			900.7
	Equity earnings from investments		803.6			803.6				45.5			(1,542.2		)	110.5
	Allowance for equity funds used during construction		—			—				30.5			—			30.5
	Other income (expense), net		287.6			287.6				9.8			(575.2		)	9.8
	Interest expense		(287.6		)	(287.6		)		(236.7		)	575.2			(236.7		)
	Income before income taxes		803.6			803.6				749.8			(1,542.2		)	814.8
	Income taxes		—			—				(10.8		)	—			(10.8		)
	Net income		803.6			803.6				739			(1,542.2		)	804
	Less: Net income attributable to noncontrolling interests		—			—				0.4			—			0.4
	Net income attributable to ONEOK Partners, L.P.		$	803.6		$	803.6			$	738.6		$	(1,542.2	)	$	803.6
			Year Ended December 31, 2012
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
		(Millions of dollars)
Revenues
Commodity sales		$	—		$	—			$	9,010.20		$	—		$	9,010.20
Services		—			—				1,172.00			—			1,172.00
Total revenues		—			—				10,182.20			—			10,182.20
Cost of sales and fuel		—			—				8,540.40			—			8,540.40
Net margin		—			—				1,641.80			—			1,641.80
Operating expenses
Operations and maintenance		—			—				433			—			433
Depreciation and amortization		—			—				203.1			—			203.1
General taxes		—			—				49.5			—			49.5
Total operating expenses		—			—				685.6			—			685.6
Gain (loss) on sale of assets		—			—				6.7			—			6.7
Operating income		—			—				962.9			—			962.9
Equity earnings from investments		888			888				50.3			(1,703.3		)	123
Allowance for equity funds used during construction		—			—				13.6			—			13.6
Other income (expense), net		240.1			240.1				5			(480.2		)	5
Interest expense		(240.1		)	(240.1		)		(206.0		)	480.2			(206.0		)
Income before income taxes		888			888				825.8			(1,703.3		)	898.5
Income taxes		—			—				(10.1		)	—			(10.1		)
Net income		888			888				815.7			(1,703.3		)	888.4
Less: Net income attributable to noncontrolling interests		—			—				0.4			—			0.4
Net income attributable to ONEOK Partners, L.P.		$	888		$	888			$	815.3		$	(1,703.3	)	$	888
Condensed Consolidating Statements of Comprehensive Income
		Year Ended December 31, 2014
		Parent			Guarantor			Combined				Consolidating			Total
					Subsidiary			Non-Guarantor				Entries
								Subsidiaries
		(Millions of dollars)
Net income		$	910.3		$	910.3			$	841.5		$	(1,750.8	)	$	911.3
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives		(64.6		)	32.4				32.4			(64.8		)	(64.6		)
Realized (gains) losses on derivatives recognized in net income		31.6			21.1				21.1			(42.2		)	31.6
Total other comprehensive income (loss)		(33.0		)	53.5				53.5			(107.0		)	(33.0		)
Comprehensive income		877.3			963.8				895			(1,857.8		)	878.3
Less: Comprehensive income attributable to noncontrolling interests		—			—				1			—			1
Comprehensive income attributable to ONEOK Partners, L.P.		$	877.3		$	963.8			$	894		$	(1,857.8	)	$	877.3
		Year Ended December 31, 2013
		Parent			Guarantor			Combined				Consolidating			Total
					Subsidiary			Non-Guarantor				Entries
								Subsidiaries
		(Millions of dollars)
Net income		$	803.6		$	803.6			$	739		$	(1,542.2	)	$	804
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives		32.1			(14.5		)		(14.5		)	29			32.1
Realized (gains) losses on derivatives recognized in net income		8.4			(1.7		)		(1.7		)	3.4			8.4
Total other comprehensive income (loss)		40.5			(16.2		)		(16.2		)	32.4			40.5
Comprehensive income		844.1			787.4				722.8			(1,509.8		)	844.5
Less: Comprehensive income attributable to noncontrolling interests		—			—				0.4			—			0.4
Comprehensive income attributable to ONEOK Partners, L.P.		$	844.1		$	787.4			$	722.4		$	(1,509.8	)	$	844.1
		Year Ended December 31, 2012
		Parent			Guarantor			Combined				Consolidating			Total
					Subsidiary			Non-Guarantor				Entries
								Subsidiaries
		(Millions of dollars)
Net income		$	888		$	888			$	815.7		$	(1,703.3	)	$	888.4
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives		10.3			46.8				46.8			(93.6		)	10.3
Realized (gains) losses on derivatives recognized in net income		(58.5		)	(61.5		)		(61.5		)	123			(58.5		)
Total other comprehensive income (loss)		(48.2		)	(14.7		)		(14.7		)	29.4			(48.2		)
Comprehensive income		839.8			873.3				801			(1,673.9		)	840.2
Less: Comprehensive income attributable to noncontrolling interests		—			—				0.4			—			0.4
Comprehensive income attributable to ONEOK Partners, L.P.		$	839.8		$	873.3			$	800.6		$	(1,673.9	)	$	839.8
Condensed Consolidating Balance Sheets
		December 31, 2014
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
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				1,041.60			—			1,086.00
Property, plant and equipment
Property, plant and equipment		—			—				13,377.60			—			13,377.60
Accumulated depreciation and amortization		—			—				1,842.10			—			1,842.10
Net property, plant and equipment		—			—				11,535.50			—			11,535.50
Investments and other assets
Investments in unconsolidated affiliates		4,248.00			5,469.80				746.1			(9,331.3		)	1,132.60
Intercompany notes receivable		8,843.30			7,579.00				—			(16,422.3		)	—
Goodwill and intangible assets		—			—				822.4			—			822.4
Other assets		36.2			—				21.8			—			58
Total investments and other assets		13,127.50			13,048.80				1,590.30			(25,753.6		)	2,013.00
Total assets		$	13,129.40		$	13,091.30			$	14,167.40		$	(25,753.6	)	$	14,634.50
Liabilities and equity
Current liabilities
Current maturities of long-term debt		$	—		$	—			$	7.7		$	—		$	7.7
Notes payable		1,055.30			—				—			—			1,055.30
Accounts payable		—			—				874.7			—			874.7
Affiliate payables		—			—				36.1			—			36.1
Commodity imbalances		—			—				104.7			—			104.7
Accrued interest		92			—				—			—			92
Other current liabilities		44.8			—				120.8			—			165.6
Total current liabilities		1,192.10			—				1,144.00			—			2,336.10
Intercompany debt		—			8,843.30				7,579.00			(16,422.3		)	—
Long-term debt, excluding current maturities		5,986.50			—				51.9			—			6,038.40
Deferred credits and other liabilities		—			—				141.3			—			141.3
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries		5,950.80			4,248.00				5,083.30			(9,331.3		)	5,950.80
Noncontrolling interests in consolidated subsidiaries		—			—				167.9			—			167.9
Total equity		5,950.80			4,248.00				5,251.20			(9,331.3		)	6,118.70
Total liabilities and equity		$	13,129.40		$	13,091.30			$	14,167.40		$	(25,753.6	)	$	14,634.50
		December 31, 2013
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
Assets		(Millions of dollars)
Current assets
Cash and cash equivalents		$	—		$	134.5			$	—		$	—		$	134.5
Accounts receivable, net		—			—				1,103.10			—			1,103.10
Affiliate receivables		—			—				9.2			—			9.2
Natural gas and natural gas liquids in storage		—			—				188.3			—			188.3
Commodity imbalances		—			—				80.5			—			80.5
Materials and supplies		—			—				54.1			—			54.1
Other current assets		4.8			—				8.6			—			13.4
Total current assets		4.8			134.5				1,443.80			—			1,583.10
Property, plant and equipment
Property, plant and equipment		—			—				10,755.00			—			10,755.00
Accumulated depreciation and amortization		—			—				1,652.60			—			1,652.60
Net property, plant and equipment		—			—				9,102.40			—			9,102.40
Investments and other assets
Investments in unconsolidated affiliates		4,336.40			4,593.10				825.6			(8,525.3		)	1,229.80
Intercompany notes receivable		6,638.30			6,247.10				—			(12,885.4		)	—
Goodwill and intangible assets		—			—				832.2			—			832.2
Other assets		92.7			—				22.4			—			115.1
Total investments and other assets		11,067.40			10,840.20				1,680.20			(21,410.7		)	2,177.10
Total assets		$	11,072.20		$	10,974.70			$	12,226.40		$	(21,410.7	)	$	12,862.60
Liabilities and equity
Current liabilities
Current maturities of long-term debt		$	—		$	—			$	7.7		$	—		$	7.7
Notes payable		—			—				—			—			—
Accounts payable		—			—				1,255.40			—			1,255.40
Affiliate payables		—			—				47.5			—			47.5
Commodity imbalances		—			—				213.6			—			213.6
Accrued interest		92.7			—				—			—			92.7
Other current liabilities		—			—				89.1			—			89.1
Total current liabilities		92.7			—				1,613.30			—			1,706.00
Intercompany debt		—			6,638.30				6,247.10			(12,885.4		)	—
Long-term debt, excluding current maturities		5,985.30			—				59.6			—			6,044.90
Deferred credits and other liabilities		—			—				113			—			113
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries		4,994.20			4,336.40				4,188.90			(8,525.3		)	4,994.20
Noncontrolling interests in consolidated subsidiaries		—			—				4.5			—			4.5
Total equity		4,994.20			4,336.40				4,193.40			(8,525.3		)	4,998.70
Total liabilities and equity		$	11,072.20		$	10,974.70			$	12,226.40		$	(21,410.7	)	$	12,862.60
Condensed Consolidating Statements of Cash Flows
		Year Ended December 31, 2014
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
		(Millions of dollars)
Operating activities
Cash provided by operating activities		$	1,155.70		$	69.8			$	1,136.50		$	(1,052.2	)	$	1,309.80
Investing activities
Capital expenditures (less allowance for equity funds used during construction)		—			—				(1,746.0		)	—			(1,746.0		)
Cash paid for acquisitions, net of cash received		—			—				(814.9		)	—			(814.9		)
Contributions to unconsolidated affiliates		—			—				(1.0		)	—			(1.0		)
Distributions received from unconsolidated affiliates		—			17.7				3.4			—			21.1
Proceeds from sale of assets		—			—				7.8			—			7.8
Cash provided by (used in) investing activities		—			17.7				(2,550.7		)	—			(2,533.0		)
Financing activities
Cash distributions:
General and limited partners		(1,052.2		)	(1,052.2		)		—			1,052.20			(1,052.2		)
Noncontrolling interests		—			—				(0.6		)	—			(0.6		)
Intercompany borrowings (advances), net		(2,295.2		)	872.7				1,422.50			—			—
Borrowing (repayment) of notes payable, net		1,055.30			—				—			—			1,055.30
Repayment of long-term debt		—			—				(7.7		)	—			(7.7		)
Issuance of common units, net of issuance costs		1,113.10			—				—			—			1,113.10
Contribution from general partner		23.3			—				—			—			23.3
Cash provided by (used in) financing activities		(1,155.7		)	(179.5		)		1,414.20			1,052.20			1,131.20
Change in cash and cash equivalents		—			(92.0		)		—			—			(92.0		)
Cash and cash equivalents at beginning of period		—			134.5				—			—			134.5
Cash and cash equivalents at end of period		$	—		$	42.5			$	—		$	—		$	42.5
		Year Ended December 31, 2013
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
		(Millions of dollars)
Operating activities
Cash provided by operating activities		$	870.7		$	65.1			$	981.6		$	(909.7	)	$	1,007.70
Investing activities
Capital expenditures (less allowance for equity funds used during construction)		—			(2.6		)		(1,936.7		)	—			(1,939.3		)
Cash paid for acquisitions, net of cash received		—			—				(394.9		)	—			(394.9		)
Contributions to unconsolidated affiliates		—			(30.8		)		(4.5		)	—			(35.3		)
Distributions received from unconsolidated affiliates		—			19.4				11.7			—			31.1
Proceeds from sale of assets		—			—				12.3			—			12.3
Cash used in investing activities		—			(14.0		)		(2,312.1		)	—			(2,326.1		)
Financing activities
Cash distributions:
General and limited partners		(909.7		)	(909.7		)		—			909.7			(909.7		)
Noncontrolling interests		—			—				(0.6		)	—			(0.6		)
Intercompany borrowings (advances), net		(1,794.8		)	456				1,338.80			—			—
Issuance of long-term debt, net of discounts		1,247.80			—				—			—			1,247.80
Long-term debt financing costs		(10.2		)	—				—			—			(10.2		)
Repayment of long-term debt		—			—				(7.7		)	—			(7.7		)
Issuance of common units, net of issuance costs		583.9			—				—			—			583.9
Contribution from general partner		12.3			—				—			—			12.3
Cash provided by (used in) financing activities		(870.7		)	(453.7		)		1,330.50			909.7			915.8
Change in cash and cash equivalents		—			(402.6		)		—			—			(402.6		)
Cash and cash equivalents at beginning of period		—			537.1				—			—			537.1
Cash and cash equivalents at end of period		$	—		$	134.5			$	—		$	—		$	134.5
		Year Ended December 31, 2012
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
		(Millions of dollars)
Operating activities
Cash provided by operating activities		$	760.9		$	72.7			$	873.4		$	(760.9	)	$	946.1
Investing activities
Capital expenditures (less allowance for equity funds used during construction)		—			—				(1,560.5		)	—			(1,560.5		)
Contributions to unconsolidated affiliates		—			—				(30.8		)	—			(30.8		)
Distributions received from unconsolidated affiliates		—			23				12.3			—			35.3
Proceeds from sale of assets		—			—				10.8			—			10.8
Cash provided by (used in) investing activities		—			23				(1,568.2		)	—			(1,545.2		)
Financing activities
Cash distributions:
General and limited partners		(760.9		)	(760.9		)		—			760.9			(760.9		)
Noncontrolling interests		—			—				(0.8		)	—			(0.8		)
Issuance of long-term debt, net of discounts		1,295.00			—				—			—			1,295.00
Long-term debt financing costs		(9.6		)	—				—			—			(9.6		)
Intercompany borrowings (advances), net		(1,873.9		)	1,167.20				706.7			—			—
Repayment of long-term debt		(350.0		)	—				(11.1		)	—			(361.1		)
Issuance of common units, net of issuance costs		919.4			—				—			—			919.4
Contribution from general partner		19.1			—				—			—			19.1
Cash provided by (used in) financing activities		(760.9		)	406.3				694.8			760.9			1,101.10
Change in cash and cash equivalents		—			502				—			—			502
Cash and cash equivalents at beginning of period		—			35.1				—			—			35.1
Cash and cash equivalents at end of period		$	—		$	537.1			$	—		$	—		$	537.1

SUMMARY_OF_SIGNIFICANT_ACCOUNT1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Consolidation	Consolidation - Our consolidated financial statements include the accounts of ONEOK Partners and our subsidiaries over which we have control or are the primary beneficiary. All significant intercompany balances and transactions have been eliminated in consolidation.
	Investments in unconsolidated affiliates are accounted for using the equity method if we have the ability to exercise significant influence over operating and financial policies of our investee. Under this method, an investment is carried at its acquisition cost and adjusted each period for contributions made, distributions received and our share of the investee’s comprehensive income. For the investments we account for under the equity method, the premium or excess cost over underlying fair value of net assets is referred to as equity method goodwill. Impairment of equity investments is recorded when the impairments are other than temporary. These amounts are recorded as investments in unconsolidated affiliates on our accompanying Consolidated Balance Sheets.  See Note M for disclosures of our unconsolidated affiliates.
	Distributions paid to us from our unconsolidated affiliates are classified as operating activities on our Consolidated Statements of Cash Flows until the cumulative distributions exceed our proportionate share of income from the unconsolidated affiliate since the date of our initial investment.  The amount of cumulative distributions paid to us that exceeds our cumulative proportionate share of income in each period represents a return of investment and is classified as an investing activity on our Consolidated Statements of Cash Flows.
Use of Estimates	Use of Estimates - The preparation of our consolidated financial statements and related disclosures in accordance with GAAP requires us to make estimates and assumptions with respect to values or conditions that cannot be known with certainty that affect the reported amount of assets and liabilities, and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements.  These estimates and assumptions also affect the reported amounts of revenue and expenses during the reporting period.  Items that may be estimated include, but are not limited to, the economic useful life of assets, fair value of assets, liabilities and equity method investments, provisions for uncollectible accounts receivable, unbilled revenues and cost of goods sold, expenses for services received but for which no invoice has been received, the results of litigation and various other recorded or disclosed amounts.
	We evaluate these estimates on an ongoing basis using historical experience, consultation with experts and other methods we consider reasonable based on the particular circumstances.  Nevertheless, actual results may differ significantly from the estimates.  Any effects on our financial position or results of operations from revisions to these estimates are recorded in the period when the facts that give rise to the revision become known.
Fair Value Measurements	Fair Value Measurements - 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 groups 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 and LIBOR and other liquid money-market instrument rates. We also utilize internally developed basis curves that incorporate observable and unobservable market data. 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 internally developed basis curves that incorporate observable and unobservable market data, NGL price curves from broker quotes, 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 is not 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.
	See Note C for discussion of our fair value measurements.
Cash and Cash Equivalents	Cash and Cash Equivalents - Cash equivalents consist of highly liquid investments, which are readily convertible into cash and have original maturities of three months or less.
Revenue Recognition	Revenue Recognition - Our reportable segments recognize revenue when services are rendered or product is delivered.  Our Natural Gas Gathering and Processing segment records revenues when gas is processed in or transported through our facilities. Our Natural Gas Liquids segment records revenues based upon contracted services and actual volumes exchanged or stored under service agreements in the period services are provided.  A portion of our revenues for our Natural Gas Liquids segment and Natural Gas Pipelines segment are recognized based upon contracted capacity and contracted volumes transported and stored under service agreements in the period services are provided.
Accounts Receivable	Accounts Receivable - Accounts receivable represent valid claims against nonaffiliated customers for products sold or services rendered, net of allowances for doubtful accounts.  We assess the creditworthiness of our counterparties on an ongoing basis and require security, including prepayments and other forms of collateral, when appropriate.  Outstanding customer receivables are reviewed regularly for possible nonpayment indicators, and allowances for doubtful accounts are recorded based upon management’s estimate of collectability at each balance sheet date.  At December 31, 2014 and 2013, our allowance for doubtful accounts was not material.
Inventory	Inventory - The values of current natural gas and NGLs in storage are determined using the lower of weighted-average cost or market method.  Noncurrent natural gas and NGLs are classified as property and valued at cost.  Materials and supplies are valued at average cost.
Commodity Imbalances	Commodity Imbalances - Commodity imbalances represent amounts payable or receivable for NGL exchange contracts and natural gas pipeline imbalances and are valued at market prices.  Under the majority of our NGL exchange agreements, we physically receive volumes of unfractionated NGLs, including the risk of loss and legal title to such volumes, from the exchange counterparty.  In turn, we deliver NGL products back to the customer and charge them gathering and fractionation fees. To the extent that the volumes we receive under such agreements differ from those we deliver, we record a net exchange receivable or payable position with the counterparties.  These net exchange receivables and payables are settled with movements of NGL products rather than with cash.  Natural gas pipeline imbalances are settled in cash or in-kind, subject to the terms of the pipelines’ tariffs or by agreement.
Derivatives and Risk Management	Derivatives and Risk Management - We utilize derivatives to reduce our market risk exposure to commodity price and interest-rate fluctuations and to achieve more predictable cash flows.  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	-	Fair value not recorded	-	Change in fair value not recognized in earnings
	normal sales
	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	-	Effective portion of the gain or loss on the
			derivative instrument is reported initially as a		derivative instrument is reclassified out of
			component of accumulated other		accumulated other comprehensive income (loss)
			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	-	Change in fair value of the hedged item is
			recorded as an adjustment to book value		recognized in earnings
	To reduce our exposure to fluctuations in natural gas, NGLs and condensate prices, we periodically enter into futures, forward sales 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 cash flow. We formally document all relationships between hedging instruments and hedged items, as well as risk-management objectives, 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.
	See Notes C and D for more discussion of our fair value measurements and risk management and hedging activities using derivatives.
Property, Plant and Equipment	Property, Plant and Equipment - Our properties are stated at cost, including AFUDC.  Generally, the cost of regulated property retired or sold, plus removal costs, less salvage, is charged to accumulated depreciation.  Gains and losses from sales or transfers of nonregulated properties or an entire operating unit or system of our regulated properties are recognized in income. Maintenance and repairs are charged directly to expense.
	The interest portion of AFUDC represents the cost of borrowed funds used to finance construction activities.  We capitalize interest costs during the construction or upgrade of qualifying assets.  Capitalized interest is recorded as a reduction to interest expense. The equity portion of AFUDC represents the capitalization of the estimated average cost of equity used during the construction of major projects and is recorded in the cost of our regulated properties and as a credit to the allowance for equity funds used during construction.
	Our properties are depreciated using the straight-line method over their estimated useful lives.  Generally, we apply composite depreciation rates to functional groups of property having similar economic circumstances.  We periodically conduct depreciation studies to assess the economic lives of our assets.  For our regulated assets, these depreciation studies are completed as a part of our rate proceedings or tariff filings, and the changes in economic lives, if applicable, are implemented prospectively when the new rates are billed.  For our nonregulated assets, if it is determined that the estimated economic life changes, the changes are made prospectively.  Changes in the estimated economic lives of our property, plant and equipment could have a material effect on our financial position or results of operations.
	Property, plant and equipment on our Consolidated Balance Sheets includes construction work in process for capital projects that have not yet been placed in service and therefore are not being depreciated.  Assets are transferred out of construction work in process when they are substantially complete and ready for their intended use.
	See Note E for disclosures of our property, plant and equipment.
Impairment of Goodwill and Long-Lived Assets, including Intangible Assets	Impairment of Goodwill and Long-Lived Assets, Including Intangible Assets - We assess our goodwill for impairment at least annually as of July 1.  Our goodwill impairment analysis performed as of July 1, 2014, did not result in an impairment charge nor did our analysis reflect any reporting units at risk, and subsequent to that date, no event has occurred indicating that the implied fair value of each of our reporting units (including its inherent goodwill) is less than the carrying value of its net assets. There were also no impairment charges resulting from our 2013 or 2012 impairment tests.
	As part of our impairment test, we first assess qualitative factors (including macroeconomic conditions, industry and market considerations, cost factors and overall financial performance) to determine whether it is more likely than not that the fair value of each of our reporting units is less than its carrying amount. If further testing is necessary, we perform a two-step impairment test for goodwill. In the first step, an initial assessment is made by comparing the fair value of a reporting unit with its book value, including goodwill.  If the fair value is less than the book value, an impairment is indicated, and we must perform a second test to measure the amount of the impairment. In the second test, we calculate the implied fair value of the goodwill by deducting the fair value of all tangible and intangible net assets of the reporting unit from the fair value determined in step one of the assessment. If the carrying value of the goodwill exceeds the implied fair value of the goodwill, we will record an impairment charge.
	To estimate the fair value of our reporting units, we use two generally accepted valuation approaches, an income approach and a market approach, using assumptions consistent with a market participant’s perspective.  Under the income approach, we use anticipated cash flows over a period of years plus a terminal value and discount these amounts to their present value using appropriate discount rates.  Under the market approach, we apply EBITDA multiples to forecasted EBITDA.  The multiples used are consistent with historical asset transactions.  The forecasted cash flows are based on average forecasted cash flows for a reporting unit over a period of years.
	We assess our long-lived assets, including intangible assets with finite useful lives, for impairment whenever events or changes in circumstances indicate that an asset’s carrying amount may not be recoverable.  An impairment is indicated if the carrying amount of a long-lived asset exceeds the sum of the undiscounted future cash flows expected to result from the use and eventual disposition of the asset.  If an impairment is indicated, we record an impairment loss equal to the difference between the carrying value and the fair value of the long-lived asset.  We determined that there were no asset impairments in 2014, 2013 or 2012.
	For the investments we account for under the equity method, the impairment test considers whether the fair value of the equity investment as a whole, not the underlying net assets, has declined and whether that decline is other than temporary.  Therefore, we periodically reevaluate the amount at which we carry our equity method investments to determine whether current events or circumstances warrant adjustments to our carrying value.
	See Notes E, F and M for our long-lived assets, goodwill and intangible assets and unconsolidated affiliates disclosures.
Regulation	Regulation - Our intrastate natural gas transmission pipelines are subject to the rate regulation and accounting requirements of the OCC, KCC, RRC and various municipalities in Texas.  Our interstate natural gas and natural gas liquids pipelines are subject to regulation by the FERC.  In Kansas and Texas, natural gas storage may be regulated by the state and the FERC for certain types of services.  Accordingly, portions of our Natural Gas Liquids and Natural Gas Pipelines segments follow the accounting and reporting guidance for regulated operations.  During the rate-making process for certain of our assets, regulatory authorities set the framework for what we can charge customers for our services and establish the manner that our costs are accounted for, including allowing us to defer recognition of certain costs and permitting recovery of the amounts through rates over time as opposed to expensing such costs as incurred. Certain examples of types of regulatory guidance include costs for fuel and losses, acquisition costs, contributions in aid of construction, charges for depreciation, and gains or losses on disposition of assets.  This allows us to stabilize rates over time rather than passing such costs on to the customer for immediate recovery.  Actions by regulatory authorities could have an effect on the amount recovered from rate payers.  Any difference in the amount recoverable and the amount deferred is recorded as income or expense at the time of the regulatory action.  A write-off of regulatory assets and costs not recovered may be required if all or a portion of the regulated operations have rates that are no longer:
	•	established by independent, third-party regulators;
	•	designed to recover the specific entity’s costs of providing regulated services; and
	•	set at levels that will recover our costs when considering the demand and competition for our services.
	At December 31, 2014 and 2013, we recorded regulatory assets of approximately $6.1 million and $6.8 million, respectively, which are currently being recovered and are expected to be recovered from our customers.  Regulatory assets are being recovered as a result of approved rate proceedings over varying time periods up to 40 years.  These assets are reflected in other assets on our Consolidated Balance Sheets.
Income Taxes	Income Taxes - We are not a taxable entity for federal income tax purposes.  As such, we do not directly pay federal income tax. Our taxable income or loss, which may vary substantially from the net income or loss reported in our Consolidated Statements of Income, is included in the federal income tax returns of each partner.  The aggregate difference in the basis of our net assets for financial and income tax purposes cannot be readily determined, as we do not have access to all information about each partner’s tax attributes related to us.
	Our corporate subsidiaries are required to pay federal and state income taxes.  Deferred income taxes are provided for the difference between the financial statement and income tax basis of assets and liabilities and carryforward items based on income tax laws and rates existing at the time the temporary differences are expected to reverse.  Except for the regulated companies, the effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date of the rate change.  For regulated companies, the effect on deferred tax assets and liabilities of a change in tax rates is recorded as regulatory assets and regulatory liabilities in the period that includes the enactment date, if, as a result of an action by a regulator, it is probable that the effect of the change in tax rates will be recovered from or returned to customers through future rates.
	We utilize a more-likely-than-not recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position that is taken or expected to be taken in a tax return.  We reflect penalties and interest as part of income tax expense as they become applicable for tax provisions that do not meet the more-likely-than-not recognition threshold and measurement attribute.  During 2014, 2013 and 2012, our tax positions did not require an establishment of a material reserve.
	We file numerous consolidated and separate income tax returns with federal tax authorities of the United States and Canada along with the tax authorities of several states.  There are no United States federal audits or statute waivers at this time. See Note L for additional discussion of income taxes.
Asset Retirement Obligations	Asset Retirement Obligations - Asset retirement obligations represent legal obligations associated with the retirement of long-lived assets that result from the acquisition, construction, development and/or normal use of the asset.  Certain of our natural gas gathering and processing facilities, and our natural gas liquids and pipeline facilities are subject to agreements or regulations that give rise to our asset retirement obligations for removal or other disposition costs associated with retiring the assets in place upon the discontinued use of the assets.  We recognize the fair value of a liability for an asset retirement obligation in the period when it is incurred if a reasonable estimate of the fair value can be made.  We are not able to estimate reasonably the fair value of the asset retirement obligations for portions of our assets, primarily certain pipeline assets, because the settlement dates are indeterminable given our expected continued use of the assets with proper maintenance. We expect our pipeline assets, for which we are unable to estimate reasonably the fair value of the asset retirement obligation, will continue in operation as long as supply and demand for natural gas and natural gas liquids exists. Based on the widespread use of natural gas for heating and cooking activities for residential users and electric-power generation for commercial users, as well as use of natural gas liquids by the petrochemical industry, we expect supply and demand to exist for the foreseeable future.
	For our assets that we are able to make an estimate, the fair value of the liability is added to the carrying amount of the associated asset, and this additional carrying amount is depreciated over the life of the asset.  The liability is accreted at the end of each period through charges to operating expense.  If the obligation is settled for an amount other than the carrying amount of the liability, we will recognize a gain or loss on settlement.  The depreciation and accretion expense are immaterial to our consolidated financial statements.
	In accordance with long-standing regulatory treatment, we collect, through rates, the estimated costs of removal on certain regulated properties through depreciation expense, with a corresponding credit to accumulated depreciation and amortization. These removal costs collected through rates include legal and nonlegal removal obligations; however, the amounts collected in excess of the asset removal costs incurred are accounted for as a regulatory liability for financial reporting purposes. Historically, the regulatory authorities that have jurisdiction over our regulated operations have not required us to quantify this amount; rather, these costs are addressed prospectively in depreciation rates and are set in each general rate order.  We have made an estimate of our regulatory liability using current rates since the last general rate order in each of our jurisdictions; however, for financial reporting purposes, significant uncertainty exists regarding the ultimate disposition of this regulatory liability pending, among other issues, clarification of regulatory intent.  We continue to monitor regulatory requirements, and the liability may be adjusted as more information is obtained.
Contingencies	Contingencies - Our accounting for contingencies covers a variety of business activities, including contingencies for legal and environmental exposures.  We accrue these contingencies when our assessments indicate that it is probable that a liability has been incurred or an asset will not be recovered and an amount can be estimated reasonably.  We expense legal fees as incurred and base our legal liability estimates on currently available facts and our estimates of the ultimate outcome or resolution. Accruals for estimated losses from environmental remediation obligations generally are recognized no later than completion of a remediation feasibility study.  Recoveries of environmental remediation costs from other parties are recorded as assets when their receipt is deemed probable.  Our expenditures for environmental evaluation, mitigation, remediation and compliance to date have not been significant in relation to our financial position or results of operations, and our expenditures related to environmental matters had no material effect on earnings or cash flows during 2014, 2013 and 2012. Actual results may differ from our estimates resulting in an impact, positive or negative, on earnings.  See Note O for additional discussion of contingencies.
Accounting Standards Update 2015-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [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 will adopt this guidance in the first quarter 2016, and we are evaluating the impact on us.
Accounting Standards Update 2014-17 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In November 2014, the FASB issued ASU 2014-17, “Business Combination (Topic 805): Pushdown Accounting,” which provides an acquired entity with an option to apply pushdown accounting in its separate financial statements when a change-in-control event occurs. An acquired entity may elect the option to apply pushdown accounting in the reporting period in which the change-in-control event occurs. The standard applies to all entities and was effective on November 18, 2014. We adopted this guidance beginning in the fourth quarter 2014, and we do not expect it to materially impact us.
Accounting Standards Update 2014-15 [Member]
New Accounting Pronouncements or Change in Accounting Principle [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 will adopt this guidance beginning in the first quarter 2016, and we do not expect it to materially impact us.
Accounting Standards Update 2014-08 [Member]
New Accounting Pronouncements or Change in Accounting Principle [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 will adopt 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 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [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. This update will be effective for interim and annual periods that begin on or after December 15, 2016, with either retrospective application for all periods presented or retrospective application with a cumulative effect adjustment. We will adopt this guidance beginning in the first quarter 2017, and we are evaluating the impact on us.

ACQUISITIONS_Policies

ACQUISITIONS (Policies)	12 Months Ended
	Dec. 31, 2014
Sage Creek Acquisition [Member]
Business Acquisition [Line Items]
Business Combinations Policy [Policy Text Block]	This acquisition was accounted for as a business combination. The excess of cost over those fair values was recorded as goodwill.
West Texas LPG Acquisition [Member]
Business Acquisition [Line Items]
Business Combinations Policy [Policy Text Block]	We accounted for the West Texas LPG acquisition as a business combination which, among other things, requires assets acquired and liabilities assumed to be measured at their acquisition-date fair values.

LONGTERM_DEBT_LONGTERM_DEBT_Po

LONG-TERM DEBT LONG-TERM DEBT (Policies)	12 Months Ended
	Dec. 31, 2014
Debt Policy [Abstract]
Debt Policy	We amortize premiums, discounts and expenses incurred in connection with the issuance of long-term debt consistent with the terms of the respective debt instrument.

EQUITY_EQUITY_Policies

EQUITY EQUITY (Policies)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
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.

SEGMENTS_Segment_Accounting_Po

SEGMENTS Segment Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Segment Accounting Policy [Text Block]	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.  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 called ONE Gas on January 31, 2014, transactions with ONE Gas subsequent to the separation are reflected as sales to unaffiliated customers.

ACQUISITIONS_Tables

ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2014
Sage Creek Acquisition [Member]
Business Acquisition [Line Items]
Schedule of Purchase Price Allocation [Table Text Block]	The purchase price and assessment of the fair value of the assets acquired were as follows:
		Natural Gas			Natural Gas		Total
		Gathering and			Liquids
		Processing
	Property, plant and equipment	(Thousands of dollars)
	Gathering pipelines and related equipment	$	41,129		$	18,045	$	59,174
	Processing and fractionation and related equipment	50,595			—		50,595
	General plant and other	120			—		120
	Intangible assets	40,000			63,000		103,000
	Identifiable assets acquired	131,844			81,045		212,889
	Goodwill	20,000			72,000		92,000
	Total purchase price	$	151,844		$	153,045	$	304,889
West Texas LPG Acquisition [Member]
Business Acquisition [Line Items]
Schedule of Purchase Price Allocation [Table Text Block]	The preliminary purchase price allocation and assessment of the fair value of the assets acquired as of the acquisition date were as follows (in thousands):
	Cash	$	13,839
	Accounts receivable	9,132
	Other current assets	3,369
	Property, plant and equipment
	Regulated	807,601
	Nonregulated	153,919
	Total property, plant and equipment	961,520
	Total fair value of assets acquired	987,860
	Accounts payable	(8,621		)
	Other current liabilities	(1,553		)
	Total fair value of liabilities acquired	(10,174		)
	Less: fair value of noncontrolling interest	(162,913		)
	Net assets acquired	814,773
	Less: cash received	(13,839		)
	Net cash paid for acquisition	$	800,934

FAIR_VALUE_MEASUREMENTS_Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
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:
		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 posted no cash collateral.
	(b) - Included in other current assets, other assets or other current liabilities in our Consolidated Balance Sheets.
		December 31, 2013
		Level 1			Level 2			Level 3			Total - Gross			Netting (a)			Total - Net (b)
		(Thousands of dollars)
	Derivative assets
	Commodity contracts
	Financial contracts	$	—		$	3,657		$	2,812		$	6,469		$	(1,746	)	$	4,723
	Physical contracts	—			—			2,023			2,023			(946		)	1,077
	Interest-rate contracts	—			54,503			—			54,503			—			54,503
	Total derivative assets	$	—		$	58,160		$	4,835		$	62,995		$	(2,692	)	$	60,303
	Derivative liabilities
	Commodity contracts
	Financial contracts	$	—		$	(2,953	)	$	(2,154	)	$	(5,107	)	$	1,746		$	(3,361	)
	Physical contracts	—			—			(3,463		)	(3,463		)	946			(2,517		)
	Total derivative liabilities	$	—		$	(2,953	)	$	(5,617	)	$	(8,570	)	$	2,692		$	(5,878	)
	(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, 2013, we had no cash collateral held or 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:
		Years Ended December 31,
	Derivative Assets (Liabilities)	2014			2013
		(Thousands of dollars)
	Net assets (liabilities) at beginning of period	$	(782	)	$	(2,423	)
	Total realized/unrealized gains (losses):
	Included in earnings (a)	(927		)	959
	Included in other comprehensive income (loss)	7,260			682
	Purchases, issuances and settlements	3,734			—
	Net assets (liabilities) at end of period	$	9,285		$	(782	)
	Total gains (losses) for the period included in earnings	$	31		$	959
	attributable to the change in unrealized gains (losses)
	relating to assets and liabilities still held as of the end
	of the period (a)

RISK_MANAGEMENT_AND_HEDGING_AC1

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position	Fair Values of Derivative Instruments - See Note A 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:
			December 31, 2014								December 31, 2013
			Assets (a)				(Liabilities) (a)				Assets (a)				(Liabilities) (a)
			(Thousands of dollars)
	Derivatives designated as hedging instruments
	Commodity contracts
	Financial contracts		$	43,234			$	(1,137	)		$	6,469			$	(5,107	)
	Physical contracts		9,922				—				1,064				(3,463		)
	Interest-rate contracts		2,288				(44,843		)		54,503				—
	Total derivatives designated as hedging instruments		55,444				(45,980		)		62,036				(8,570		)
	Derivatives not designated as hedging instruments
	Commodity contracts
	Physical contracts		—				(23		)		959				—
	Total derivatives not designated as hedging instruments		—				(23		)		959				—
	Total derivatives		$	55,444			$	(46,003	)		$	62,995			$	(8,570	)
	(a) - Included on a net basis in other current assets, other assets or other current liabilities on our Consolidated Balance Sheets.
Schedule of Notional Quantities for Derivative Instruments	Notional Quantities for Derivative Instruments - The following table sets forth the notional quantities for derivative instruments held for the periods indicated:
				December 31, 2014								December 31, 2013
		Contract		Purchased/				Sold/				Purchased/				Sold/
		Type		Payor				Receiver				Payor				Receiver
	Derivatives designated as hedging instruments:
	Cash flow hedges
	Fixed price
	-Natural gas (Bcf)	Futures and swaps		—				(41.2		)		—				(48.1		)
	-Crude oil and NGLs (MMBbl)	Futures, forwards and swaps		—				(0.5		)		—				(4.0		)
	Basis
	-Natural gas (Bcf)	Futures and swaps		—				(41.2		)		—				(48.1		)
	Interest-rate contracts (Millions of dollars)	Forward-starting		$	900			$	—			$	400			$	—
		swaps
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 loss for the periods indicated:
	Derivatives in Cash Flow Hedging Relationships		Years Ended December 31,
			2014				2013				2012
			(Thousands of dollars)
	Commodity contracts		$	32,354			$	(14,475	)		$	46,804
	Interest-rate contracts		(96,993		)		46,616				(36,509		)
	Total unrealized gain (loss) recognized in other comprehensive loss on derivatives(effective portion)		$	(64,639	)		$	32,141			$	10,295
Schedule of Derivative Instruments, Gain (loss) of Statement of Financial Performance	The following table sets forth the effect of cash flow hedges on our Consolidated Statements of Income for the periods indicated:
	Derivatives in Cash Flow		Location of Gain (Loss) Reclassified from
	Hedging Relationships		Accumulated Other Comprehensive Loss into		Years Ended December 31,
			Net Income (Effective Portion)		2014				2013				2012
					(Thousands of dollars)
	Commodity contracts		Commodity sales revenues		$	(21,052	)		$	1,689			$	61,526
	Interest-rate contracts		Interest expense		(10,601		)		(10,033		)		(2,997		)
	Total gain (loss) reclassified from accumulated other comprehensive loss				$	(31,653	)		$	(8,344	)		$	58,529
	into net income on derivatives (effective portion)

PROPERTY_PLANT_AND_EQUIPMENT_T

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment by Property Type	The following table sets forth our property, plant and equipment by property type, for the periods indicated:
		Estimated Useful	December 31,			December 31,
		Lives (Years)	2014			2013
			(Thousands of dollars)
	Nonregulated
	Gathering pipelines and related equipment	5 to 40	$	2,449,343		$	2,173,271
	Processing and fractionation and related equipment	3 to 40	2,880,572			2,295,983
	Storage and related equipment	5 to 54	478,276			362,704
	Transmission pipelines and related equipment	5 to 54	518,585			302,718
	General plant and other	2 to 60	142,276			116,468
	Construction work in process	—	1,233,808			1,068,428
	Regulated
	Storage and related equipment	5 to 54	115,799			135,922
	Natural gas transmission pipelines and related equipment	5 to 77	1,478,035			1,420,517
	Natural gas liquids transmission pipelines and related equipment	5 to 80	3,822,799			2,049,461
	General plant and other	2 to 53	63,424			53,315
	Construction work in process	—	194,700			776,261
	Property, plant and equipment		13,377,617			10,755,048
	Accumulated depreciation and amortization - nonregulated		(1,123,261		)	(1,004,614		)
	Accumulated depreciation and amortization - regulated		(718,823		)	(648,034		)
	Net property, plant and equipment		$	11,535,533		$	9,102,400
Average Depreciation Rates for Regulated Property	The average depreciation rates for our regulated property are set forth, by segment, in the following table for the periods indicated:
		Years Ended December 31,
		2014	2013		2012
	Natural Gas Liquids	2.00%	2.00%		1.90%
	Natural Gas Pipelines	2.10%	2.20%		2.20%

GOODWILL_AND_INTANGIBLE_ASSETS1

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill by Segment	Goodwill - The following table sets forth our goodwill, by segment, for the periods indicated:
		December 31,				December 31,
		2014				2013
		(Thousands of dollars)
	Natural Gas Gathering and Processing	$	112,141			$	112,141
	Natural Gas Liquids	247,566				247,566
	Natural Gas Pipelines	129,011				129,011
	Total goodwill	$	488,718			$	488,718
Gross Carrying Amount and Accumulated Amortization of Intangible Assets	The following table reflects the gross carrying amount and accumulated amortization of intangible assets for the periods presented:
			December 31,				December 31,
			2014				2013
			(Thousands of dollars)
	Gross intangible assets		$	411,650			$	409,650
	Accumulated amortization		(78,010		)		(66,188		)
	Net intangible assets		$	333,640			$	343,462

LONGTERM_DEBT_Tables

LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2014
Long-term Debt, Unclassified [Abstract]
Long-term debt	The following table sets forth our long-term debt for the periods indicated:
		December 31,			December 31,
		2014			2013
		(Thousands of dollars)
	ONEOK Partners
	$650,000 at 3.25% due 2016	$	650,000		$	650,000
	$450,000 at 6.15% due 2016	450,000			450,000
	$400,000 at 2.0% due 2017	400,000			400,000
	$425,000 at 3.2% due 2018	425,000			425,000
	$500,000 at 8.625% due 2019	500,000			500,000
	$900,000 at 3.375 % due 2022	900,000			900,000
	$425,000 at 5.0 % due 2023	425,000			425,000
	$600,000 at 6.65% due 2036	600,000			600,000
	$600,000 at 6.85% due 2037	600,000			600,000
	$650,000 at 6.125% due 2041	650,000			650,000
	$400,000 at 6.2% due 2043	400,000			400,000
	Guardian Pipeline
	Average 7.88% due 2022	59,557			67,208
	Total long-term notes payable	6,059,557			6,067,208
	Unamortized debt discount and other	(13,528		)	(14,691		)
	Current maturities	(7,650		)	(7,650		)
	Long-term debt	$	6,038,379		$	6,044,867
Aggregate maturities of long-term debt outstanding	The aggregate maturities of long-term debt outstanding for years 2015 through 2019 are shown below:
		ONEOK			Guardian			Total
		Partners			Pipeline
		(Millions of dollars)
	2015	$	—		$	7.7		$	7.7
	2016	$	1,100.00		$	7.7		$	1,107.70
	2017	$	400		$	7.7		$	407.7
	2018	$	425		$	7.7		$	432.7
	2019	$	500		$	7.7		$	507.7

EQUITY_Tables

EQUITY (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Quarterly cash distribution declared and paid on common and Class B units	Cash Distributions - The following table sets forth the quarterly cash distribution declared and paid on each of our common and Class B units during the periods indicated:
	Declared for	Distribution		Date Declared		Date Paid
	Quarter Ending	Per Unit
	December 31, 2014	$	0.79	January 15, 2015		February 13, 2015
	September 30, 2014	$	0.775	October 23, 2014		November 14, 2014
	June 30, 2014	$	0.76	July 25, 2014		August 14, 2014
	March 31, 2014	$	0.745	April 18, 2014		May 15, 2014
	December 31, 2013	$	0.73	January 16, 2014		February 14, 2014
	September 30, 2013	$	0.725	October 23, 2013		November 14, 2013
	June 30, 2013	$	0.72	July 25, 2013		August 15, 2013
	March 31, 2013	$	0.715	April 18, 2013		May 15, 2013
	December 31, 2012	$	0.71	January 17, 2013		February 14, 2013
	30-Sep-12	$	0.685	24-Oct-12		14-Nov-12
	30-Jun-12	$	0.66	26-Jul-12		15-Aug-12
	31-Mar-12	$	0.635	19-Apr-12		15-May-12
	31-Dec-11	$	0.61	19-Jan-12		14-Feb-12
Schedule of distributions made to general or limited partner	The following table shows our distributions paid during the periods indicated:
		Years Ended December 31,
		2014		2013			2012
		(Thousands, except per unit amounts)
	Distribution per unit	$	3.01	$	2.87		$	2.59
	General partner distributions	$	21,044	$	18,193		$	15,217
	Incentive distributions	304,999		251,664			186,130
	Distributions to general partner	326,043		269,857			201,347
	Limited partner distributions to ONEOK	279,292		266,302			235,442
	Limited partner distributions to other unitholders	446,910		373,554			324,123
	Total distributions paid	$	1,052,245	$	909,713		$	760,912
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:
		Years Ended December 31,
		2014		2013			2012
		(Thousands, except per unit amounts)
	Distribution per unit	$	3.07	$	2.89		$	2.69
	General partner distributions	$	22,109	$	18,625		$	16,355
	Incentive distributions	326,022		259,466			210,095
	Distributions to general partner	348,131		278,091			226,450
	Limited partner distributions to ONEOK	284,860		268,157			249,600
	Limited partner distributions to other unitholders	472,466		384,988			341,704
	Total distributions declared	$	1,105,457	$	931,236		$	817,754

ACCUMULATED_OTHER_COMPREHENSIV1

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	12 Months Ended
	Dec. 31, 2014
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table sets forth the balance in accumulated other comprehensive income (loss) for the periods indicated:
		Accumulated
		Other
		Comprehensive
		Loss (a)
		(Thousands of dollars)
	1-Jan-13	$	(99,322	)
	Other comprehensive income (loss) before reclassifications	32,141
	Amounts reclassified from accumulated other comprehensive income (loss)	8,344
	Net current-period other comprehensive income (loss) attributable to ONEOK Partners	40,485
	31-Dec-13	(58,837		)
	Other comprehensive income (loss) before reclassifications	(64,639		)
	Amounts reclassified from accumulated other comprehensive income (loss)	31,653
	Net current-period other comprehensive income (loss) attributable to ONEOK Partners	(32,986		)
	31-Dec-14	$	(91,823	)
	(a) All amounts are attributable to unrealized gains (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	Year Ended December 31,						Affected Line Item in the
	Comprehensive Income (Loss) Components	2014			2013			Consolidated Statements of Income
		(Thousands of dollars)
	Unrealized (gains) losses on risk-management assets/liabilities
	Commodity contracts	$	21,052		$	(1,689	)	Commodity sales revenues
	Interest-rate contracts	10,601			10,033			Interest expense
	Total reclassifications for the period attributable to ONEOK Partners	$	31,653		$	8,344		Net income attributable to ONEOK Partners

INCOME_TAXES_Tables

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Provision for Income Taxes	The following table sets forth our provision for income taxes for the periods indicated:
		Years Ended December 31,
		2014			2013			2012
		(Thousands of dollars)
	Current income tax provision
	Federal	$	59		$	56		$	(156	)
	State	1,777			5,358			3,446
	Total current income tax provision	1,836			5,414			3,290
	Deferred income tax provision
	Federal	5,033			4,303			6,330
	State	5,799			1,141			485
	Total deferred income tax provision	10,832			5,444			6,815
	Total provision for income taxes	$	12,668		$	10,858		$	10,105
Reconciliation of Income Tax Provision	The following table is a reconciliation of our income tax provision for the periods indicated:
		Years Ended December 31,
		2014			2013			2012
		(Thousands of dollars)
	Income before income taxes	$	924,003		$	814,841		$	898,533
	Less: Net income attributable to noncontrolling interests	1,037			357			438
	Income attributable to ONEOK Partners, L.P. before income taxes	922,966			814,484			898,095
	Federal statutory income tax rate	35		%	35		%	35		%
	Provision for federal income taxes	323,038			285,069			314,333
	Partnership earnings not subject to tax	(318,021		)	(280,992		)	(307,839		)
	State income taxes, net of federal benefit	7,576			6,095			4,530
	Other, net	75			686			(919		)
	Income tax provision	$	12,668		$	10,858		$	10,105
Schedule of Deferred Tax Assets and Liabilities	The following table sets forth the tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and liabilities for the periods indicated. The prior period has been recast to conform to the current year presentation.
		Years Ended December 31,
		2014			2013
		(Thousands of dollars)
	Deferred tax assets
	Federal and state net operating loss	$	3,179		$	1,410
	Other	1,626			1,521
	Total deferred tax assets	4,805			2,931
	Deferred tax liabilities
	Excess of tax over book depreciation	61,120			48,433
	Regulatory assets	1,962			1,978
	Total deferred tax liabilities	63,082			50,411
	Net deferred tax liabilities	$	58,277		$	47,480

UNCONSOLIDATED_AFFILIATES_Tabl

UNCONSOLIDATED AFFILIATES (Tables)	12 Months Ended
	Dec. 31, 2014
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Equity Method Investments	Investments in Unconsolidated Affiliates - The following table sets forth our investments in unconsolidated affiliates for the periods indicated:
		Net		December 31,				December 31,
		Ownership		2014				2013
		Interest
				(Thousands of dollars)
	Northern Border Pipeline	50%		$	387,253			$	404,803
	Overland Pass Pipeline Company	50%		466,977				466,671
	Fort Union Gas Gathering	37%		127,876				125,220
	Bighorn Gas Gathering	49%		7,924				87,837
	Other	Various		142,623				145,307
	Investments in unconsolidated affiliates (a)			$	1,132,653			$	1,229,838
	(a) - Equity method goodwill (Note A) was $170.9 million and $224.3 million at December 31, 2014 and 2013, respectively.
Equity Earnings from Investments	Equity Earnings from Investments - The following table sets forth our equity earnings from investments for the periods indicated:
		Years Ended December 31,
		2014				2013				2012
		(Thousands of dollars)
	Share of investee earnings (loss)
	Northern Border Pipeline	$	69,819			$	65,046			$	72,705
	Overland Pass Pipeline Company	25,906				20,461				20,043
	Fort Union Gas Gathering	16,619				15,826				17,218
	Bighorn Gas Gathering (a)	(25,621		)		1,952				3,820
	Other	7,701				7,232				9,238
	Total share of investee earnings	$	94,424			$	110,517			$	123,024
	Impairment of investment in Bighorn Gas Gathering	(53,421		)		—				—
	Equity earnings from investments	$	41,003			$	110,517			$	123,024
	(a) Includes proportionate share of investee impairment of long-lived assets charge of $23.0 million in 2014.
Unconsolidated Affiliates Financial Information	Unconsolidated Affiliates Financial Information - The following tables set forth summarized combined financial information of our unconsolidated affiliates for the periods indicated:
		December 31,				December 31,
		2014				2013
		(Thousands of dollars)
	Balance Sheet
	Current assets	$	153,293			$	155,310
	Property, plant and equipment, net	$	2,440,714			$	2,557,571
	Other noncurrent assets	$	35,668			$	34,478
	Current liabilities	$	95,026			$	98,967
	Long-term debt	$	428,385			$	442,103
	Other noncurrent liabilities	$	73,767			$	58,221
	Accumulated other comprehensive loss	$	(2,063	)		$	(2,291	)
	Owners’ equity	$	2,034,560			$	2,150,359
		Years Ended December 31,
		2014				2013				2012
		(Thousands of dollars)
	Income Statement
	Operating revenues	$	548,491			$	528,665			$	573,197
	Operating expenses (a)	$	309,990			$	256,292			$	269,858
	Net income (a)	$	214,410			$	248,998			$	279,766
	Distributions paid to us	$	139,019			$	137,498			$	155,741
	(a) Includes long-lived asset impairment charge on Bighorn Gas Gathering in 2014.

RELATEDPARTY_TRANSACTIONS_Tabl

RELATED-PARTY TRANSACTIONS (Tables)	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Transactions with related parties	The following table sets forth the transactions with related parties for the periods indicated:
		Years Ended December 31,
		2014		2013		2012
		(Thousands of dollars)
	Revenues	$	53,526	$	340,743	$	352,099
	Expenses
	Cost of sales and fuel	$	10,835	$	37,963	$	33,094
	Administrative and general expenses	330,541		265,448		246,050
	Total expenses	$	341,376	$	303,411	$	279,144

COMMITMENTS_AND_CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Rental Payments for Firm Transportation and Storage Contracts	The following table sets forth our firm transportation and storage contract payments for the periods presented:
		Firm
		Transportation
		and Storage
		Contracts
		(Millions of dollars)
	2015	$	33.6
	2016	32.1
	2017	30.4
	2018	29.4
	2019	28.8
	Thereafter	68.5
	Total	$	222.8

SEGMENTS_Tables

SEGMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Selected Financial Information by Reportable Segment	Operating Segment Information - The following tables set forth certain selected financial information for our operating segments for the periods indicated:
	Year Ended December 31, 2014	Natural Gas			Natural Gas			Natural Gas		Other and			Total
		Gathering and			Liquids (a)			Pipelines (b)		Eliminations
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	1,478,729		$	10,329,609		$	329,801	$	—		$	12,138,139
	Sales to affiliated customers	41,214			—			12,312		—			53,526
	Intersegment revenues	1,447,665			215,772			8,343		(1,671,780		)	—
	Total revenues	$	2,967,608		$	10,545,381		$	350,456	$	(1,671,780	)	$	12,191,665
	Net margin	$	661,885		$	1,110,085		$	328,521	$	2,626		$	2,103,117
	Operating costs	257,658			296,402			111,037		4,560			669,657
	Depreciation and amortization	123,847			124,071			43,318		—			291,236
	Gain (loss) on sale of assets	219			(572		)	6,786		166			6,599
	Operating income	$	280,599		$	689,040		$	180,952	$	(1,768	)	$	1,148,823
	Equity earnings (loss) from investments	$	(56,141	)	$	27,326		$	69,818	$	—		$	41,003
	Investments in unconsolidated affiliates	$	254,818		$	490,582		$	387,253	$	—		$	1,132,653
	Total assets	$	4,727,201		$	8,082,692		$	1,823,917	$	737		$	14,634,547
	Noncontrolling interests in consolidated subsidiaries	$	4,251		$	163,671		$	—	$	15		$	167,937
	Capital expenditures	$	898,896		$	798,048		$	42,991	$	6,055		$	1,745,990
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $695.9 million, of which $598.1 million related to sales within the segment, net margin of $386.5 million and operating income of $196.1 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $290.0 million, net margin of $242.3 million and operating income of $106.5 million.
	Year Ended December 31, 2013	Natural Gas			Natural Gas			Natural Gas		Other and			Total
		Gathering and			Liquids (a)			Pipelines (b)		Eliminations
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	665,169		$	10,644,117		$	219,244	$	—		$	11,528,530
	Sales to affiliated customers	238,600			—			102,143		—			340,743
	Intersegment revenues	1,147,713			133,910			4,127		(1,285,750		)	—
	Total revenues	$	2,051,482		$	10,778,027		$	325,514	$	(1,285,750	)	$	11,869,273
	Net margin	$	500,627		$	869,938		$	285,719	$	(9,224	)	$	1,647,060
	Operating costs	193,293			236,638			101,182		(9,600		)	521,513
	Depreciation and amortization	103,962			89,240			43,541		—			236,743
	Gain (loss) on sale of assets	436			843			10,602		—			11,881
	Operating income	$	203,808		$	544,903		$	151,598	$	376		$	900,685
	Equity earnings from investments	$	23,493		$	21,978		$	65,046	$	—		$	110,517
	Investments in unconsolidated affiliates	$	333,179		$	491,856		$	404,803	$	—		$	1,229,838
	Total assets	$	3,949,813		$	6,938,633		$	1,817,675	$	156,487		$	12,862,608
	Noncontrolling interests in consolidated subsidiaries	$	4,521		$	—		$	—	$	15		$	4,536
	Capital expenditures	$	774,379		$	1,128,345		$	34,699	$	1,903		$	1,939,326
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $534.8 million, of which $449.9 million related to sales within the segment, net margin of $327.4 million and operating income of $190.5 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $246.9 million, net margin of $217.6 million and operating income of $90.5 million.
	Year Ended December 31, 2012	Natural Gas			Natural Gas			Natural Gas		Other and			Total
		Gathering and			Liquids (a)			Pipelines (b)		Eliminations
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	436,629		$	9,176,389		$	217,034	$	—		$	9,830,052
	Sales to affiliated customers	253,136			—			98,963		—			352,099
	Intersegment revenues	825,948			80,274			4,388		(910,610		)	—
	Total revenues	$	1,515,713		$	9,256,663		$	320,385	$	(910,610	)	$	10,182,151
	Net margin	$	455,170		$	907,340		$	286,060	$	(6,738	)	$	1,641,832
	Operating costs	164,033			223,844			101,899		(7,236		)	482,540
	Depreciation and amortization	83,031			74,344			45,726		—			203,101
	Loss on sale of assets	2,278			(932		)	5,390		—			6,736
	Operating income	$	210,384		$	608,220		$	143,825	$	498		$	962,927
	Equity earnings from investments	$	29,103		$	20,701		$	73,220	$	—		$	123,024
	Investments in unconsolidated affiliates	$	333,210		$	494,878		$	393,317	$	—		$	1,221,405
	Total assets	$	3,040,198		$	5,620,420		$	1,812,711	$	485,901		$	10,959,230
	Noncontrolling interests in consolidated subsidiaries	$	4,752		$	—		$	—	$	15		$	4,767
	Capital expenditures	$	566,126		$	968,549		$	25,383	$	455		$	1,560,513
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $470.6 million, of which $397.7 million related to sales within the segment, net margin of $276.3 million and operating income of $162.8 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $251.5 million, net margin of $220.3 million and operating income of $99.3 million.

QUARTERLY_FINANCIAL_DATA_UNAUD1

QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Data [Abstract]
Quarterly Financial Data
		First		Second		Third		Fourth
	Year Ended December 31, 2014	Quarter		Quarter		Quarter		Quarter
		(Thousands of dollars, except per unit amounts)
	Revenues	$	3,162,303	$	3,065,735	$	3,119,369	$	2,844,258
	Net margin	$	509,634	$	494,333	$	536,165	$	562,985
	Net income	$	265,468	$	214,511	$	167,320	$	264,036
	Net income attributable to ONEOK Partners, L.P.	$	265,392	$	214,434	$	167,247	$	263,225
	Limited partners’ per unit net income	$	0.81	$	0.54	$	0.32	$	0.67
		First		Second		Third		Fourth
	Year Ended December 31, 2013	Quarter		Quarter		Quarter		Quarter
		(Thousands of dollars, except per unit amounts)
	Revenues	$	2,517,447	$	2,768,179	$	3,134,733	$	3,448,914
	Net margin	$	370,599	$	411,953	$	423,574	$	440,934
	Net income	$	156,685	$	202,454	$	216,400	$	228,444
	Net income attributable to ONEOK Partners, L.P.	$	156,599	$	202,367	$	216,310	$	228,350
	Limited partners’ per unit net income	$	0.42	$	0.62	$	0.64	$	0.67

SUPPLEMENTAL_CONDENSED_CONSOLI1

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Statements of Income	Condensed Consolidating Statements of Income
		Year Ended December 31, 2014
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
		(Millions of dollars)
	Revenues
	Commodity sales	$	—		$	—			$	10,725.00		$	—		$	10,725.00
	Services	—			—				1,466.70			—			1,466.70
	Total revenues	—			—				12,191.70			—			12,191.70
	Cost of sales and fuel	—			—				10,088.60			—			10,088.60
	Net margin	—			—				2,103.10			—			2,103.10
	Operating expenses
	Operations and maintenance	—			—				599.1			—			599.1
	Depreciation and amortization	—			—				291.2			—			291.2
	General taxes	—			—				70.6			—			70.6
	Total operating expenses	—			—				960.9			—			960.9
	Gain (loss) on sale of assets	—			—				6.6			—			6.6
	Operating income	—			—				1,148.80			—			1,148.80
	Equity earnings (loss) from investments	910.3			910.3				(28.8		)	(1,750.8		)	41
	Allowance for equity funds used during construction	—			—				14.9			—			14.9
	Other income (expense), net	331.7			331.7				1.2			(663.4		)	1.2
	Interest expense	(331.7		)	(331.7		)		(281.9		)	663.4			(281.9		)
	Income before income taxes	910.3			910.3				854.2			(1,750.8		)	924
	Income taxes	—			—				(12.7		)	—			(12.7		)
	Net income	910.3			910.3				841.5			(1,750.8		)	911.3
	Less: Net income attributable to noncontrolling interests	—			—				1			—			1
	Net income attributable to ONEOK Partners, L.P.	$	910.3		$	910.3			$	840.5		$	(1,750.8	)	$	910.3
		Year Ended December 31, 2013
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
		(Millions of dollars)
	Revenues
	Commodity sales	$	—		$	—			$	10,549.20		$	—		$	10,549.20
	Services	—			—				1,320.10			—			1,320.10
	Total revenues	—			—				11,869.30			—			11,869.30
	Cost of sales and fuel	—			—				10,222.20			—			10,222.20
	Net margin	—			—				1,647.10			—			1,647.10
	Operating expenses
	Operations and maintenance	—			—				464.7			—			464.7
	Depreciation and amortization	—			—				236.7			—			236.7
	General taxes	—			—				56.9			—			56.9
	Total operating expenses	—			—				758.3			—			758.3
	Gain (loss) on sale of assets	—			—				11.9			—			11.9
	Operating income	—			—				900.7			—			900.7
	Equity earnings from investments	803.6			803.6				45.5			(1,542.2		)	110.5
	Allowance for equity funds used during construction	—			—				30.5			—			30.5
	Other income (expense), net	287.6			287.6				9.8			(575.2		)	9.8
	Interest expense	(287.6		)	(287.6		)		(236.7		)	575.2			(236.7		)
	Income before income taxes	803.6			803.6				749.8			(1,542.2		)	814.8
	Income taxes	—			—				(10.8		)	—			(10.8		)
	Net income	803.6			803.6				739			(1,542.2		)	804
	Less: Net income attributable to noncontrolling interests	—			—				0.4			—			0.4
	Net income attributable to ONEOK Partners, L.P.	$	803.6		$	803.6			$	738.6		$	(1,542.2	)	$	803.6
		Year Ended December 31, 2012
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
		(Millions of dollars)
	Revenues
	Commodity sales	$	—		$	—			$	9,010.20		$	—		$	9,010.20
	Services	—			—				1,172.00			—			1,172.00
	Total revenues	—			—				10,182.20			—			10,182.20
Cost of sales and fuel	—			—				8,540.40			—			8,540.40
Net margin	—			—				1,641.80			—			1,641.80
Operating expenses
Operations and maintenance	—			—				433			—			433
Depreciation and amortization	—			—				203.1			—			203.1
General taxes	—			—				49.5			—			49.5
Total operating expenses	—			—				685.6			—			685.6
Gain (loss) on sale of assets	—			—				6.7			—			6.7
Operating income	—			—				962.9			—			962.9
Equity earnings from investments	888			888				50.3			(1,703.3		)	123
Allowance for equity funds used during construction	—			—				13.6			—			13.6
Other income (expense), net	240.1			240.1				5			(480.2		)	5
Interest expense	(240.1		)	(240.1		)		(206.0		)	480.2			(206.0		)
Income before income taxes	888			888				825.8			(1,703.3		)	898.5
Income taxes	—			—				(10.1		)	—			(10.1		)
Net income	888			888				815.7			(1,703.3		)	888.4
Less: Net income attributable to noncontrolling interests	—			—				0.4			—			0.4
Net income attributable to ONEOK Partners, L.P.	$	888		$	888			$	815.3		$	(1,703.3	)	$	888
Condensed Consolidating Statements of Comprehensive Income	Condensed Consolidating Statements of Comprehensive Income
		Year Ended December 31, 2014
		Parent			Guarantor			Combined				Consolidating			Total
					Subsidiary			Non-Guarantor				Entries
								Subsidiaries
		(Millions of dollars)
	Net income	$	910.3		$	910.3			$	841.5		$	(1,750.8	)	$	911.3
	Other comprehensive income (loss)
	Unrealized gains (losses) on derivatives	(64.6		)	32.4				32.4			(64.8		)	(64.6		)
	Realized (gains) losses on derivatives recognized in net income	31.6			21.1				21.1			(42.2		)	31.6
	Total other comprehensive income (loss)	(33.0		)	53.5				53.5			(107.0		)	(33.0		)
	Comprehensive income	877.3			963.8				895			(1,857.8		)	878.3
	Less: Comprehensive income attributable to noncontrolling interests	—			—				1			—			1
	Comprehensive income attributable to ONEOK Partners, L.P.	$	877.3		$	963.8			$	894		$	(1,857.8	)	$	877.3
		Year Ended December 31, 2013
		Parent			Guarantor			Combined				Consolidating			Total
					Subsidiary			Non-Guarantor				Entries
								Subsidiaries
		(Millions of dollars)
	Net income	$	803.6		$	803.6			$	739		$	(1,542.2	)	$	804
	Other comprehensive income (loss)
	Unrealized gains (losses) on derivatives	32.1			(14.5		)		(14.5		)	29			32.1
	Realized (gains) losses on derivatives recognized in net income	8.4			(1.7		)		(1.7		)	3.4			8.4
	Total other comprehensive income (loss)	40.5			(16.2		)		(16.2		)	32.4			40.5
	Comprehensive income	844.1			787.4				722.8			(1,509.8		)	844.5
	Less: Comprehensive income attributable to noncontrolling interests	—			—				0.4			—			0.4
	Comprehensive income attributable to ONEOK Partners, L.P.	$	844.1		$	787.4			$	722.4		$	(1,509.8	)	$	844.1
		Year Ended December 31, 2012
		Parent			Guarantor			Combined				Consolidating			Total
					Subsidiary			Non-Guarantor				Entries
								Subsidiaries
		(Millions of dollars)
	Net income	$	888		$	888			$	815.7		$	(1,703.3	)	$	888.4
	Other comprehensive income (loss)
	Unrealized gains (losses) on derivatives	10.3			46.8				46.8			(93.6		)	10.3
	Realized (gains) losses on derivatives recognized in net income	(58.5		)	(61.5		)		(61.5		)	123			(58.5		)
	Total other comprehensive income (loss)	(48.2		)	(14.7		)		(14.7		)	29.4			(48.2		)
	Comprehensive income	839.8			873.3				801			(1,673.9		)	840.2
	Less: Comprehensive income attributable to noncontrolling interests	—			—				0.4			—			0.4
	Comprehensive income attributable to ONEOK Partners, L.P.	$	839.8		$	873.3			$	800.6		$	(1,673.9	)	$	839.8
Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheets
		December 31, 2014
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
	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				1,041.60			—			1,086.00
	Property, plant and equipment
	Property, plant and equipment	—			—				13,377.60			—			13,377.60
	Accumulated depreciation and amortization	—			—				1,842.10			—			1,842.10
	Net property, plant and equipment	—			—				11,535.50			—			11,535.50
	Investments and other assets
	Investments in unconsolidated affiliates	4,248.00			5,469.80				746.1			(9,331.3		)	1,132.60
	Intercompany notes receivable	8,843.30			7,579.00				—			(16,422.3		)	—
	Goodwill and intangible assets	—			—				822.4			—			822.4
	Other assets	36.2			—				21.8			—			58
	Total investments and other assets	13,127.50			13,048.80				1,590.30			(25,753.6		)	2,013.00
	Total assets	$	13,129.40		$	13,091.30			$	14,167.40		$	(25,753.6	)	$	14,634.50
	Liabilities and equity
	Current liabilities
	Current maturities of long-term debt	$	—		$	—			$	7.7		$	—		$	7.7
	Notes payable	1,055.30			—				—			—			1,055.30
	Accounts payable	—			—				874.7			—			874.7
	Affiliate payables	—			—				36.1			—			36.1
	Commodity imbalances	—			—				104.7			—			104.7
	Accrued interest	92			—				—			—			92
	Other current liabilities	44.8			—				120.8			—			165.6
	Total current liabilities	1,192.10			—				1,144.00			—			2,336.10
	Intercompany debt	—			8,843.30				7,579.00			(16,422.3		)	—
	Long-term debt, excluding current maturities	5,986.50			—				51.9			—			6,038.40
	Deferred credits and other liabilities	—			—				141.3			—			141.3
	Commitments and contingencies
	Equity
	Equity excluding noncontrolling interests in consolidated subsidiaries	5,950.80			4,248.00				5,083.30			(9,331.3		)	5,950.80
	Noncontrolling interests in consolidated subsidiaries	—			—				167.9			—			167.9
	Total equity	5,950.80			4,248.00				5,251.20			(9,331.3		)	6,118.70
	Total liabilities and equity	$	13,129.40		$	13,091.30			$	14,167.40		$	(25,753.6	)	$	14,634.50
		December 31, 2013
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
	Assets	(Millions of dollars)
	Current assets
	Cash and cash equivalents	$	—		$	134.5			$	—		$	—		$	134.5
	Accounts receivable, net	—			—				1,103.10			—			1,103.10
	Affiliate receivables	—			—				9.2			—			9.2
	Natural gas and natural gas liquids in storage	—			—				188.3			—			188.3
	Commodity imbalances	—			—				80.5			—			80.5
	Materials and supplies	—			—				54.1			—			54.1
	Other current assets	4.8			—				8.6			—			13.4
	Total current assets	4.8			134.5				1,443.80			—			1,583.10
	Property, plant and equipment
	Property, plant and equipment	—			—				10,755.00			—			10,755.00
	Accumulated depreciation and amortization	—			—				1,652.60			—			1,652.60
	Net property, plant and equipment	—			—				9,102.40			—			9,102.40
	Investments and other assets
Investments in unconsolidated affiliates	4,336.40			4,593.10				825.6			(8,525.3		)	1,229.80
Intercompany notes receivable	6,638.30			6,247.10				—			(12,885.4		)	—
Goodwill and intangible assets	—			—				832.2			—			832.2
Other assets	92.7			—				22.4			—			115.1
Total investments and other assets	11,067.40			10,840.20				1,680.20			(21,410.7		)	2,177.10
Total assets	$	11,072.20		$	10,974.70			$	12,226.40		$	(21,410.7	)	$	12,862.60
Liabilities and equity
Current liabilities
Current maturities of long-term debt	$	—		$	—			$	7.7		$	—		$	7.7
Notes payable	—			—				—			—			—
Accounts payable	—			—				1,255.40			—			1,255.40
Affiliate payables	—			—				47.5			—			47.5
Commodity imbalances	—			—				213.6			—			213.6
Accrued interest	92.7			—				—			—			92.7
Other current liabilities	—			—				89.1			—			89.1
Total current liabilities	92.7			—				1,613.30			—			1,706.00
Intercompany debt	—			6,638.30				6,247.10			(12,885.4		)	—
Long-term debt, excluding current maturities	5,985.30			—				59.6			—			6,044.90
Deferred credits and other liabilities	—			—				113			—			113
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consolidated subsidiaries	4,994.20			4,336.40				4,188.90			(8,525.3		)	4,994.20
Noncontrolling interests in consolidated subsidiaries	—			—				4.5			—			4.5
Total equity	4,994.20			4,336.40				4,193.40			(8,525.3		)	4,998.70
Total liabilities and equity	$	11,072.20		$	10,974.70			$	12,226.40		$	(21,410.7	)	$	12,862.60
Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statements of Cash Flows
		Year Ended December 31, 2014
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
		(Millions of dollars)
	Operating activities
	Cash provided by operating activities	$	1,155.70		$	69.8			$	1,136.50		$	(1,052.2	)	$	1,309.80
	Investing activities
	Capital expenditures (less allowance for equity funds used during construction)	—			—				(1,746.0		)	—			(1,746.0		)
	Cash paid for acquisitions, net of cash received	—			—				(814.9		)	—			(814.9		)
	Contributions to unconsolidated affiliates	—			—				(1.0		)	—			(1.0		)
	Distributions received from unconsolidated affiliates	—			17.7				3.4			—			21.1
	Proceeds from sale of assets	—			—				7.8			—			7.8
	Cash provided by (used in) investing activities	—			17.7				(2,550.7		)	—			(2,533.0		)
	Financing activities
	Cash distributions:
	General and limited partners	(1,052.2		)	(1,052.2		)		—			1,052.20			(1,052.2		)
	Noncontrolling interests	—			—				(0.6		)	—			(0.6		)
	Intercompany borrowings (advances), net	(2,295.2		)	872.7				1,422.50			—			—
	Borrowing (repayment) of notes payable, net	1,055.30			—				—			—			1,055.30
	Repayment of long-term debt	—			—				(7.7		)	—			(7.7		)
	Issuance of common units, net of issuance costs	1,113.10			—				—			—			1,113.10
	Contribution from general partner	23.3			—				—			—			23.3
	Cash provided by (used in) financing activities	(1,155.7		)	(179.5		)		1,414.20			1,052.20			1,131.20
	Change in cash and cash equivalents	—			(92.0		)		—			—			(92.0		)
	Cash and cash equivalents at beginning of period	—			134.5				—			—			134.5
	Cash and cash equivalents at end of period	$	—		$	42.5			$	—		$	—		$	42.5
		Year Ended December 31, 2013
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
		(Millions of dollars)
	Operating activities
	Cash provided by operating activities	$	870.7		$	65.1			$	981.6		$	(909.7	)	$	1,007.70
	Investing activities
	Capital expenditures (less allowance for equity funds used during construction)	—			(2.6		)		(1,936.7		)	—			(1,939.3		)
	Cash paid for acquisitions, net of cash received	—			—				(394.9		)	—			(394.9		)
	Contributions to unconsolidated affiliates	—			(30.8		)		(4.5		)	—			(35.3		)
	Distributions received from unconsolidated affiliates	—			19.4				11.7			—			31.1
	Proceeds from sale of assets	—			—				12.3			—			12.3
	Cash used in investing activities	—			(14.0		)		(2,312.1		)	—			(2,326.1		)
	Financing activities
	Cash distributions:
	General and limited partners	(909.7		)	(909.7		)		—			909.7			(909.7		)
	Noncontrolling interests	—			—				(0.6		)	—			(0.6		)
	Intercompany borrowings (advances), net	(1,794.8		)	456				1,338.80			—			—
	Issuance of long-term debt, net of discounts	1,247.80			—				—			—			1,247.80
	Long-term debt financing costs	(10.2		)	—				—			—			(10.2		)
	Repayment of long-term debt	—			—				(7.7		)	—			(7.7		)
	Issuance of common units, net of issuance costs	583.9			—				—			—			583.9
	Contribution from general partner	12.3			—				—			—			12.3
	Cash provided by (used in) financing activities	(870.7		)	(453.7		)		1,330.50			909.7			915.8
	Change in cash and cash equivalents	—			(402.6		)		—			—			(402.6		)
	Cash and cash equivalents at beginning of period	—			537.1				—			—			537.1
	Cash and cash equivalents at end of period	$	—		$	134.5			$	—		$	—		$	134.5
		Year Ended December 31, 2012
		Parent			Guarantor				Combined			Consolidating			Total
					Subsidiary				Non-Guarantor			Entries
									Subsidiaries
		(Millions of dollars)
	Operating activities
	Cash provided by operating activities	$	760.9		$	72.7			$	873.4		$	(760.9	)	$	946.1
	Investing activities
Capital expenditures (less allowance for equity funds used during construction)	—			—				(1,560.5		)	—			(1,560.5		)
Contributions to unconsolidated affiliates	—			—				(30.8		)	—			(30.8		)
Distributions received from unconsolidated affiliates	—			23				12.3			—			35.3
Proceeds from sale of assets	—			—				10.8			—			10.8
Cash provided by (used in) investing activities	—			23				(1,568.2		)	—			(1,545.2		)
Financing activities
Cash distributions:
General and limited partners	(760.9		)	(760.9		)		—			760.9			(760.9		)
Noncontrolling interests	—			—				(0.8		)	—			(0.8		)
Issuance of long-term debt, net of discounts	1,295.00			—				—			—			1,295.00
Long-term debt financing costs	(9.6		)	—				—			—			(9.6		)
Intercompany borrowings (advances), net	(1,873.9		)	1,167.20				706.7			—			—
Repayment of long-term debt	(350.0		)	—				(11.1		)	—			(361.1		)
Issuance of common units, net of issuance costs	919.4			—				—			—			919.4
Contribution from general partner	19.1			—				—			—			19.1
Cash provided by (used in) financing activities	(760.9		)	406.3				694.8			760.9			1,101.10
Change in cash and cash equivalents	—			502				—			—			502
Cash and cash equivalents at beginning of period	—			35.1				—			—			35.1
Cash and cash equivalents at end of period	$	—		$	537.1			$	—		$	—		$	537.1

SUMMARY_OF_SIGNIFICANT_ACCOUNT2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Y
Entity [Line Items]
Goodwill, Impairment Loss	$0	$0	$0
Investments in unconsolidated affiliates	1,132,653,000	1,229,838,000	1,221,405,000
Equity method goodwill	170,900,000	224,300,000
Impairment of Long-Lived Assets Held-for-use	0	0	0
General partnership ownership interest (in hundredths)	37.80%	41.20%
Limited partners ownership interest (in hundredths)	98.00%
Regulatory assets	6,100,000	6,800,000
Time period regulatory assets are being recovered (in years)	40
Northern Border Pipeline [Member]
Entity [Line Items]
Investments in unconsolidated affiliates	387,253,000	404,803,000
Net ownership percentage	50.00%
Bighorn Gas Gathering LLC [Member]
Entity [Line Items]
Investments in unconsolidated affiliates	$7,924,000	$87,837,000
Net ownership percentage	49.00%
General Partner [Member]
Entity [Line Items]
General partnership ownership interest (in hundredths)	2.00%

ACQUISITIONS_Details

ACQUISITIONS (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
		MMcf
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	$961,520
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest	800,934	304,889
West Texas LPG and Mesquite Systems [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Effective date of acquisition of business	30-Nov-14
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest	800,000
West Texas LPG Pipeline Limited Partnership [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	80.00%
Mesquite Pipeline [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	100.00%
Sage Creek Natural Gas Gathering And Processing [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Effective date of acquisition of business		30-Sep-13
Processing capacity of natural gas processing plant, per day		50
Sage Creek Natural Gas Gathering And Processing [Member] | Minimum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Useful life		20 years
Sage Creek Natural Gas Gathering And Processing [Member] | Maximum [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Useful life		30 years
Maysville Natural Gas Processing Facility [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Effective date of acquisition of business		1-Dec-13
Business Acquisition, Percentage of Voting Interests Acquired		30.00%
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest		90,000
Current ownership share in Maysville natural gas processing facility		100.00%
Natural Gas Gathering And Processing [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest		151,844
Natural Gas Liquids [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest		153,045
Pipelines [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		59,174
Pipelines [Member] | Natural Gas Gathering And Processing [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		41,129
Pipelines [Member] | Natural Gas Liquids [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		18,045

ACQUISITIONS_Schedule_of_purch

ACQUISITIONS Schedule of purchase price allocation (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	$13,839
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	961,520
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		103,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	987,860	212,889
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		92,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest	800,934	304,889
Goodwill	488,718	488,718
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	9,132
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other	3,369
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable	-8,621
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	-1,553
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	-10,174
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	-162,913
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	814,773
Business Combination, Cash Received	-13,839
Natural Gas Gathering And Processing [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		40,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		131,844
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		20,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest		151,844
Goodwill	112,141	112,141
Natural Gas Liquids [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		63,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		81,045
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		72,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest		153,045
Goodwill	247,566	247,566
Regulated Operation [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	807,601
Gathering pipelines and related equipment [member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		59,174
Gathering pipelines and related equipment [member] | Natural Gas Gathering And Processing [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		41,129
Gathering pipelines and related equipment [member] | Natural Gas Liquids [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		18,045
Processing and fractionation and related equipment [member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		50,595
Processing and fractionation and related equipment [member] | Natural Gas Gathering And Processing [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		50,595
Processing and fractionation and related equipment [member] | Natural Gas Liquids [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		0
Manufacturing Facility [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		120
Manufacturing Facility [Member] | Natural Gas Gathering And Processing [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		120
Manufacturing Facility [Member] | Natural Gas Liquids [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		0
Nonregulated Operation [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	$153,919

FAIR_VALUE_MEASUREMENTS_Part_1

FAIR VALUE MEASUREMENTS - Part 1 (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	$6,400,000,000	$6,500,000,000
Long-term Debt	6,000,000,000	6,100,000,000
Cash collateral held under master netting arrangements	24,800,000	0
Cash collateral posted under master netting arrangements	0	0
Fair Value, Measurements, Recurring [Member]
Derivative assets
Commodity contracts - financial	17,255,000	4,723,000
Commodity contracts - physical	9,922,000	1,077,000
Interest Rate Derivative Assets, at Fair Value	2,288,000	54,503,000
Total derivative assets	29,465,000	60,303,000
Derivative Liabilities
Commodity contracts - financial	0	-3,361,000
Commodity contracts - physical	-23,000	-2,517,000
Interest rate contracts	-44,843,000
Total derivative liabilities	-44,866,000	-5,878,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative assets
Commodity contracts - financial	42,880,000	0
Commodity contracts - physical	0	0
Interest Rate Derivative Assets, at Fair Value	0	0
Total derivative assets	42,880,000	0
Derivative Liabilities
Commodity contracts - financial	-169,000	0
Commodity contracts - physical	0	0
Interest rate contracts	0
Total derivative liabilities	-169,000	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative assets
Commodity contracts - financial	0	3,657,000
Commodity contracts - physical	0	0
Interest Rate Derivative Assets, at Fair Value	2,288,000	54,503,000
Total derivative assets	2,288,000	58,160,000
Derivative Liabilities
Commodity contracts - financial	0	-2,953,000
Commodity contracts - physical	0	0
Interest rate contracts	-44,843,000
Total derivative liabilities	-44,843,000	-2,953,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative assets
Commodity contracts - financial	354,000	2,812,000
Commodity contracts - physical	9,922,000	2,023,000
Interest Rate Derivative Assets, at Fair Value	0	0
Total derivative assets	10,276,000	4,835,000
Derivative Liabilities
Commodity contracts - financial	-968,000	-2,154,000
Commodity contracts - physical	-23,000	-3,463,000
Interest rate contracts	0
Total derivative liabilities	-991,000	-5,617,000
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivative assets
Commodity contracts - financial	43,234,000	6,469,000
Commodity contracts - physical	9,922,000	2,023,000
Interest Rate Derivative Assets, at Fair Value	2,288,000	54,503,000
Total derivative assets	55,444,000	62,995,000
Derivative Liabilities
Commodity contracts - financial	-1,137,000	-5,107,000
Commodity contracts - physical	-23,000	-3,463,000
Interest rate contracts	-44,843,000
Total derivative liabilities	-46,003,000	-8,570,000
Fair Value, Measurements, Recurring [Member] | Netting [Member]
Derivative assets
Commodity contracts - financial	-25,979,000	-1,746,000
Commodity contracts - physical	0	-946,000
Interest Rate Derivative Assets, at Fair Value	0	0
Total derivative assets	-25,979,000	-2,692,000
Derivative Liabilities
Commodity contracts - financial	1,137,000	1,746,000
Commodity contracts - physical	0	946,000
Interest rate contracts	0
Total derivative liabilities	$1,137,000	$2,692,000

FAIR_VALUE_MEASUREMENTS_Part_2

FAIR VALUE MEASUREMENTS - Part 2 (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Total realized/unrealized gains (losses): [Abstract]
Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets and liabilities still held as of the end of the period	$31	$959
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	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	-782	-2,423
Total realized/unrealized gains (losses): [Abstract]
Included in earnings	-927	959
Included in other comprehensive income (loss)	7,260	682
Purchases, issuances and settlements	3,734	0
Net assets (liabilities) at end of period	$9,285	($782)

RISK_MANAGEMENT_AND_HEDGING_AC2

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Part 1 (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Assets	$55,444,000	$62,995,000
(Liabilities)	-46,003,000	-8,570,000
Derivative, Net Liability Position, Aggregate Fair Value	0
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Assets	55,444,000	62,036,000
(Liabilities)	-45,980,000	-8,570,000
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Assets	2,288,000	54,503,000
(Liabilities)	-44,843,000	0
Designated as Hedging Instrument [Member] | Financial Derivative Instrument [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Assets	43,234,000	6,469,000
(Liabilities)	-1,137,000	-5,107,000
Designated as Hedging Instrument [Member] | Physical Derivative Instrument [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Assets	9,922,000	1,064,000
(Liabilities)	0	-3,463,000
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Assets	0	959,000
(Liabilities)	-23,000	0
Natural Gas Liquids [Member]
Derivatives, Fair Value [Line Items]
Derivative, Fair Value, Net	0	0
Natural Gas Pipelines [Member]
Derivatives, Fair Value [Line Items]
Derivative, Fair Value, Net	0	0
Physical Derivative Instrument [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Assets	0	959,000
(Liabilities)	($23,000)	$0

RISK_MANAGEMENT_AND_HEDGING_AC3

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Part 2 (Details) (Cash Flow Hedging [Member], USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Interest Rate Contract [Member] | Purchased [Member] | Forward Contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount	$900	$400
Notional Amount Of Cash Flow Hedge Instruments Greater Than 12 Months	400
Interest Rate Contract [Member] | Sold [Member] | Forward Contracts [Member]
Derivative [Line Items]
Derivative, Notional Amount	$0	$0
Crude oil and NGLs [Member] | Fixed Price [Member] | Purchased [Member] | Forwards and Swaps Contracts [Member]
Derivative [Line Items]
Notional amount	0	0
Crude oil and NGLs [Member] | Fixed Price [Member] | Sold [Member] | Forwards and Swaps Contracts [Member]
Derivative [Line Items]
Notional amount	-0.5	-4
Natural Gas [Member] | Fixed Price [Member] | Purchased [Member] | Swap [Member]
Derivative [Line Items]
Notional amount	0	0
Natural Gas [Member] | Fixed Price [Member] | Sold [Member] | Swap [Member]
Derivative [Line Items]
Notional amount	-41,200	-48,100
Natural Gas [Member] | Basis [Member] | Purchased [Member] | Swap [Member]
Derivative [Line Items]
Notional amount	0	0
Natural Gas [Member] | Basis [Member] | Sold [Member] | Swap [Member]
Derivative [Line Items]
Notional amount	-41,200	-48,100

RISK_MANAGEMENT_AND_HEDGING_AC4

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Part 3 (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Net unrealized loss in accumulated other comprehensive income (loss)	($91,823,000)	($58,837,000)	($99,322,000)
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	-64,639,000	32,141,000	10,295,000
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income (effective portion)	-31,653,000	-8,344,000	58,529,000
Gain (Loss) on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	0	0	0
Commodity Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income (effective portion)	21,052,000	-1,689,000
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	53,500,000
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income (effective portion)	10,601,000	10,033,000
Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	-10,800,000
Amount of accumulated other comprehensive income (loss) attributable primarily to settled interest-rate swaps.	-99,400,000
Interest Rate Contract [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income (effective portion)	-10,601,000	-10,033,000	-2,997,000
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	32,354,000	-14,475,000	46,804,000
Continuing Operations [Member] | Commodity Contract [Member] | Sales [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income (effective portion)	-21,052,000	1,689,000	61,526,000
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	($96,993,000)	$46,616,000	($36,509,000)

PROPERTY_PLANT_AND_EQUIPMENT_P

PROPERTY, PLANT AND EQUIPMENT - Part 1 (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Construction in Progress Expenditures Incurred but Not yet Paid	$187,200,000	$226,700,000	$216,500,000
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	13,377,617,000	10,755,048,000
Accumulated Depreciation	-1,842,084,000	-1,652,648,000
Property, plant and equipment, net	11,535,533,000	9,102,400,000
Non-Regulated Property, Plant and Equipment [Member]
Property, plant and equipment by type [Abstract]
Accumulated Depreciation	-1,123,261,000	-1,004,614,000
Non-Regulated Property, Plant and Equipment [Member] | Gathering pipelines and related equipment [member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	2,449,343,000	2,173,271,000
Non-Regulated Property, Plant and Equipment [Member] | Processing and fractionation and related equipment [member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	2,880,572,000	2,295,983,000
Non-Regulated Property, Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	478,276,000	362,704,000
Non-Regulated Property, Plant and Equipment [Member] | Transmission pipelines and related equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	518,585,000	302,718,000
Non-Regulated Property, Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	142,276,000	116,468,000
Non-Regulated Property, Plant and Equipment [Member] | Construction Work in Process [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	1,233,808,000	1,068,428,000
Regulated Property Plant and Equipment [Member]
Property, plant and equipment by type [Abstract]
Accumulated Depreciation	-718,823,000	-648,034,000
Regulated Property Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	115,799,000	135,922,000
Regulated Property Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	63,424,000	53,315,000
Regulated Property Plant and Equipment [Member] | Construction Work in Process [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	194,700,000	776,261,000
Regulated Property Plant and Equipment [Member] | Natural Gas Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	1,478,035,000	1,420,517,000
Regulated Property Plant and Equipment [Member] | Natural Gas Liquids Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment, gross	$3,822,799,000	$2,049,461,000
Minimum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Gathering pipelines and related equipment [member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Minimum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Processing and fractionation and related equipment [member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	3 years
Minimum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Minimum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Transmission pipelines and related equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Minimum [Member] | Non-Regulated Property, Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	2 years
Minimum [Member] | Regulated Property Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Minimum [Member] | Regulated Property Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	2 years
Minimum [Member] | Regulated Property Plant and Equipment [Member] | Natural Gas Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Minimum [Member] | Regulated Property Plant and Equipment [Member] | Natural Gas Liquids Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Maximum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Gathering pipelines and related equipment [member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	40 years
Maximum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Processing and fractionation and related equipment [member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	40 years
Maximum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	54 years
Maximum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Transmission pipelines and related equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	54 years
Maximum [Member] | Non-Regulated Property, Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	60 years
Maximum [Member] | Regulated Property Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	54 years
Maximum [Member] | Regulated Property Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	53 years
Maximum [Member] | Regulated Property Plant and Equipment [Member] | Natural Gas Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	77 years
Maximum [Member] | Regulated Property Plant and Equipment [Member] | Natural Gas Liquids Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	80 years

PROPERTY_PLANT_AND_EQUIPMENT_P1

PROPERTY, PLANT AND EQUIPMENT - Part 2 (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Construction Work in Process Incurred but Not yet Paid	$187.20	$226.70	$216.50
Regulated Property Plant and Equipment [Member] | Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Average Depreciation Rate	2.00%	2.00%	1.90%
Regulated Property Plant and Equipment [Member] | Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Average Depreciation Rate	2.10%	2.20%	2.20%

GOODWILL_AND_INTANGIBLE_ASSETS2

GOODWILL AND INTANGIBLE ASSETS (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Goodwill	$488,718,000	$488,718,000
Amortization expense for intangible assets	11,800,000	8,700,000	7,700,000
Future amortization expense for next five years [Abstract]
Future amortization expense, year one	11,800,000
Future amortization expense, year two	11,800,000
Future amortization expense, year three	11,800,000
Future amortization expense, year four	11,800,000
Future amortization expense, year five	11,800,000
Gross intangible assets and accumulated amortization [Abstract]
Gross intangible assets	411,650,000	409,650,000
Accumulated amortization	-78,010,000	-66,188,000
Net intangible assets	333,640,000	343,462,000
Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Goodwill	112,141,000	112,141,000
Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Goodwill	129,011,000	129,011,000
Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Goodwill	247,566,000	247,566,000
Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Goodwill, Acquired During Period	20,000,000
Finite-Lived Intangible Asset, Useful Life	20 years
Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Goodwill, Acquired During Period	$72,000,000
Finite-Lived Intangible Asset, Useful Life	40 years

CREDIT_FACILITIES_AND_SHORTTER1

CREDIT FACILITIES AND SHORT-TERM NOTES PAYABLE (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Jan. 31, 2014	Mar. 31, 2014
Line of Credit Facility [Line Items]
Total short-term borrowings authorized by our general partner's Board of Directors	$2,500,000,000
Partnership 2014 Credit Agreement [Member]
Line of Credit Facility [Line Items]
Swingline subfacility		150,000,000
Option to increase borrowing capacity	2,400,000,000
Partnership Credit Agreement [Member]
Line of Credit Facility [Line Items]
Commercial paper outstanding	1,100,000,000
Letters of credit issued	14,000,000
Borrowings outstanding under our Partnership Credit Agreement	0
Maximum Amount Of Commercial Paper	1,700,000,000		1,200,000,000
Sublimit for issuance of standby letters of credit	100,000,000
Option to increase borrowing capacity	2,400,000,000
Indebtedness To Adjusted Ebitda Maximum	5
Acquisition price threshold for increase in permitted debt to EBITDA covenant ratio	$25,000,000
Indebtedness To Adjusted Ebitda From Acquisitions Maximum	5.5
Indebtedness To Adjusted Ebitda Current	3.7
Interest rate description	borrowings, if any, will accrue at LIBOR plus 117.5 basis points
Line Of Credit Facility, Annual Facility Fee Description	the annual facility fee is 20 basis points

LONGTERM_DEBT_Details

LONG-TERM DEBT (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Long-term Debt, Gross	$6,059,557,000	$6,067,208,000
2014	7,700,000
2015	1,107,700,000
2016	407,700,000
2017	432,700,000
2018	507,700,000
Unamortized debt discount and other	-13,528,000	-14,691,000
Current maturities	-7,650,000	-7,650,000
Long-term debt, excluding current maturities	6,038,379,000	6,044,867,000
ONEOK Partners [Member]
Debt Instrument [Line Items]
2014	0
2015	1,100,000,000
2016	400,000,000
2017	425,000,000
2018	500,000,000
ONEOK Partners [Member] | Note Payable from Public Offering Due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	650,000,000	650,000,000
Interest rates (in hundredths)	3.25%
ONEOK Partners [Member] | Notes Payable due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	450,000,000	450,000,000
Interest rates (in hundredths)	6.15%
ONEOK Partners [Member] | Note Payable from Public Offering Due 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			400,000,000
Long-term Debt, Gross	400,000,000	400,000,000
Interest rates (in hundredths)	2.00%		2.00%
ONEOK Partners [Member] | Note Payable from Public Offering Due 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		425,000,000
Long-term Debt, Gross	425,000,000	425,000,000
Interest rates (in hundredths)	3.20%	3.20%
ONEOK Partners [Member] | Notes Payables due 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	500,000,000	500,000,000
Interest rates (in hundredths)	8.63%
ONEOK Partners [Member] | Note Payable from Public Offering Due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			900,000,000
Long-term Debt, Gross	900,000,000	900,000,000
Interest rates (in hundredths)	3.38%		3.38%
ONEOK Partners [Member] | Note Payable from Public Offering Due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		425,000,000
Long-term Debt, Gross	425,000,000	425,000,000
Interest rates (in hundredths)	5.00%	5.00%
ONEOK Partners [Member] | Notes Payables due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	600,000,000	600,000,000
Interest rates (in hundredths)	6.65%
ONEOK Partners [Member] | Notes Payables due 2037 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	600,000,000	600,000,000
Interest rates (in hundredths)	6.85%
ONEOK Partners [Member] | Note Payable from Public Offering Due 2041 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	650,000,000	650,000,000
Interest rates (in hundredths)	6.13%
ONEOK Partners [Member] | Note Payable from Public Offering Due 2043 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		400,000,000
Long-term Debt, Gross	400,000,000	400,000,000
Interest rates (in hundredths)	6.20%	6.20%
ONEOK Partners [Member] | Notes Payables due 2012 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount			350,000,000
Interest rates (in hundredths)			5.90%
Guardian Pipeline [Member] | Notes Payables due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	59,557,000	67,208,000
2014	7,700,000
2015	7,700,000
2016	7,700,000
2017	7,700,000
2018	7,700,000
Debt instrument covenant description	Guardian Pipelinebs senior notes contain financial covenants that require the maintenance of certain financial ratios as defined in the master shelf agreement based on Guardian Pipelinebs financial position and results of operations.B B Upon any breach of these covenants, all amounts outstanding under the master shelf agreement may become due and payable immediately.
Year of maturity	30-Sep-22
Average interest rate (in hundredths)	7.85%
Debt Instrument, Covenant Compliance	At December 31, 2014, Guardian Pipeline was in compliance with its financial covenants.
Master shelf agreement initiation date	8-Nov-01
Senior Notes [Member] | ONEOK Partners [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		1,250,000,000	1,300,000,000
Debt instrument call feature	We may redeem our senior notes due 2016 (6.15 percent), 2019, 2036 and 2037, in whole or in part, at any time prior to their maturity 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. We may redeem our senior notes due 2017 and our senior notes due 2022 at par starting one month and three months, respectively, before their maturity dates. We may redeem our senior notes due 2016 (3.25 percent) and 2041 at a redemption price equal to the principal amount, plus accrued and unpaid interest, starting one month and six 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. We may redeem our senior notes due 2018, 2023 and 2043 at par, plus accrued and unpaid interest to the redemption date, starting one month, three months, and six 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.
Debt instrument covenant description	Our senior notes are governed by an indenture, dated as of September 25, 2006, between us and Wells Fargo Bank, N.A., the trustee, as supplemented.B B 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.B B 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.B B The indenture includes an event of default upon acceleration of other indebtedness of $100 million or more.B B 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.
Net proceeds from the public offering		$1,240,000,000	$1,290,000,000

EQUITY_Details

EQUITY (Details) (USD $)	3 Months Ended													12 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Equity [Abstract]
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.B B Our general partnerbs percentage interest in quarterly distributions is increased after certain specified target levels are met during the quarter.B B 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.
Partnership Capital Distributions [Line Items]
General partnership ownership interest (in hundredths)														37.80%	41.20%
Rights to receive increased quarterly distribution on Class B Units														Our Class B limited partner units are entitled to receive increased quarterly distributions equal to 110 percent of the distributions paid with respect to our common units.
Number of days notice of withdrawal of waiver (in days)	90													90
Number of common units owned by related party	19.8													19.8
Aggregate dollar amount of common units available for issuance and sale under the Equity Distribution Agreement.														$650,000,000
Aggregate Amount of Equity Distribution Agreement Utilized														300,000,000
Line of Credit Facility, Remaining Borrowing Capacity	514,000,000													514,000,000
Contribution from general partner														23,155,000	12,366,000	19,069,000
Total distributions														1,052,794,000	910,301,000	761,695,000
Percentage of increase in quarterly distributions entitled to Class B limited partners units														123.50%
Percentage of increase in quarterly distribution payable on Class B limited partner units upon removal of general partner														123.50%
General Partner [Member]
Partnership Capital Distributions [Line Items]
General partnership ownership interest (in hundredths)														2.00%
Dividend Paid [Member]
Partnership Capital Distributions [Line Items]
Distributions Per Limited Partnership and General Partnership Unit, Outstanding, Basic														$3.01	$2.87	$2.59
Total distributions														1,052,245,000	909,713,000	760,912,000
Dividend Paid [Member] | General Partner [Member]
Partnership Capital Distributions [Line Items]
General partner distributions														21,044,000	18,193,000	15,217,000
Incentive distribution														304,999,000	251,664,000	186,130,000
Distributions to general partner														326,043,000	269,857,000	201,347,000
Dividend Paid [Member] | Limited Partner [Member]
Partnership Capital Distributions [Line Items]
Limited partner distributions to ONEOK														279,292,000	266,302,000	235,442,000
Limited partner distributions to other unitholders														446,910,000	373,554,000	324,123,000
Dividend Declared [Member]
Partnership Capital Distributions [Line Items]
Distributions Per Limited Partnership and General Partnership Unit, Outstanding, Basic	$0.79	$0.78	$0.76	$0.75	$0.73	$0.73	$0.72	$0.72	$0.71	$0.69	$0.66	$0.64	$0.61	$3.07	$2.89	$2.69
Total distributions														1,105,457,000	931,236,000	817,754,000
Dividend Declared [Member] | General Partner [Member]
Partnership Capital Distributions [Line Items]
General partner distributions														22,109,000	18,625,000	16,355,000
Incentive distribution														326,022,000	259,466,000	210,095,000
Distributions to general partner														348,131,000	278,091,000	226,450,000
Dividend Declared [Member] | Limited Partner [Member]
Partnership Capital Distributions [Line Items]
Limited partner distributions to ONEOK														284,860,000	268,157,000	249,600,000
Limited partner distributions to other unitholders														472,466,000	384,988,000	341,704,000
ONEOK Partners [Member] | Notes Payables due 2012 [Member]
Partnership Capital Distributions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage									5.90%							5.90%
Issued under public offering [Member]
Partnership Capital Distributions [Line Items]
Partners' Capital Account, Units, Sold in Public Offering														13.9	11.5	8
Public offering price of common units														$52.94	$49.61	$59.27
Proceeds from Sale of Interest in Partnership Unit														714,500,000	553,400,000	460,000,000
Contribution from general partner														15,000,000	11,600,000	19,000,000
Issued under private placement [Member]
Partnership Capital Distributions [Line Items]
Number of common units to related party in a private placement (in number of units)																8
Proceeds from Issuance of Private Placement																460,000,000
Issued Under Equity Distribution Agreement [Member]
Partnership Capital Distributions [Line Items]
Partners' Capital Account, Units, Sold Under Equity Distribution Agreement														7.9	0.7
Proceeds from Sale of Interest in Partnership Unit														$402,100,000	$36,100,000

ACCUMULATED_OTHER_COMPREHENSIV2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated other comprehensive loss - January 1	($58,837)	($99,322)
Amounts reclassified from accumulated other comprehensive income (loss)	31,653	8,344	-58,529
Net current-period other comprehensive income (loss) attributable to ONEOK Partners, L.P.	-32,986	40,485	-48,234
Accumulated other comprehensive loss - December 31	-91,823	-58,837	-99,322
Commodity Contract [Member]
Unrealized (gains) losses on risk-management assets/liabilities	21,052	-1,689
Interest Rate Contract [Member]
Unrealized (gains) losses on risk-management assets/liabilities	10,601	10,033
Cash Flow Hedging [Member]
Other comprehensive income (loss) before reclassifications	-64,639	32,141	10,295
Unrealized (gains) losses on risk-management assets/liabilities	($31,653)	($8,344)	$58,529

LIMITED_PARTNERS_NET_INCOME_PE1

LIMITED PARTNERS' NET INCOME PER UNIT (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
LIMITED PARTNERS' NET INCOME PER UNIT (Details) [Abstract]
General partnership ownership interest (in hundredths)	37.80%	41.20%
Number of days notice of withdrawal of waiver (in days)	90
General Partner [Member]
LIMITED PARTNERS' NET INCOME PER UNIT (Details) [Abstract]
General partnership ownership interest (in hundredths)	2.00%
Dividend Declared [Member] | General Partner [Member]
LIMITED PARTNERS' NET INCOME PER UNIT (Details) [Abstract]
Incentive distribution allocated to general partner	$326,022	$259,466	$210,095

INCOME_TAXES_Details

INCOME TAXES (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Federal	$59	$56	($156)
State	1,777	5,358	3,446
Total current income tax provision	1,836	5,414	3,290
Deferred income tax provision
Federal	5,033	4,303	6,330
State	5,799	1,141	485
Total deferred income tax provision	10,832	5,444	6,815
Income before income taxes	924,003	814,841	898,533
Less: Net income attributable to noncontrolling interests	1,037	357	438
Income attributable to ONEOK Partners, L.P. before income taxes	922,966	814,484	898,095
Federal statutory income tax rate	35.00%	35.00%	35.00%
Provision for federal income taxes	323,038	285,069	314,333
Partnership earnings not subject to tax	-318,021	-280,992	-307,839
State income taxes, net of federal benefit	7,576	6,095	4,530
Other, net	75	686	-919
Income tax provision	12,668	10,858	10,105
Deferred tax assets
Federal and state net operating loss	3,179	1,410
Other	1,626	1,521
Total deferred tax assets	4,805	2,931
Deferred tax liabilities
Excess of tax over book depreciation	61,120	48,433
Regulatory assets	1,962	1,978
Total deferred tax liabilities	63,082	50,411
Net deferred tax liabilities	$58,277	$47,480

UNCONSOLIDATED_AFFILIATES_Deta

UNCONSOLIDATED AFFILIATES (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Equity earnings from investments	$41,003,000	$110,517,000	$123,024,000
Income (loss) from equity method investments before impairments	94,424,000	110,517,000	123,024,000
Investments in unconsolidated affiliates	1,132,653,000	1,229,838,000	1,221,405,000
Equity method goodwill	170,900,000	224,300,000
Accounts Payable, Related Parties, Current	20,500,000	6,900,000
Payments to Acquire Other Investments	1,063,000	35,308,000	30,768,000
Balance Sheet [Abstract]
Current assets	153,293,000	155,310,000
Property, plant and equipment, net	2,440,714,000	2,557,571,000
Other noncurrent assets	35,668,000	34,478,000
Current liabilities	95,026,000	98,967,000
Long-term debt	428,385,000	442,103,000
Other noncurrent liabilities	73,767,000	58,221,000
Accumulated other comprehensive loss	-2,063,000	-2,291,000
Owners' equity	2,034,560,000	2,150,359,000
Income Statement [Abstract]
Operating revenues	548,491,000	528,665,000	573,197,000
Operating expenses	309,990,000	256,292,000	269,858,000
Net income	214,410,000	248,998,000	279,766,000
Distributions paid to us	139,019,000	137,498,000	155,741,000
Unconsolidated Affiliates [Member]
Schedule of Equity Method Investments [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	62,000,000	53,800,000	36,100,000
Overland Pass Pipeline Company [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings from investments	25,906,000	20,461,000	20,043,000
Investments in unconsolidated affiliates	466,977,000	466,671,000
Net ownership percentage	50.00%
Northern Border Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings from investments	69,819,000	65,046,000	72,705,000
Investments in unconsolidated affiliates	387,253,000	404,803,000
Net ownership percentage	50.00%
Payments to Acquire Other Investments		30,800,000
Percentage decrease in long-term transportation rates		11.00%
Fort Union Gas Gathering LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings from investments	16,619,000	15,826,000	17,218,000
Investments in unconsolidated affiliates	127,876,000	125,220,000
Net ownership percentage	37.00%
Bighorn Gas Gathering LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Other than Temporary Impairment	53,421,000	0	0
Equity Method Investments, Proportionate Share of Investee Impairment of Long-Lived Assets Charge	23,000,000
Equity earnings from investments	-25,621,000	1,952,000	3,820,000
Investments in unconsolidated affiliates	7,924,000	87,837,000
Net ownership percentage	49.00%
Equity Method Investment, Other than Temporary Impairment	76,400,000
Other Unconsolidated Affiliate [Member]
Schedule of Equity Method Investments [Line Items]
Equity earnings from investments	7,701,000	7,232,000	9,238,000
Investments in unconsolidated affiliates	142,623,000	145,307,000
Powder River Basin Other Than Bighorn Gas Gathering [Member]
Schedule of Equity Method Investments [Line Items]
Equity method goodwill	130,500,000
Equity Method Investment, Underlying Equity in Net Assets	$206,000,000

RELATEDPARTY_TRANSACTIONS_Deta

RELATED-PARTY TRANSACTIONS (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transactions [Abstract]
General partnership ownership interest (in hundredths)	37.80%	41.20%
Related Party Transaction [Line Items]
Contribution from general partner	$23,155	$12,366	$19,069
General Partner [Member]
Related Party Transactions [Abstract]
General partnership ownership interest (in hundredths)	2.00%
ONEOK [Member]
Transactions With Related Parties [Abstract]
Revenues		340,743	352,099
Expenses [Abstract]
Cost of sales and fuel		37,963	33,094
Administrative and general expenses		265,448	246,050
Total expenses	341,376	303,411	279,144
General Partner [Member]
Related Party Transaction [Line Items]
Contribution from general partner	23,155	12,366	19,069
ONEOK [Member]
Transactions With Related Parties [Abstract]
Revenues	53,526
Expenses [Abstract]
Cost of sales and fuel	10,835
Administrative and general expenses	$330,541

COMMITMENTS_AND_CONTINGENCIES_1

COMMITMENTS AND CONTINGENCIES (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Operating Leased Assets [Line Items]
PercentageYieldOfHighConsequencePipelineAreas	30.00%
Firm Transportation and Storage Contracts [Abstract]
Total	$222.80
Oneok Partners [Member]
Firm Transportation and Storage Contracts [Abstract]
2015	33.6
2016	32.1
2017	30.4
2018	29.4
2019	28.8
Thereafter	$68.50

SEGMENTS_Details

SEGMENTS (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Segment Reporting, Disclosure of Major Customers									we had no single customer from which we received 10 percent or more of our consolidated revenues.	we had no single customer from which we received 10 percent or more of our consolidated revenues.	we had no single customer from which we received 10 percent or more of our consolidated revenues.
Revenues	$2,844,258	$3,119,369	$3,065,735	$3,162,303	$3,448,914	$3,134,733	$2,768,179	$2,517,447	$12,191,665	$11,869,273	$10,182,151
Net margin	562,985	536,165	494,333	509,634	440,934	423,574	411,953	370,599	2,103,117	1,647,060	1,641,832
Operating costs									669,657	521,513	482,540
Depreciation and amortization									291,236	236,743	203,101
Gain (loss) on sale of assets									6,599	11,881	6,736
Operating income									1,148,823	900,685	962,927
Equity earnings from investments									41,003	110,517	123,024
Investments in unconsolidated affiliates	1,132,653				1,229,838				1,132,653	1,229,838	1,221,405
Total assets	14,634,547				12,862,608				14,634,547	12,862,608	10,959,230
Noncontrolling interests in consolidated subsidiaries	167,937				4,536				167,937	4,536	4,767
Capital expenditures									1,745,990	1,939,326	1,560,513
Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Revenues									350,456	325,514	320,385
Net margin									328,521	285,719	286,060
Operating costs									111,037	101,182	101,899
Depreciation and amortization									43,318	43,541	45,726
Gain (loss) on sale of assets									6,786	10,602	5,390
Operating income									180,952	151,598	143,825
Equity earnings from investments									69,818	65,046	73,220
Investments in unconsolidated affiliates	387,253				404,803				387,253	404,803	393,317
Total assets	1,823,917				1,817,675				1,823,917	1,817,675	1,812,711
Noncontrolling interests in consolidated subsidiaries	0				0				0	0	0
Capital expenditures									42,991	34,699	25,383
Natural Gas Pipelines [Member] | Natural Gas Pipelines Regulated [Member]
Segment Reporting Information [Line Items]
Revenues									290,000	246,900	251,500
Net margin									242,300	217,600	220,300
Operating income									106,500	90,500	99,300
Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Revenues									10,545,381	10,778,027	9,256,663
Net margin									1,110,085	869,938	907,340
Operating costs									296,402	236,638	223,844
Depreciation and amortization									124,071	89,240	74,344
Gain (loss) on sale of assets									-572	843	-932
Operating income									689,040	544,903	608,220
Equity earnings from investments									27,326	21,978	20,701
Investments in unconsolidated affiliates	490,582				491,856				490,582	491,856	494,878
Total assets	8,082,692				6,938,633				8,082,692	6,938,633	5,620,420
Noncontrolling interests in consolidated subsidiaries	163,671				0				163,671	0	0
Capital expenditures									798,048	1,128,345	968,549
Natural Gas Liquids [Member] | Natural Gas Liquids Regulated [Member]
Segment Reporting Information [Line Items]
Revenues									695,900	534,800	470,600
Net margin									386,500	327,400	276,300
Operating income									196,100	190,500	162,800
Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenues									2,967,608	2,051,482	1,515,713
Net margin									661,885	500,627	455,170
Operating costs									257,658	193,293	164,033
Depreciation and amortization									123,847	103,962	83,031
Gain (loss) on sale of assets									219	436	2,278
Operating income									280,599	203,808	210,384
Equity earnings from investments									-56,141	23,493	29,103
Investments in unconsolidated affiliates	254,818				333,179				254,818	333,179	333,210
Total assets	4,727,201				3,949,813				4,727,201	3,949,813	3,040,198
Noncontrolling interests in consolidated subsidiaries	4,251				4,521				4,251	4,521	4,752
Capital expenditures									898,896	774,379	566,126
Other and Eliminations
Segment Reporting Information [Line Items]
Revenues									-1,671,780	-1,285,750	-910,610
Net margin									2,626	-9,224	-6,738
Operating costs									4,560	-9,600	-7,236
Depreciation and amortization									0	0	0
Gain (loss) on sale of assets									166	0	0
Operating income									-1,768	376	498
Equity earnings from investments									0	0	0
Investments in unconsolidated affiliates	0				0				0	0	0
Total assets	737				156,487				737	156,487	485,901
Noncontrolling interests in consolidated subsidiaries	15				15				15	15	15
Capital expenditures									6,055	1,903	455
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues									0	0	0
Operating Segments [Member] | Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Revenues									8,343	4,127	4,388
Operating Segments [Member] | Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Revenues									215,772	133,910	80,274
Operating Segments [Member] | Natural Gas Liquids [Member] | Natural Gas Liquids Regulated [Member]
Segment Reporting Information [Line Items]
Revenues									598,100	449,900	397,700
Operating Segments [Member] | Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenues									1,447,665	1,147,713	825,948
Operating Segments [Member] | Other and Eliminations
Segment Reporting Information [Line Items]
Revenues									-1,671,780	-1,285,750	-910,610
Affiliated Entity [Member]
Segment Reporting Information [Line Items]
Revenues									53,526	340,743	352,099
Affiliated Entity [Member] | Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Revenues									12,312	102,143	98,963
Affiliated Entity [Member] | Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Revenues									0	0	0
Affiliated Entity [Member] | Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenues									41,214	238,600	253,136
Affiliated Entity [Member] | Other and Eliminations
Segment Reporting Information [Line Items]
Revenues									0	0	0
Unaffiliated entity [Member]
Segment Reporting Information [Line Items]
Revenues									12,138,139	11,528,530	9,830,052
Unaffiliated entity [Member] | Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Revenues									329,801	219,244	217,034
Unaffiliated entity [Member] | Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Revenues									10,329,609	10,644,117	9,176,389
Unaffiliated entity [Member] | Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenues									1,478,729	665,169	436,629
Unaffiliated entity [Member] | Other and Eliminations
Segment Reporting Information [Line Items]
Revenues									$0	$0	$0

QUARTERLY_FINANCIAL_DATA_UNAUD2

QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Data [Abstract]
Revenues	$2,844,258	$3,119,369	$3,065,735	$3,162,303	$3,448,914	$3,134,733	$2,768,179	$2,517,447	$12,191,665	$11,869,273	$10,182,151
Net margin	562,985	536,165	494,333	509,634	440,934	423,574	411,953	370,599	2,103,117	1,647,060	1,641,832
Net income	264,036	167,320	214,511	265,468	228,444	216,400	202,454	156,685	911,335	803,983	888,428
Net income attributable to ONEOK Partners, L.P.	$263,225	$167,247	$214,434	$265,392	$228,350	$216,310	$202,367	$156,599	$910,298	$803,626	$887,990
Limited partners' per unit net income	$0.67	$0.32	$0.54	$0.81	$0.67	$0.64	$0.62	$0.42	$2.33	$2.35	$3.04

SUPPLEMENTAL_CONDENSED_CONSOLI2

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION CONDENSED CONSOLIDATING FINANCIAL STATEMENTS, Income Statement (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Commodity Sales									$10,724,981,000	$10,549,157,000	$9,010,151,000
Services									1,466,684,000	1,320,116,000	1,172,000,000
Total revenues	2,844,258,000	3,119,369,000	3,065,735,000	3,162,303,000	3,448,914,000	3,134,733,000	2,768,179,000	2,517,447,000	12,191,665,000	11,869,273,000	10,182,151,000
Cost of sales and fuel									10,088,548,000	10,222,213,000	8,540,319,000
Net margin	562,985,000	536,165,000	494,333,000	509,634,000	440,934,000	423,574,000	411,953,000	370,599,000	2,103,117,000	1,647,060,000	1,641,832,000
Operating Expenses
Operations and maintenance									599,076,000	464,633,000	433,063,000
Depreciation and amortization									291,236,000	236,743,000	203,101,000
General taxes									70,581,000	56,880,000	49,477,000
Total operating expenses									960,893,000	758,256,000	685,641,000
Gain (loss) on sale of assets									6,599,000	11,881,000	6,736,000
Operating income									1,148,823,000	900,685,000	962,927,000
Equity earnings from investments									41,003,000	110,517,000	123,024,000
Allowance for equity funds used during construction									14,937,000	30,522,000	13,648,000
Interest expense									-281,908,000	-236,714,000	-206,018,000
Income before income taxes									924,003,000	814,841,000	898,533,000
Income taxes									-12,668,000	-10,858,000	-10,105,000
Net income	264,036,000	167,320,000	214,511,000	265,468,000	228,444,000	216,400,000	202,454,000	156,685,000	911,335,000	803,983,000	888,428,000
Less: Net income attributable to noncontrolling interests									1,037,000	357,000	438,000
Net income attributable to ONEOK Partners, L.P.	263,225,000	167,247,000	214,434,000	265,392,000	228,350,000	216,310,000	202,367,000	156,599,000	910,298,000	803,626,000	887,990,000
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Commodity Sales									0	0	0
Services									0	0	0
Total revenues									0	0	0
Cost of sales and fuel									0	0	0
Net margin									0	0	0
Operating Expenses
Operations and maintenance									0	0	0
Depreciation and amortization									0	0	0
General taxes									0	0	0
Total operating expenses									0	0	0
Gain (loss) on sale of assets									0	0	0
Operating income									0	0	0
Equity earnings from investments									910,300,000	803,600,000	888,000,000
Allowance for equity funds used during construction									0	0	0
Other income (expense), net									331,700,000	287,600,000	240,100,000
Interest expense									-331,700,000	-287,600,000	-240,100,000
Income before income taxes									910,300,000	803,600,000	888,000,000
Income taxes									0	0	0
Net income									910,300,000	803,600,000	888,000,000
Less: Net income attributable to noncontrolling interests									0	0	0
Net income attributable to ONEOK Partners, L.P.									910,300,000	803,600,000	888,000,000
Guarantor Subsidiary [Member]
Condensed Financial Statements, Captions [Line Items]
Commodity Sales									0	0	0
Services									0	0	0
Total revenues									0	0	0
Cost of sales and fuel									0	0	0
Net margin									0	0	0
Operating Expenses
Operations and maintenance									0	0	0
Depreciation and amortization									0	0	0
General taxes									0	0	0
Total operating expenses									0	0	0
Gain (loss) on sale of assets									0	0	0
Operating income									0	0	0
Equity earnings from investments									910,300,000	803,600,000	888,000,000
Allowance for equity funds used during construction									0	0	0
Other income (expense), net									331,700,000	287,600,000	240,100,000
Interest expense									-331,700,000	-287,600,000	-240,100,000
Income before income taxes									910,300,000	803,600,000	888,000,000
Income taxes									0	0	0
Net income									910,300,000	803,600,000	888,000,000
Less: Net income attributable to noncontrolling interests									0	0	0
Net income attributable to ONEOK Partners, L.P.									910,300,000	803,600,000	888,000,000
Combined Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Commodity Sales									10,725,000,000	10,549,200,000	9,010,200,000
Services									1,466,700,000	1,320,100,000	1,172,000,000
Total revenues									12,191,700,000	11,869,300,000	10,182,200,000
Cost of sales and fuel									10,088,600,000	10,222,200,000	8,540,400,000
Net margin									2,103,100,000	1,647,100,000	1,641,800,000
Operating Expenses
Operations and maintenance									599,100,000	464,700,000	433,000,000
Depreciation and amortization									291,200,000	236,700,000	203,100,000
General taxes									70,600,000	56,900,000	49,500,000
Total operating expenses									960,900,000	758,300,000	685,600,000
Gain (loss) on sale of assets									6,600,000	11,900,000	6,700,000
Operating income									1,148,800,000	900,700,000	962,900,000
Equity earnings from investments									-28,800,000	45,500,000	50,300,000
Allowance for equity funds used during construction									14,900,000	30,500,000	13,600,000
Other income (expense), net									1,200,000	9,800,000	5,000,000
Interest expense									-281,900,000	-236,700,000	-206,000,000
Income before income taxes									854,200,000	749,800,000	825,800,000
Income taxes									-12,700,000	-10,800,000	-10,100,000
Net income									841,500,000	739,000,000	815,700,000
Less: Net income attributable to noncontrolling interests									1,000,000	400,000	400,000
Net income attributable to ONEOK Partners, L.P.									840,500,000	738,600,000	815,300,000
Consolidating Entries [Member]
Condensed Financial Statements, Captions [Line Items]
Commodity Sales									0	0	0
Services									0	0	0
Total revenues									0	0	0
Cost of sales and fuel									0	0	0
Net margin									0	0	0
Operating Expenses
Operations and maintenance									0	0	0
Depreciation and amortization									0	0	0
General taxes									0	0	0
Total operating expenses									0	0	0
Gain (loss) on sale of assets									0	0	0
Operating income									0	0	0
Equity earnings from investments									-1,750,800,000	-1,542,200,000	-1,703,300,000
Allowance for equity funds used during construction									0	0	0
Other income (expense), net									-663,400,000	-575,200,000	-480,200,000
Interest expense									663,400,000	575,200,000	480,200,000
Income before income taxes									-1,750,800,000	-1,542,200,000	-1,703,300,000
Income taxes									0	0	0
Net income									-1,750,800,000	-1,542,200,000	-1,703,300,000
Less: Net income attributable to noncontrolling interests									0	0	0
Net income attributable to ONEOK Partners, L.P.									-1,750,800,000	-1,542,200,000	-1,703,300,000
Total [Member]
Condensed Financial Statements, Captions [Line Items]
Commodity Sales									10,725,000,000	10,549,200,000	9,010,200,000
Services									1,466,700,000	1,320,100,000	1,172,000,000
Total revenues									12,191,700,000	11,869,300,000	10,182,200,000
Cost of sales and fuel									10,088,600,000	10,222,200,000	8,540,400,000
Net margin									2,103,100,000	1,647,100,000	1,641,800,000
Operating Expenses
Operations and maintenance									599,100,000	464,700,000	433,000,000
Depreciation and amortization									291,200,000	236,700,000	203,100,000
General taxes									70,600,000	56,900,000	49,500,000
Total operating expenses									960,900,000	758,300,000	685,600,000
Gain (loss) on sale of assets									6,600,000	11,900,000	6,700,000
Operating income									1,148,800,000	900,700,000	962,900,000
Equity earnings from investments									41,000,000	110,500,000	123,000,000
Allowance for equity funds used during construction									14,900,000	30,500,000	13,600,000
Other income (expense), net									1,200,000	9,800,000	5,000,000
Interest expense									-281,900,000	-236,700,000	-206,000,000
Income before income taxes									924,000,000	814,800,000	898,500,000
Income taxes									-12,700,000	-10,800,000	-10,100,000
Net income									911,300,000	804,000,000	888,400,000
Less: Net income attributable to noncontrolling interests									1,000,000	400,000	400,000
Net income attributable to ONEOK Partners, L.P.									910,300,000	803,600,000	888,000,000
Northern Border Pipeline [Member]
Condensed Financial Statements, Captions [Line Items]
Equity Method Investment, Ownership Percentage	50.00%								50.00%
Operating Expenses
Equity earnings from investments									$69,819,000	$65,046,000	$72,705,000

SUPPLEMENTAL_CONDENSED_CONSOLI3

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Comprehensive Income (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Net income	$264,036	$167,320	$214,511	$265,468	$228,444	$216,400	$202,454	$156,685	$911,335	$803,983	$888,428
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives									-64,639	32,141	10,295
Realized (gains) losses on derivatives recognized in net income									31,653	8,344	-58,529
Total other comprehensive income (loss)									-32,986	40,485	-48,234
Comprehensive income									878,349	844,468	840,194
Net Income (Loss) Attributable to Noncontrolling Interest									1,037	357	438
Less: Comprehensive income attributable to noncontrolling interests									1,037	357	438
Comprehensive income attributable to ONEOK Partners, L.P.									877,312	844,111	839,756
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net income									910,300	803,600	888,000
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives									-64,600	32,100	10,300
Realized (gains) losses on derivatives recognized in net income									31,600	8,400	-58,500
Total other comprehensive income (loss)									-33,000	40,500	-48,200
Comprehensive income									877,300	844,100	839,800
Net Income (Loss) Attributable to Noncontrolling Interest									0	0	0
Less: Comprehensive income attributable to noncontrolling interests										0	0
Comprehensive income attributable to ONEOK Partners, L.P.									877,300	844,100	839,800
Guarantor Subsidiary [Member]
Condensed Financial Statements, Captions [Line Items]
Net income									910,300	803,600	888,000
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives									32,400	-14,500	46,800
Realized (gains) losses on derivatives recognized in net income									21,100	-1,700	-61,500
Total other comprehensive income (loss)									53,500	-16,200	-14,700
Comprehensive income									963,800	787,400	873,300
Net Income (Loss) Attributable to Noncontrolling Interest									0	0	0
Less: Comprehensive income attributable to noncontrolling interests										0	0
Comprehensive income attributable to ONEOK Partners, L.P.									963,800	787,400	873,300
Combined Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income									841,500	739,000	815,700
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives									32,400	-14,500	46,800
Realized (gains) losses on derivatives recognized in net income									21,100	-1,700	-61,500
Total other comprehensive income (loss)									53,500	-16,200	-14,700
Comprehensive income									895,000	722,800	801,000
Net Income (Loss) Attributable to Noncontrolling Interest									1,000	400	400
Less: Comprehensive income attributable to noncontrolling interests										400	400
Comprehensive income attributable to ONEOK Partners, L.P.									894,000	722,400	800,600
Consolidating Entries [Member]
Condensed Financial Statements, Captions [Line Items]
Net income									-1,750,800	-1,542,200	-1,703,300
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives									-64,800	29,000	-93,600
Realized (gains) losses on derivatives recognized in net income									-42,200	3,400	123,000
Total other comprehensive income (loss)									-107,000	32,400	29,400
Comprehensive income									-1,857,800	-1,509,800	-1,673,900
Net Income (Loss) Attributable to Noncontrolling Interest									0	0	0
Less: Comprehensive income attributable to noncontrolling interests										0	0
Comprehensive income attributable to ONEOK Partners, L.P.									-1,857,800	-1,509,800	-1,673,900
Total [Member]
Condensed Financial Statements, Captions [Line Items]
Net income									911,300	804,000	888,400
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives									-64,600	32,100	10,300
Realized (gains) losses on derivatives recognized in net income									31,600	8,400	-58,500
Total other comprehensive income (loss)									-33,000	40,500	-48,200
Comprehensive income									878,300	844,500	840,200
Net Income (Loss) Attributable to Noncontrolling Interest									1,000	400	400
Less: Comprehensive income attributable to noncontrolling interests										400	400
Comprehensive income attributable to ONEOK Partners, L.P.									$877,300	$844,100	$839,800

SUPPLEMENTAL_CONDENSED_CONSOLI4

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION CONDENSED CONSOLIDATING FINANCIAL STATEMENTS, Balance Sheet (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current assets
Cash and cash equivalents	$42,530,000	$134,530,000	$537,074,000	$35,091,000
Accounts receivable, net	735,830,000	1,103,130,000
Affiliate receivables	8,553,000	9,185,000
Natural Gas and natural gas liquids in storage	134,134,000	188,286,000
Commodity imbalances	64,788,000	80,481,000
Materials and Supplies	55,833,000	54,112,000
Other current assets	44,385,000	13,379,000
Total current assets	1,086,053,000	1,583,103,000
Property, plant and equipment
Property, plant and equipment	13,377,617,000	10,755,048,000
Accumulated depreciation and amortization	1,842,084,000	1,652,648,000
Net property, plant and equipment	11,535,533,000	9,102,400,000
Investments and other assets
Investments in unconsolidated affiliates	1,132,653,000	1,229,838,000	1,221,405,000
Goodwill and intangible assets	822,358,000	832,180,000
Other assets	57,950,000	115,087,000
Total investments and other assets	2,012,961,000	2,177,105,000
Total assets	14,634,547,000	12,862,608,000	10,959,230,000
Current liabilities
Current maturities of long-term debt	7,650,000	7,650,000
Notes Payable	1,055,296,000	0
Accounts payable	874,692,000	1,255,411,000
Affiliate payables	36,106,000	47,458,000
Commodity imbalances	104,650,000	213,577,000
Accrued interest	91,990,000	92,711,000
Other current liabilities	165,672,000	89,211,000
Total current liabilities	2,336,056,000	1,706,018,000
Long-term debt, excluding current maturities	6,038,379,000	6,044,867,000
Deferred credits and other liabilities	141,337,000	113,027,000
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consoldated subsidiaries	5,950,838,000	4,994,160,000
Noncontrolling interests in consolidated subsidiaries	167,937,000	4,536,000	4,767,000
Total equity	6,118,775,000	4,998,696,000
Total liabilities and equity	14,634,547,000	12,862,608,000
Parent Company [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	1,900,000	4,800,000
Total current assets	1,900,000	4,800,000
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	4,248,000,000	4,336,400,000
Intercompany notes receivable	8,843,300,000	6,638,300,000
Goodwill and intangible assets	0	0
Other assets	36,200,000	92,700,000
Total investments and other assets	13,127,500,000	11,067,400,000
Total assets	13,129,400,000	11,072,200,000
Current liabilities
Current maturities of long-term debt	0	0
Notes Payable	1,055,300,000	0
Accounts payable	0	0
Affiliate payables	0	0
Commodity imbalances	0	0
Accrued interest	92,000,000	92,700,000
Other current liabilities	44,800,000	0
Total current liabilities	1,192,100,000	92,700,000
Intercompany debt	0	0
Long-term debt, excluding current maturities	5,986,500,000	5,985,300,000
Deferred credits and other liabilities	0	0
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consoldated subsidiaries	5,950,800,000	4,994,200,000
Noncontrolling interests in consolidated subsidiaries	0	0
Total equity	5,950,800,000	4,994,200,000
Total liabilities and equity	13,129,400,000	11,072,200,000
Guarantor Subsidiary [Member]
Current assets
Cash and cash equivalents	42,500,000	134,500,000	537,100,000	35,100,000
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	42,500,000	134,500,000
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	5,469,800,000	4,593,100,000
Intercompany notes receivable	7,579,000,000	6,247,100,000
Goodwill and intangible assets	0	0
Other assets	0	0
Total investments and other assets	13,048,800,000	10,840,200,000
Total assets	13,091,300,000	10,974,700,000
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	8,843,300,000	6,638,300,000
Long-term debt, excluding current maturities	0	0
Deferred credits and other liabilities	0	0
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consoldated subsidiaries	4,248,000,000	4,336,400,000
Noncontrolling interests in consolidated subsidiaries	0	0
Total equity	4,248,000,000	4,336,400,000
Total liabilities and equity	13,091,300,000	10,974,700,000
Combined Non-Guarantor Subsidiaries [Member]
Current assets
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	735,800,000	1,103,100,000
Affiliate receivables	8,600,000	9,200,000
Natural Gas and natural gas liquids in storage	134,100,000	188,300,000
Commodity imbalances	64,800,000	80,500,000
Materials and Supplies	55,800,000	54,100,000
Other current assets	42,500,000	8,600,000
Total current assets	1,041,600,000	1,443,800,000
Property, plant and equipment
Property, plant and equipment	13,377,600,000	10,755,000,000
Accumulated depreciation and amortization	1,842,100,000	1,652,600,000
Net property, plant and equipment	11,535,500,000	9,102,400,000
Investments and other assets
Investments in unconsolidated affiliates	746,100,000	825,600,000
Intercompany notes receivable	0	0
Goodwill and intangible assets	822,400,000	832,200,000
Other assets	21,800,000	22,400,000
Total investments and other assets	1,590,300,000	1,680,200,000
Total assets	14,167,400,000	12,226,400,000
Current liabilities
Current maturities of long-term debt	7,700,000	7,700,000
Notes Payable	0	0
Accounts payable	874,700,000	1,255,400,000
Affiliate payables	36,100,000	47,500,000
Commodity imbalances	104,700,000	213,600,000
Accrued interest	0	0
Other current liabilities	120,800,000	89,100,000
Total current liabilities	1,144,000,000	1,613,300,000
Intercompany debt	7,579,000,000	6,247,100,000
Long-term debt, excluding current maturities	51,900,000	59,600,000
Deferred credits and other liabilities	141,300,000	113,000,000
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consoldated subsidiaries	5,083,300,000	4,188,900,000
Noncontrolling interests in consolidated subsidiaries	167,900,000	4,500,000
Total equity	5,251,200,000	4,193,400,000
Total liabilities and equity	14,167,400,000	12,226,400,000
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	-9,331,300,000	-8,525,300,000
Intercompany notes receivable	-16,422,300,000	-12,885,400,000
Goodwill and intangible assets	0	0
Other assets	0	0
Total investments and other assets	-25,753,600,000	-21,410,700,000
Total assets	-25,753,600,000	-21,410,700,000
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	-16,422,300,000	-12,885,400,000
Long-term debt, excluding current maturities	0	0
Deferred credits and other liabilities	0	0
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consoldated subsidiaries	-9,331,300,000	-8,525,300,000
Noncontrolling interests in consolidated subsidiaries	0	0
Total equity	-9,331,300,000	-8,525,300,000
Total liabilities and equity	-25,753,600,000	-21,410,700,000
Total [Member]
Current assets
Cash and cash equivalents	42,500,000	134,500,000	537,100,000	35,100,000
Accounts receivable, net	735,800,000	1,103,100,000
Affiliate receivables	8,600,000	9,200,000
Natural Gas and natural gas liquids in storage	134,100,000	188,300,000
Commodity imbalances	64,800,000	80,500,000
Materials and Supplies	55,800,000	54,100,000
Other current assets	44,400,000	13,400,000
Total current assets	1,086,000,000	1,583,100,000
Property, plant and equipment
Property, plant and equipment	13,377,600,000	10,755,000,000
Accumulated depreciation and amortization	1,842,100,000	1,652,600,000
Net property, plant and equipment	11,535,500,000	9,102,400,000
Investments and other assets
Investments in unconsolidated affiliates	1,132,600,000	1,229,800,000
Intercompany notes receivable	0	0
Goodwill and intangible assets	822,400,000	832,200,000
Other assets	58,000,000	115,100,000
Total investments and other assets	2,013,000,000	2,177,100,000
Total assets	14,634,500,000	12,862,600,000
Current liabilities
Current maturities of long-term debt	7,700,000	7,700,000
Notes Payable	1,055,300,000	0
Accounts payable	874,700,000	1,255,400,000
Affiliate payables	36,100,000	47,500,000
Commodity imbalances	104,700,000	213,600,000
Accrued interest	92,000,000	92,700,000
Other current liabilities	165,600,000	89,100,000
Total current liabilities	2,336,100,000	1,706,000,000
Intercompany debt	0	0
Long-term debt, excluding current maturities	6,038,400,000	6,044,900,000
Deferred credits and other liabilities	141,300,000	113,000,000
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in consoldated subsidiaries	5,950,800,000	4,994,200,000
Noncontrolling interests in consolidated subsidiaries	167,900,000	4,500,000
Total equity	6,118,700,000	4,998,700,000
Total liabilities and equity	$14,634,500,000	$12,862,600,000

SUPPLEMENTAL_CONDENSED_CONSOLI5

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION CONDENSED CONSOLIDATING FINANCIAL STATEMENTS, Cash Flows (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Cash provided by operating activities	$1,309,820,000	$1,007,731,000	$946,053,000
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	-1,745,990,000	-1,939,326,000	-1,560,513,000
Acquisitions	-814,934,000	-394,889,000	0
Payments to Acquire Other Investments	-1,063,000	-35,308,000	-30,768,000
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	21,107,000	31,134,000	35,299,000
Proceeds from Sale of Property, Plant, and Equipment	7,817,000	12,290,000	10,778,000
Net Cash Provided by (Used in) Investing Activities	-2,533,063,000	-2,326,099,000	-1,545,204,000
Financing activities
Cash distributions: General and limited partners	-1,052,245,000	-909,713,000	-760,912,000
Minority Interest Distributions	-549,000	-588,000	-783,000
Proceeds from Issuance of Long-term Debt	0	1,247,822,000	1,295,036,000
Payments of Financing Costs	0	-10,246,000	-9,641,000
Repayments of long-term debt	-7,650,000	-7,650,000	-361,062,000
Issuance of common units, net of issuance costs	1,113,139,000	583,929,000	919,427,000
Contribution from general partner	23,252,000	12,270,000	19,069,000
Cash provided by financing activities	1,131,243,000	915,824,000	1,101,134,000
Change in cash and cash equivalents	-92,000,000	-402,544,000	501,983,000
Cash and cash equivalents at beginning of period	134,530,000	537,074,000	35,091,000
Cash and cash equivalents at end of period	42,530,000	134,530,000	537,074,000
Parent Company [Member]
Operating activities
Cash provided by operating activities	1,155,700,000	870,700,000	760,900,000
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	0	0	0
Acquisitions	0	0
Payments to Acquire Other Investments	0	0	0
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	0	0	0
Proceeds from Sale of Property, Plant, and Equipment	0	0	0
Net Cash Provided by (Used in) Investing Activities	0	0	0
Financing activities
Cash distributions: General and limited partners	-1,052,200,000	-909,700,000	-760,900,000
Minority Interest Distributions	0	0	0
Proceeds from Issuance of Long-term Debt	1,055,300,000	1,247,800,000	1,295,000,000
Payments of Financing Costs		-10,200,000	-9,600,000
Intercompany Borrowings Advances	-2,295,200,000	-1,794,800,000	-1,873,900,000
Repayments of long-term debt	0	0	-350,000,000
Issuance of common units, net of issuance costs	1,113,100,000	583,900,000	919,400,000
Contribution from general partner	23,300,000	12,300,000	19,100,000
Cash provided by financing activities	-1,155,700,000	-870,700,000	-760,900,000
Change in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
Guarantor Subsidiary [Member]
Operating activities
Cash provided by operating activities	69,800,000	65,100,000	72,700,000
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	0	-2,600,000	0
Acquisitions	0	0
Payments to Acquire Other Investments	0	-30,800,000	0
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	17,700,000	19,400,000	23,000,000
Proceeds from Sale of Property, Plant, and Equipment	0	0	0
Net Cash Provided by (Used in) Investing Activities	17,700,000	-14,000,000	23,000,000
Financing activities
Cash distributions: General and limited partners	-1,052,200,000	-909,700,000	-760,900,000
Minority Interest Distributions	0	0	0
Proceeds from Issuance of Long-term Debt	0	0	0
Payments of Financing Costs		0	0
Intercompany Borrowings Advances	872,700,000	456,000,000	1,167,200,000
Repayments of long-term debt	0	0	0
Issuance of common units, net of issuance costs	0	0	0
Contribution from general partner	0	0	0
Cash provided by financing activities	-179,500,000	-453,700,000	406,300,000
Change in cash and cash equivalents	-92,000,000	-402,600,000	502,000,000
Cash and cash equivalents at beginning of period	134,500,000	537,100,000	35,100,000
Cash and cash equivalents at end of period	42,500,000	134,500,000	537,100,000
Combined Non-Guarantor Subsidiaries [Member]
Operating activities
Cash provided by operating activities	1,136,500,000	981,600,000	873,400,000
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	-1,746,000,000	-1,936,700,000	-1,560,500,000
Acquisitions	-814,900,000	-394,900,000
Payments to Acquire Other Investments	-1,000,000	-4,500,000	-30,800,000
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	3,400,000	11,700,000	12,300,000
Proceeds from Sale of Property, Plant, and Equipment	7,800,000	12,300,000	10,800,000
Net Cash Provided by (Used in) Investing Activities	-2,550,700,000	-2,312,100,000	-1,568,200,000
Financing activities
Cash distributions: General and limited partners	0	0	0
Minority Interest Distributions	-600,000	-600,000	-800,000
Proceeds from Issuance of Long-term Debt	0	0	0
Payments of Financing Costs		0	0
Intercompany Borrowings Advances	1,422,500,000	1,338,800,000	706,700,000
Repayments of long-term debt	-7,700,000	-7,700,000	-11,100,000
Issuance of common units, net of issuance costs	0	0	0
Contribution from general partner	0	0	0
Cash provided by financing activities	1,414,200,000	1,330,500,000	694,800,000
Change in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
Consolidating Entries [Member]
Operating activities
Cash provided by operating activities	-1,052,200,000	-909,700,000	-760,900,000
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	0	0	0
Acquisitions	0	0
Payments to Acquire Other Investments	0	0	0
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	0	0	0
Proceeds from Sale of Property, Plant, and Equipment	0	0	0
Net Cash Provided by (Used in) Investing Activities	0	0	0
Financing activities
Cash distributions: General and limited partners	1,052,200,000	909,700,000	760,900,000
Minority Interest Distributions	0	0	0
Proceeds from Issuance of Long-term Debt	0	0	0
Payments of Financing Costs		0	0
Intercompany Borrowings Advances	0	0	0
Repayments of long-term debt	0	0	0
Issuance of common units, net of issuance costs	0	0	0
Contribution from general partner	0	0	0
Cash provided by financing activities	1,052,200,000	909,700,000	760,900,000
Change in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
Total [Member]
Operating activities
Cash provided by operating activities	1,309,800,000	1,007,700,000	946,100,000
Investing activities
Capital expenditures (less allowance for equity funds used during construction)	-1,746,000,000	-1,939,300,000	-1,560,500,000
Acquisitions	-814,900,000	-394,900,000
Payments to Acquire Other Investments	-1,000,000	-35,300,000	-30,800,000
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	21,100,000	31,100,000	35,300,000
Proceeds from Sale of Property, Plant, and Equipment	7,800,000	12,300,000	10,800,000
Net Cash Provided by (Used in) Investing Activities	-2,533,000,000	-2,326,100,000	-1,545,200,000
Financing activities
Cash distributions: General and limited partners	-1,052,200,000	-909,700,000	-760,900,000
Minority Interest Distributions	-600,000	-600,000	-800,000
Proceeds from Issuance of Long-term Debt	1,055,300,000	1,247,800,000	1,295,000,000
Payments of Financing Costs		-10,200,000	-9,600,000
Intercompany Borrowings Advances	0	0	0
Repayments of long-term debt	-7,700,000	-7,700,000	-361,100,000
Issuance of common units, net of issuance costs	1,113,100,000	583,900,000	919,400,000
Contribution from general partner	23,300,000	12,300,000	19,100,000
Cash provided by financing activities	1,131,200,000	915,800,000	1,101,100,000
Change in cash and cash equivalents	-92,000,000	-402,600,000	502,000,000
Cash and cash equivalents at beginning of period	134,500,000	537,100,000	35,100,000
Cash and cash equivalents at end of period	$42,500,000	$134,500,000	$537,100,000