ONEOK Partners (OKS) 10-Q 6 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 29, 2013	Oct. 29, 2013
		Common Units [Member]	Class B Units [Member]
Document Information [Line Items]	'	'	'
Entity Registrant Name	'ONEOK Partners LP	'	'
Entity Central Index Key	'0000909281	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Entity Common Stock, Shares Outstanding	'	158,627,354	72,988,252
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'Q3	'	'
Document Type	'10-Q	'	'
Amendment Flag	'false	'	'
Document Period End Date	30-Sep-13	'	'

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]	'	'	'	'
Revenues	$3,134,733	$2,547,460	$8,420,359	$7,266,354
Cost of sales and fuel	2,711,159	2,127,723	7,214,233	6,024,065
Net margin	423,574	419,737	1,206,126	1,242,289
Operating expenses	'	'	'	'
Operations and maintenance	108,978	110,268	338,353	319,905
Depreciation and amortization	61,182	49,754	174,086	150,024
General taxes	13,384	10,908	46,249	40,505
Total operating expenses	183,544	170,930	558,688	510,434
Gain (loss) on sale of assets	22	-420	342	603
Operating income	240,052	248,387	647,780	732,458
Equity earnings from investments (Note J)	27,468	28,591	79,744	92,380
Allowance for equity funds used during construction	6,429	3,302	21,172	6,126
Other income	3,753	2,971	8,229	6,567
Other expense	-589	-472	-2,447	-2,104
Interest expense (net of capitalized interest of $14,320, $11,328, $38,284 and $29,472, respectively)	-57,722	-47,776	-171,118	-148,110
Income before income taxes	219,391	235,003	583,360	687,317
Income taxes	-2,991	-2,626	-7,821	-9,396
Net income	216,400	232,377	575,539	677,921
Less: Net income attributable to noncontrolling interests	90	102	263	336
Net income attributable to ONEOK Partners, L.P.	216,310	232,275	575,276	677,585
Limited partners' interest in net income:	'	'	'	'
Net income attributable to ONEOK Partners, L.P.	216,310	232,275	575,276	677,585
General partner's interest in net income	-71,344	-59,807	-202,732	-163,210
Limited partners' interest in net income	$144,966	$172,468	$372,544	$514,375
Limited partners' net income per unit, basic and diluted (Note I)	0.64	0.78	1.68	2.38
Number of units used in computation (thousands)	226,991	219,816	222,322	216,241

CONSOLIDATED_STATEMENT_OF_INCO

CONSOLIDATED STATEMENT OF INCOME (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Interest Costs, Capitalized During Period	$14,320	$11,328	$38,284	$29,472

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Other Comprehensive Income [Abstract]	'	'	'	'
Net income	$216,400	$232,377	$575,539	$677,921
Other comprehensive income (loss)	'	'	'	'
Unrealized gains (losses) on derivatives	-3,596	-19,361	38,786	1,637
Realized (gains) losses on derivatives recognized in net income	2,204	-19,852	3,273	-42,647
Total other comprehensive income (loss)	-1,392	-39,213	42,059	-41,010
Comprehensive income	215,008	193,164	617,598	636,911
Less: Comprehensive income attributable to noncontrolling interests	90	102	263	336
Comprehensive income attributable to ONEOK Partners, L.P.	$214,918	$193,062	$617,335	$636,575

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets	'	'
Cash and cash equivalents	$723,030	$537,074
Accounts receivable, net	956,575	914,036
Affiliate receivables	13,227	16,092
Gas and natural gas liquids in storage	390,629	235,836
Commodity imbalances	93,722	89,704
Other current assets	83,829	98,966
Total current assets	2,261,012	1,891,708
Property, plant and equipment	'	'
Property, plant and equipment	10,245,377	8,585,142
Accumulated depreciation and amortization	1,595,814	1,440,871
Net property, plant and equipment	8,649,563	7,144,271
Investments and other assets	'	'
Investments in unconsolidated affiliates (Note J)	1,201,873	1,221,405
Goodwill and intangible assets	640,122	645,871
Other assets	110,756	55,975
Total investments and other assets	1,952,751	1,923,251
Total assets	12,863,326	10,959,230
Current liabilities	'	'
Current maturities of long-term debt	7,650	7,650
Notes payable (Note E)	47,000	0
Accounts payable	1,202,049	1,058,007
Affiliate payables	43,934	75,710
Commodity imbalances	228,207	273,173
Accrued interest	88,545	76,734
Other current liabilities	99,465	79,158
Total current liabilities	1,716,850	1,570,432
Long-term debt, excluding current maturities	6,046,494	4,803,629
Deferred credits and other liabilities	108,087	121,662
Commitments and contingencies (Note L)	'	'
ONEOK Partners, L.P. partners' equity:	'	'
General partner	169,166	152,513
Common units: 158,627,354 and 146,827,354 units issued and outstanding at September 30, 2013, and December 31, 2012, respectively	3,448,986	2,945,051
Class B units: 72,988,252 units issued and outstanding at September 30, 2013, and December 31, 2012	1,426,418	1,460,498
Accumulated other comprehensive loss (Note H)	-57,263	-99,322
Total ONEOK Partners, L.P. partners' equity	4,987,307	4,458,740
Noncontrolling interests in consolidated subsidiaries	4,588	4,767
Total equity	4,991,895	4,463,507
Total liabilities and equity	$12,863,326	$10,959,230

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical)	Sep. 30, 2013	Dec. 31, 2012
ONEOK Partners, L.P. partners equity:	'	'
Common units issued (in units)	158,627,354	146,827,354
Common units outstanding (in units)	158,627,354	146,827,354
Class B units issued (in units)	72,988,252	72,988,252
Class B units outstanding (in units)	72,988,252	72,988,252

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Operating activities	'	'
Net income	$575,539	$677,921
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	174,086	150,024
Allowance for equity funds used during construction	-21,172	-6,126
Gain on sale of assets	-342	-603
Deferred income taxes	5,673	5,863
Equity earnings from investments	-79,744	-92,380
Distributions received from unconsolidated affiliates	79,022	92,996
Changes in assets and liabilities:	'	'
Accounts receivable	-42,539	106,834
Affiliate receivables	2,865	-10,229
Gas and natural gas liquids in storage	-154,793	-125,033
Accounts payable	171,770	-76,592
Affiliate payables	-31,776	3,132
Commodity imbalances, net	-48,984	17,252
Accrued interest	11,811	-2,091
Other assets and liabilities, net	12,702	-120,448
Cash provided by operating activities	654,118	620,520
Investing activities	'	'
Capital expenditures (less allowance for equity funds used during construction)	-1,373,904	-1,011,527
Acquisition	-304,889	0
Contributions to unconsolidated affiliates	-4,558	-21,284
Distributions received from unconsolidated affiliates	24,891	25,756
Proceeds from sale of assets	641	1,663
Cash used in investing activities	-1,657,819	-1,005,392
Financing activities	'	'
Cash distributions: general and limited partners	-669,981	-550,978
Cash distributions: noncontrolling interests	-442	-636
Borrowing of notes payable, net	47,000	0
Issuance of long-term debt, net of discounts	1,247,822	1,295,036
Long-term debt financing costs	-10,217	-9,635
Repayment of long-term debt	-5,738	-358,948
Issuance of common units, net of issuance costs	569,246	919,521
Contribution from general partner	11,967	19,069
Cash provided by financing activities	1,189,657	1,313,429
Change in cash and cash equivalents	185,956	928,557
Cash and cash equivalents at beginning of period	537,074	35,091
Cash and cash equivalents at end of period	$723,030	$963,648

CONSOLIDATED_STATEMENT_OF_CHAN

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (USD $)	Total	General Partner [Member]	Common Units [Member]	Class B Units [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests in Consolidated Subsidiaries [Member]
In Thousands, except Share data
Partners capital account, beginning balance at Dec. 31, 2012	$4,463,507	$152,513	$2,945,051	$1,460,498	($99,322)	$4,767
Partners capital account, units, beginning balance at Dec. 31, 2012	'	'	146,827,354	72,988,252	'	'
Net income	575,539	202,732	250,065	122,479	0	263
Other comprehensive loss (Note H)	42,059	0	0	0	42,059	0
Issuance of common units (in units) (Note G)	'	'	11,800,000	0	'	'
Issuance of common units (Note G)	569,246	0	569,246	0	0	0
Contribution from general partner (Note G)	11,967	11,967	0	0	0	0
Distributions paid (Note G)	-670,423	-198,046	-315,376	-156,559	0	-442
Partners capital account, ending balance at Sep. 30, 2013	$4,991,895	$169,166	$3,448,986	$1,426,418	($57,263)	$4,588
Partners capital account, units, ending balance at Sep. 30, 2013	'	'	158,627,354	72,988,252	'	'

SUMMARY_OF_SIGNIFICANT_ACCOUNT

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	'
	A.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Our accompanying unaudited consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC.  These statements have been prepared in accordance with GAAP and reflect all adjustments that, in our opinion, are necessary for a fair presentation of the results for the interim periods presented.  All such adjustments are of a normal recurring nature.  The 2012 year-end consolidated balance sheet data was derived from our audited financial statements but does not include all disclosures required by GAAP.  These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements in our Annual Report.
	Our significant accounting policies are consistent with those disclosed in Note A of the Notes to Consolidated Financial Statements in our Annual Report.
	Recently Issued Accounting Standards Update - In July 2013, the FASB issued ASU 2013-10, “Inclusion of the Fed Funds Effective Swap Rate (or Overnight Index Swap Rate) as a Benchmark Interest Rate for Hedge Accounting Purposes,” which allows an entity to designate the Fed Funds Effective Swap rate (also known as the Overnight Index Swap rate, or OIS rate, in the United States) as a benchmark interest rate for hedge accounting purposes in addition to the interest rates on direct Treasury obligations of the United States government and the LIBOR. This guidance is effective prospectively for qualifying new or redesigned hedging relationships entered into on or after July 17, 2013. We adopted this guidance with our September 30, 2013, Quarterly Report, and it did not impact materially our financial position or results of operations. See Note D for additional disclosures.
	In February 2013, the FASB issued ASU 2013-02, “Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income,” which requires presentation in a single location, either in a single note or parenthetically on the face of the financial statements, the effect of significant amounts reclassified from each component of accumulated other comprehensive income based on its source. This guidance is effective for our interim and annual periods beginning on January 1, 2013, and is applied prospectively. We adopted this guidance with our March 31, 2013, Quarterly Report, and it did not impact our financial position or results of operations. See Note H for additional disclosures.
	In December 2011, the FASB issued ASU 2011-11, “Disclosures about Offsetting Assets and Liabilities,” which increases disclosures about offsetting assets and liabilities. In January 2013, the FASB issued ASU 2013-01, “Clarifying the Scope of Disclosures about Offsetting Assets and Liabilities,” which clarifies that the scope of ASU 2011-11 applies to derivatives accounted for in accordance with Topic 815, Derivatives and Hedging. New disclosures are required to enable users of financial statements to understand significant quantitative differences in balance sheets prepared under GAAP and International Financial Reporting Standards related to the offsetting of financial instruments, including derivatives. The existing GAAP guidance allowing balance sheet offsetting remains unchanged. This guidance is effective for interim and annual periods beginning on January 1, 2013, and is applied retrospectively for all comparative periods presented. We adopted this guidance beginning with our March 31, 2013, Quarterly Report, and it did not impact our financial position or results of operations. See Note C for additional disclosures.
	Goodwill Impairment Test - We assess our goodwill for impairment at least annually on July 1, unless events or changes in circumstances indicate an impairment may have occurred before that time. At July 1, 2013, we assessed qualitative factors to determine whether it was more likely than not that the fair value of each of our reporting units was less than its carrying amount. After assessing qualitative factors (including macroeconomic conditions, industry and market considerations, cost factors and overall financial performance), we determined that no further testing was necessary.

ACQUISITION

ACQUISITION	9 Months Ended
	Sep. 30, 2013
Acquisition [Abstract]	'
Mergers, Acquisitions and Dispositions Disclosures [Text Block]	'
	B.	ACQUISITION
	On September 30, 2013, we completed the acquisition of a business comprised of natural gas gathering and processing and natural gas liquids facilities in Converse and Campbell counties, Wyoming, in the NGL-rich Niobrara Shale formation of the Powder River Basin for $305 million, subject to customary purchase price adjustments. 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.
	We accounted for this transaction using the acquisition method of accounting, which requires, among other things, that the assets acquired and liabilities assumed be recognized on the balance sheet at their fair values as of the acquisition date. We are developing a preliminary purchase price allocation, which will be adjusted as additional information relative to the fair value of assets and liabilities, which could include intangible assets and goodwill, becomes available. As we have not completed the purchase price allocation for this transaction, we have recorded the purchase price in property, plant and equipment in our consolidated balance sheet at September 30, 2013.

FAIR_VALUE_MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
FAIR VALUE MEASUREMENTS	'
	C.	FAIR VALUE MEASUREMENTS
	Determining Fair Value - We define fair value as the price that would be received from the sale of an asset or the transfer of a liability in an orderly transaction between market participants at the measurement date.  We use the income approach to determine the fair value of our derivative 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, historical correlations of NGL product prices to crude oil prices and implied forward LIBOR curves.  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.  Finally, we consider the credit risk of our counterparties with whom our derivative assets and liabilities are executed.  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.
	Recurring Fair Value Measurements - The following tables set forth our recurring fair value measurements for the periods indicated:
		September 30, 2013
		Level 1			Level 2			Level 3			Total - Gross			Netting (a)			Total - Net (b)
		(Thousands of dollars)
	Derivatives assets
	Commodity contracts
	Financial contracts	$	—		$	15,656		$	5,148		$	20,804		$	(4,436	)	$	16,368
	Physical contracts	—			—			351			351			—			351
	Interest-rate contracts	—			43,614			—			43,614			—			43,614
	Total derivative assets	$	—		$	59,270		$	5,499		$	64,769		$	(4,436	)	$	60,333
	Derivatives liabilities
	Commodity contracts
	Financial contracts	$	—		$	(2,150	)	$	(2,286	)	$	(4,436	)	$	4,436		$	—
	Physical contracts	—			—			(2,712		)	(2,712		)	—			(2,712		)
	Total derivative liabilities	$	—		$	(2,150	)	$	(4,998	)	$	(7,148	)	$	4,436		$	(2,712	)
		December 31, 2012
		Level 1			Level 2			Level 3			Total - Gross			Netting (a)			Total - Net (b)
		(Thousands of dollars)
	Derivatives assets
	Commodity contracts - financial	$	—		$	17,581		$	1		$	17,582		$	(2,455	)	$	15,127
	Interest-rate contracts	—			10,923			—			10,923			—			10,923
	Total derivative assets	$	—		$	28,504		$	1		$	28,505		$	(2,455	)	$	26,050
	Derivatives liabilities
	Commodity contracts - financial	$	—		$	(31	)	$	(2,424	)	$	(2,455	)	$	2,455		$	—
	Total derivative liabilities	$	—		$	(31	)	$	(2,424	)	$	(2,455	)	$	2,455		$	—
	(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.
	(b) - Included in other current assets, other assets or other current liabilities in our Consolidated Balance Sheets.
	At September 30, 2013, and December 31, 2012, we had no cash collateral held or posted under our master-netting arrangements.
	Our Level 1 fair value measurements would include amounts based on unadjusted quoted prices in active markets including NYMEX-settled prices.
	Our Level 2 fair value amounts 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.
	Our Level 3 fair value amounts 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.
	The following table sets forth a reconciliation of our Level 3 fair value measurements for the periods indicated:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	Derivative Assets (Liabilities)	2013			2012			2013			2012
		(Thousands of dollars)
	Net assets (liabilities) at beginning of period	$	7,682		$	29,862		$	(2,423	)	$	3,117
	Total realized/unrealized gains (losses) included in other	(7,181		)	(19,959		)	2,924			6,786
	comprehensive income (loss)
	Net assets at end of period	$	501		$	9,903		$	501		$	9,903
	During the three and nine months ended September 30, 2013 and 2012, gains or losses included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the end of the period were not material. During the three and nine months ended September 30, 2013 and 2012, there were no transfers between levels.
	Other Financial Instruments - The approximate fair value of cash and cash equivalents, accounts receivable, accounts payable and notes payable is equal to book value, due to the short-term nature of these items. Our cash and cash equivalents are comprised of bank and money market accounts and are classified as Level 1. Our notes payable are classified as Level 2 since the estimated fair value of the notes payable can be determined using information available in the commercial paper market.
	The estimated fair value of the aggregate of our senior notes outstanding, including current maturities, was $6.4 billion and $5.6 billion at September 30, 2013, and December 31, 2012, respectively.  The book value of the aggregate of our senior notes outstanding, including current maturities, was $6.1 billion at September 30, 2013, and $4.8 billion at December 31, 2012.  The estimated fair value of the aggregate of our senior notes outstanding was determined using quoted market prices for similar issues with similar terms and maturities.  The estimated fair value of our long-term debt is classified as Level 2.

RISK_MANAGEMENT_AND_HEDGING_AC

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES	9 Months Ended
	Sep. 30, 2013
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 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. This transfers 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.
	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.  Less than 2 percent of our contracted volume exposure arises from the relative price differential between NGLs and natural gas, or the gross processing spread, with respect to our keep-whole 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 minimize 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 September 30, 2013, and December 31, 2012, 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 September 30, 2013, and December 31, 2012, 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 September 30, 2013, and December 31, 2012, we had forward-starting interest-rate swaps with notional amounts totaling $400 million with settlement dates greater than 12 months 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.
	Accounting Treatment - We record all derivative instruments at fair value, with the exception of normal purchases and normal sales that are expected to result in physical delivery.  The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and, if so, the reason for holding it.
	The table below summarizes the various ways in which we account for our derivative instruments and the impact on our consolidated financial statements:
			Recognition and Measurement
	Accounting Treatment		Balance Sheet		Income Statement
	Normal purchases and normal sales	-	Fair value not recorded	-	Change in fair value not recognized in earnings
	Mark-to-market	-	Recorded at fair value	-	Change in fair value recognized in earnings
	Cash flow hedge	-	Recorded at fair value	-	Ineffective portion of the gain or loss on the
					derivative instrument is recognized in earnings
		-	Effective portion of the gain or loss on the	-	Effective portion of the gain or loss on the
			derivative instrument is reported initially		derivative instrument is reclassified out of
			as a 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
	Under certain conditions, we designate our derivative instruments as a hedge of exposure to changes in fair values or cash flows.  We formally document all relationships between hedging instruments and hedged items, as well as risk-management objectives, 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 with a cash flow hedge.  We assess the effectiveness of hedging relationships quarterly by performing an effectiveness analysis on our fair value and cash flow hedging relationships to determine whether the hedge relationships are highly effective on a retrospective and prospective basis.  We also document our normal purchases and normal sales transactions that we expect to result in physical delivery and that we elect to exempt from derivative accounting treatment.
	The realized revenues and purchase costs of our derivative instruments not considered held for trading purposes and derivatives that qualify as normal purchases or normal sales that are expected to result in physical delivery are reported on a gross basis.
	Cash flows from futures, forwards and swaps that are accounted for as hedges are included in the same category as the cash flows from the related hedged items in our Consolidated Statements of Cash Flows.
	Fair Values of Derivative Instruments - See Note C for a discussion of the inputs associated with our fair value measurements. The following table sets forth the fair values of our derivative instruments, all of which were designated as cash flow hedges for the periods indicated:
		September 30, 2013								December 31, 2012
		Assets (a)				(Liabilities) (a)				Assets (b)				(Liabilities) (b)
		(Thousands of dollars)
	Commodity contracts - financial	$	20,804			$	(4,436	)		$	17,582			$	(2,455	)
	Commodity contracts - physical	351				(2,712		)		—				—
	Interest-rate contracts	43,614				—				10,923				—
	Total derivatives designated as hedging instruments	$	64,769			$	(7,148	)		$	28,505			$	(2,455	)
	(a) - Included on a net basis in other current assets, other assets or other current liabilities on our Consolidated Balance Sheets.
	(b) - Included on a net basis in other current assets or other assets on our Consolidated Balance Sheets.
	Notional Quantities for Derivative Instruments - The following table sets forth the notional quantities for derivative instruments designated as hedging instruments for the periods indicated:
			30-Sep-13								December 31, 2012
		Contract	Purchased/				Sold/				Purchased/				Sold/
		Type	Payor				Receiver				Payor				Receiver
	Cash flow hedges
	Fixed price
	- Natural gas (Bcf)	Swaps	—				(49.4		)		—				(31.7		)
	- Crude oil and NGLs (MMbbl)	Forwards and swaps	—				(2.3		)		—				(1.1		)
	Basis
	- Natural gas (Bcf)	Swaps	—				(49.4		)		—				(31.7		)
	Interest-rate contracts (Millions of dollars)	Forward-starting	$	400			$	—			$	400			$	—
		swaps
	Cash Flow Hedges - At September 30, 2013, our Consolidated Balance Sheet reflected a net unrealized loss of $57.3 million in accumulated other comprehensive loss.  The portion of accumulated other comprehensive loss attributable to our commodity derivative instruments is a gain of $14.0 million, which will be realized within the next 27 months as the forecasted transactions affect earnings. If commodity prices remain at the current levels, we will recognize $6.1 million in gains over the next 12 months and $7.9 million in gains thereafter.  The amount deferred in accumulated other comprehensive income (loss) attributable to our settled interest-rate swaps is a loss of $112.1 million, which will be recognized over the life of the long-term, fixed-rate debt. We expect that losses of $10.1 million will be reclassified into earnings during the next 12 months as the hedged items affect earnings. The remaining amounts in accumulated other comprehensive income (loss) are attributable primarily to forward-starting interest-rate swaps with settlement dates greater than 12 months, 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 effect of cash flow hedges recognized in other comprehensive income (loss) for the periods indicated:
		Three Months Ended								Nine Months Ended
	Derivatives in Cash Flow	September 30,								September 30,
	Hedging Relationships	2013				2012				2013				2012
		(Thousands of dollars)
	Commodity contracts	$	(10,317	)		$	(18,186	)		$	3,060			$	41,469
	Interest-rate contracts	6,721				(1,175		)		35,726				(39,832		)
	Total unrealized gain (loss) recognized in other comprehensive	$	(3,596	)		$	(19,361	)		$	38,786			$	1,637
	loss (effective portion)
	The following table sets forth the effect of cash flow hedges in our Consolidated Statements of Income for the periods indicated:
Derivatives in Cash Flow	Location of Gain (Loss) Reclassified from	Three Months Ended								Nine Months Ended
Hedging Relationships	Accumulated Other Comprehensive Income	September 30,								September 30,
	(Loss) into Net Income (Effective Portion)	2013				2012				2013				2012
		(Thousands of dollars)
Commodity contracts	Revenues	$	361			$	20,549			$	4,172			$	43,527
Interest-rate contracts	Interest expense	(2,565		)		(697		)		(7,445		)		(880		)
Total gain (loss) reclassified from accumulated other comprehensive loss		$	(2,204	)		$	19,852			$	(3,273	)		$	42,647
into net income (effective portion)
Ineffectiveness related to our cash flow hedges was not material for the three and nine months ended September 30, 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 the three and nine months ended September 30, 2013 and 2012.
Credit Risk - All of our commodity derivative financial contracts are with our affiliate ONEOK Energy Services Company, a subsidiary of ONEOK. ONEOK Energy Services Company has entered into similar commodity derivative financial contracts with third parties at our direction and on our behalf.  We have an indemnification agreement with ONEOK Energy Services Company that indemnifies and holds it harmless from any liability it may incur solely as a result of its entering into commodity derivative financial contracts on our behalf. ONEOK announced an accelerated wind down of ONEOK Energy Services Company operations that is expected to be substantially completed by April 2014. We expect to enter into commodity derivative financial contracts with unaffiliated third parties or ONEOK affiliates after the wind down is completed. Net derivative asset positions for which we would indemnify ONEOK Energy Services Company in the event of a default by the counterparty were with investment-grade counterparties that are primarily in the financial services and oil and gas sectors. Our interest-rate derivatives are with investment-grade financial institutions.

CREDIT_FACILITY_AND_SHORTTERM_

CREDIT FACILITY AND SHORT-TERM NOTES PAYABLE	9 Months Ended
	Sep. 30, 2013
Short-term Debt [Abstract]	'
CREDIT FACILITY AND SHORT-TERM NOTES PAYABLE	'
	E.	CREDIT FACILITY AND SHORT-TERM NOTES PAYABLE
	Partnership Credit Agreement - Our Partnership Credit Agreement contains certain financial, operational and legal covenants. Among other things, these covenants include maintaining a ratio of indebtedness to adjusted EBITDA (EBITDA, as defined in our Partnership Credit Agreement, adjusted for all noncash charges and increased for projected EBITDA from certain lender-approved capital expansion projects) of no more than 5.0 to 1.  If we consummate one or more acquisitions in which the aggregate purchase price is $25 million or more, the allowable ratio of indebtedness to adjusted EBITDA will increase to 5.5 to 1 for the quarter of the acquisition and the two following quarters.  As a result of our Sage Creek acquisition on September 30, 2013, the allowable ratio of indebtedness to adjusted EBITDA increased to 5.5 to1 for the current quarter and will remain at that level through the first quarter 2014. Upon breach of certain covenants by us in our Partnership Credit Agreement, amounts outstanding under our Partnership Credit Agreement, if any, may become due and payable immediately.  At September 30, 2013, our ratio of indebtedness to adjusted EBITDA was 4.2 to 1, and we were in compliance with all covenants under our Partnership Credit Agreement.
	Our Partnership Credit Agreement includes a $100 million sublimit for the issuance of standby letters of credit and also features an option to request an increase in the size of the facility to an aggregate of $1.7 billion from $1.2 billion by either commitments from new lenders or increased commitments from existing lenders.  Our Partnership Credit Agreement is available for general partnership purposes, including repayment of our commercial paper notes, if necessary.  Amounts outstanding under our commercial paper program reduce the borrowing capacity under our Partnership Credit Agreement.  At September 30, 2013, we had $47.0 million in commercial paper outstanding, no letters of credit issued and no borrowings 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. Borrowings, if any, will accrue at LIBOR plus 130 basis points, and the annual facility fee is 20 basis points based on our current credit rating. Our Partnership Credit Agreement is guaranteed fully and unconditionally by the Intermediate Partnership. Borrowings under our Partnership Credit Agreement are nonrecourse to ONEOK.

LONGTERM_DEBT

LONG-TERM DEBT	9 Months Ended
	Sep. 30, 2013
Long-term Debt, Unclassified [Abstract]	'
Long-term Debt [Text Block]	'
	F.	LONG-TERM DEBT
	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 will be used for general partnership purposes, including but not limited to capital expenditures.
	These notes are governed by an indenture, dated as of September 25, 2006, between us and Wells Fargo Bank, N.A., the trustee, as supplemented.  The indenture does not limit the aggregate principal amount of debt securities that may be issued and provides that debt securities may be issued from time to time in one or more additional series.  The indenture contains covenants including, among other provisions, limitations on our ability to place liens on our property or assets and to sell and lease back our property.  The indenture includes an event of default upon acceleration of other indebtedness of $100 million or more.  Such events of default would entitle the trustee or the holders of 25 percent in aggregate principal amount of any of our outstanding senior notes to declare those notes immediately due and payable in full.
	We may redeem our 3.2 percent senior notes due 2018, our 5.0 percent senior notes due 2023, and our 6.2 percent senior notes due 2043 from the September 2013 offering 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 structurally subordinate to any of the existing and future debt and other liabilities of any nonguarantor subsidiaries.
	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.

EQUITY

EQUITY	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
EQUITY	'
	G.	EQUITY
	ONEOK - ONEOK and its affiliates own 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 41.3 percent ownership interest in us at September 30, 2013.
	Equity Issuances - 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 $1.2 billion commercial paper program and the balance was used 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 up to an aggregate amount of $300 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 the three months ended March 31, 2013, we sold common units through this program that resulted in net proceeds, including ONEOK Partners GP’s contribution to maintain its 2 percent general partner interest in us, of approximately $16.3 million. We used the proceeds for general partnership purposes. We did not sell any units under this program in the second or third quarter 2013.
	As a result of these transactions, ONEOK’s aggregate ownership interest in us decreased to 41.3 percent at September 30, 2013, from 43.4 percent at December 31, 2012.
	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 - In October 2013, our general partner declared a cash distribution of $0.725 per unit ($2.90 per unit on an annualized basis) for the third quarter of 2013, an increase of 0.5 cents from the previous quarter, which will be paid on November 14, 2013, to unitholders of record at the close of business on November 4, 2013.
	The following table shows our distributions paid in the periods indicated:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(Thousands, except per unit amounts)
	Distribution per unit	$	0.72	$	0.66	$	2.145	$	1.905
	General partner distributions	$	4,512	$	3,979	$	13,399	$	11,019
	Incentive distributions	62,634		49,886		184,647		130,968
	Distributions to general partner	67,146		53,865		198,046		141,987
	Limited partner distributions to ONEOK	66,807		61,240		199,031		171,882
	Limited partner distributions to other unitholders	91,676		83,838		272,904		237,109
	Total distributions paid	$	225,629	$	198,943	$	669,981	$	550,978
	The following table shows our distributions declared for the periods indicated and paid within 45 days of the end of the period:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(Thousands, except per unit amounts)
	Distribution per unit	$	0.725	$	0.685	$	2.16	$	1.98
	General partner distributions	$	4,795	$	4,199	$	13,776	$	11,937
	Incentive distributions	67,017		55,162		191,226		149,658
	Distributions to general partner	71,812		59,361		205,002		161,595
	Limited partner distributions to ONEOK	67,271		63,560		200,422		183,721
	Limited partner distributions to other unitholders	100,650		87,014		283,365		251,514
	Total distributions declared	$	239,733	$	209,935	$	688,789	$	596,830

ACCUMULATED_OTHER_COMPREHENSIV

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Notes)	9 Months Ended
	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Abstract]	'
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	'
	H.	ACCUMULATED OTHER COMPREHENSIVE LOSS
	The following table sets forth the balance in accumulated other comprehensive income (loss) for the period indicated:
			Accumulated
			Other
			Comprehensive
			Loss (a)
			(Thousands of dollars)
	1-Jan-13		$	(99,322	)
	Other comprehensive income (loss) before reclassifications		38,786
	Amounts reclassified from accumulated other comprehensive income (loss)		3,273
	Net current-period other comprehensive income (loss) attributable to ONEOK Partners		42,059
	30-Sep-13		$	(57,263	)
	(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		Three Months Ended			Nine Months Ended			Affected Line Item in the
		Comprehensive Income (Loss) Components		30-Sep-13			30-Sep-13			Consolidated Statements of Income
				(Thousand of dollars)
		Unrealized (gains) losses on risk-management
		assets/liabilities
		Commodity contracts		$	(361	)	$	(4,172	)	Revenues
		Interest-rate contracts		2,565			7,445			Interest expense
		Total reclassifications for the period		$	2,204		$	3,273		Net income attributable to ONEOK
		attributable to ONEOK Partners								Partners

LIMITED_PARTNERS_NET_INCOME_PE

LIMITED PARTNERS' NET INCOME PER UNIT	9 Months Ended
	Sep. 30, 2013
Limited Partners' Net Income Per Unit and Distributions to Partners [Abstract]	'
LIMITED PARTNERS' NET INCOME PER UNIT	'
	I.	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, each Class B unit and common unit currently share equally in the earnings of the partnership, and neither has any liquidation or other preferences.
	ONEOK Partners GP owns the entire 2 percent general partnership interest in us, which entitles it to incentive distribution rights that provide for an increasing proportion of cash distributions from the partnership as the distributions made to limited partners increase above specified levels.  For purposes of our calculation of limited partners’ net income per unit, net income attributable to ONEOK Partners, L.P. is allocated to the general partner as follows:  (i) an amount based upon the 2 percent general partner interest in net income attributable to ONEOK Partners, L.P.; and (ii) the amount of the general partner’s incentive distribution rights based on the total cash distributions declared for the period.
	The terms of our Partnership Agreement limit the general partner’s incentive distribution to the amount of available cash calculated for the period.  As such, incentive distribution rights are not allocated on undistributed earnings or distributions in excess of earnings.  For additional information regarding our general partner’s incentive distribution rights, see “Partnership Agreement” in Note H of the Notes to Consolidated Financial Statements in our Annual Report.

UNCONSOLIDATED_AFFILIATES

UNCONSOLIDATED AFFILIATES	9 Months Ended
	Sep. 30, 2013
Equity Method Investments and Joint Ventures [Abstract]	'
UNCONSOLIDATED AFFILIATES	'
	J.	UNCONSOLIDATED AFFILIATES
	Equity Earnings from Investments - The following table sets forth our equity earnings from investments for the periods indicated:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(Thousands of dollars)
	Northern Border Pipeline	$	16,464	$	18,185	$	48,133	$	54,493
	Overland Pass Pipeline Company	5,783		4,490		14,210		15,786
	Fort Union Gas Gathering	2,946		4,091		9,895		11,494
	Bighorn Gas Gathering	559		1,157		1,897		3,118
	Other	1,716		668		5,609		7,489
	Equity earnings from investments	$	27,468	$	28,591	$	79,744	$	92,380
	Unconsolidated Affiliates Financial Information - The following table sets forth summarized combined financial information of our unconsolidated affiliates for the periods indicated:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(Thousands of dollars)
	Income Statement
	Operating revenues	$	131,959	$	125,828	$	391,912	$	373,038
	Operating expenses	$	63,971	$	60,937	$	189,366	$	173,232
	Net income	$	61,630	$	55,721	$	185,580	$	180,787
	Distributions paid to us	$	34,409	$	34,557	$	103,913	$	118,752
	We incurred expenses in transactions with unconsolidated affiliates of $15.9 million and $9.0 million for the three months ended September 30, 2013 and 2012, respectively, and $36.3 million and $27.3 million for the nine months ended September 30, 2013 and 2012, respectively, primarily related to Overland Pass Pipeline Company, which are included in cost of sales and fuel in our Consolidated Statements of Income. Accounts payable to our equity method investees at September 30, 2013, and December 31, 2012, were not material.
	In January 2013, the FERC approved a settlement between Northern Border Pipeline and its customers that modified its transportation rates, effective January 1, 2013. The new long-term transportation rates are approximately 11 percent lower than previous rates, which reduced our equity earnings and cash distributions in the three and nine months ended September 30, 2013, compared with the same periods last year, and are expected to reduce equity earnings and cash distributions from Northern Border Pipeline in the future.
	Low natural gas prices and the relatively higher crude oil and NGL prices, compared with natural gas on a heating-value basis, have caused producers primarily to focus 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 will be affected by commodity prices and producers’ alternative prospects.
	Due to recent reductions in producer activity and declines in natural gas volumes gathered in the Powder River Basin on the Bighorn Gas Gathering system, in which we own a 49 percent equity interest, we tested our investment for impairment at March 31, 2013. The estimated fair value exceeded the carrying value; however, a decline of 10 percent or more in the fair value of our investment in Bighorn Gas Gathering would result in a noncash impairment charge. We were not able to reasonably estimate a range of potential future impairment charges, as many of the assumptions that would be used in our estimate of fair value are dependent upon events beyond our control. There were no impairment indicators identified in the third quarter 2013. The carrying amount of our investment at September 30, 2013, was $88.7 million, which includes $53.4 million in equity method goodwill.

RELATEDPARTY_TRANSACTIONS

RELATED-PARTY TRANSACTIONS	9 Months Ended
	Sep. 30, 2013
Related Party Transactions [Abstract]	'
RELATED-PARTY TRANSACTIONS	'
	K.	RELATED-PARTY TRANSACTIONS
	Intersegment and affiliate sales are recorded on the same basis as sales to unaffiliated customers.  Our Natural Gas Gathering and Processing segment sells natural gas to ONEOK and its subsidiaries.  Our Natural Gas Pipelines segment provides transportation and storage services to ONEOK and its subsidiaries. Additionally, our Natural Gas Gathering and Processing segment and Natural Gas Liquids segment purchase a portion of the natural gas used in their operations from ONEOK and its subsidiaries.
	We have transactions with our affiliate ONEOK Energy Services Company, a subsidiary of ONEOK. In June 2013, ONEOK announced an accelerated wind down of ONEOK Energy Services Company operations that is expected to be substantially completed by April 2014. We expect to continue providing our customers midstream services, including marketing natural gas, NGLs and condensate as a service for third parties or other ONEOK affiliates.
	Our derivative contracts with ONEOK Energy Services Company are discussed under “Credit Risk” in Note D.
	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 and ONEOK Services Company 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.  For example, a service that applies equally to all employees is allocated based upon the number of employees; however, an expense benefiting the consolidated company but having no direct basis for allocation is allocated by the modified Distrigas method, a method using a combination of ratios that includes gross plant and investment, operating income and payroll expense.  It is not practicable to determine what these general overhead costs would be on a stand-alone basis.  All costs directly charged or allocated to us are included in our Consolidated Statements of Income.
	The following table sets forth the transactions with related parties for the periods indicated:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(Thousands of dollars)
	Revenues	$	81,324	$	91,096	$	255,298	$	247,851
	Expenses
	Cost of sales and fuel	$	9,562	$	7,831	$	27,855	$	22,875
	Administrative and general expenses	58,549		60,020		192,906		179,017
	Total expenses	$	68,111	$	67,851	$	220,761	$	201,892
	ONEOK Partners GP made additional general partner contributions to us of approximately $12 million and $19 million during the nine months ended September 30, 2013 and 2012, respectively, to maintain its 2 percent general partner interest in connection with the issuances of common units.  See Note G for additional information about our equity issuances and cash distributions paid to ONEOK for its general partner and limited partner interests.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]	'
COMMITMENTS AND CONTINGENCIES	'
	L.	COMMITMENTS AND CONTINGENCIES
	Environmental Matters - We are subject to multiple historical preservation, wildlife preservation and environmental laws and/or regulations that affect many aspects of our present and future operations.  Regulated activities include, but are not limited to, those involving air emissions, storm water and wastewater discharges, handling and disposal of solid and hazardous wastes, 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, emission 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 issued the President’s Climate Action Plan, which includes, among other things, plans for further regulatory actions to reduce carbon emissions from various sources. The impact of any such regulatory actions on our facilities and operations is unknown. Revised or additional statutes or regulations that result in increased compliance costs or additional operating restrictions could have a significant impact on our business, financial position, results of operations and cash flows.
	Our expenditures for environmental assessment, mitigation, remediation and compliance to date have not been significant in relation to our financial position, results of operations or cash flows, and our expenditures related to environmental matters have had no material effects on earnings or cash flows during the three and nine months ended September 30, 2013, or in 2012.
	The EPA’s “Tailoring Rule” regulates greenhouse gas emissions at new or modified facilities that meet certain criteria. Affected facilities are required to review best available control technology, 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.  The EPA has stated it will consider lowering the threshold levels over the next five years, which could increase the impact on our existing facilities; however, potential costs, fees or expenses associated with the potential adjustments are unknown.
	The EPA’s rule on air-quality standards, titled “National Emissions Standards for Hazardous Air Pollutants for Reciprocating Internal Combustion Engines,” also known as RICE NESHAP, initially included a compliance date in 2013.  Subsequent industry appeals and settlements with the EPA have extended timelines for compliance associated with the final RICE NESHAP rule. While the rule could require capital expenditures for the purchase and installation of new emissions-control equipment, we do not expect these expenditures will have a material impact on our results of operations, financial position or cash flows.
	In July 2011, the EPA issued a proposed rule that would change the air emission 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.
	In March 2013, the EPA issued proposed rulemaking to amend the NSPS for the crude oil and natural gas industry, pursuant to various industry comments, administrative petitions for reconsideration and/or judicial appeals of portions of the NSPS final rule. Beyond the March 2013 proposed amendments, the EPA indicated it would provide additional responses, amendments and/or policy guidance to amend or clarify other portions of the final rule in 2013. The rule was most recently amended in September 2013. Based on the amendments and our understanding of pending stakeholder responses to the NSPS rule, we anticipate a reduction in 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 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.
	Financial Markets Legislation - The Dodd-Frank Act represents a far-reaching overhaul of the framework for regulation of United States financial markets. The CFTC has issued final regulations for most of the provisions of the Dodd-Frank Act, and we have implemented measures to comply with the regulations that are applicable to our businesses. We expect to be able to continue to participate in financial markets for hedging certain risks inherent in our business, including commodity-price and interest-rate risks; however, the capital requirements and costs of hedging may increase as a result of the regulations. These requirements could affect adversely market liquidity and pricing of derivative contracts, making it more difficult to execute our risk-management strategies in the future. Also, the anticipated increased costs of compliance by dealers and counterparties likely will be passed on to customers, which could decrease the benefits of hedging to us and could reduce our profitability and liquidity.
	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	9 Months Ended
	Sep. 30, 2013
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]	'
SEGMENTS	'
	M.	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 of the Notes to Consolidated Financial Statements in our Annual Report.  Intersegment and affiliate sales are recorded on the same basis as sales to unaffiliated customers.  Net margin is comprised of total revenues less cost of sales and fuel.  Cost of sales and fuel includes commodity purchases, fuel and transportation costs.
	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. Customers served by our Natural Gas Pipelines segment include natural gas distribution companies, electric-generation companies, natural gas marketing companies, natural gas producers and petrochemical companies.
	For the three and nine months ended September 30, 2013 and 2012, we had no single customer from which we received 10 percent or more of our consolidated revenues.
	Operating Segment Information - The following tables set forth certain selected financial information for our operating segments for the periods indicated:
	Three Months Ended	Natural Gas		Natural Gas			Natural Gas			Other and			Total
	30-Sep-13	Gathering and		Liquids (a)			Pipelines (b)			Eliminations
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	162,677	$	2,840,108		$	50,624		$	—		$	3,053,409
	Sales to affiliated customers	57,400		—			23,924			—			81,324
	Intersegment revenues	312,940		34,740			1,330			(349,010		)	—
	Total revenues	$	533,017	$	2,874,848		$	75,878		$	(349,010	)	$	3,134,733
	Net margin	$	130,882	$	226,242		$	69,457		$	(3,007	)	$	423,574
	Operating costs	45,074		57,010			23,457			(3,179		)	122,362
	Depreciation and amortization	27,356		22,993			10,833			—			61,182
	Gain (loss) on sale of assets	31		7			(16		)	—			22
	Operating income	$	58,483	$	146,246		$	35,151		$	172		$	240,052
	Equity earnings from investments	$	4,668	$	6,336		$	16,464		$	—		$	27,468
	Capital expenditures	$	204,542	$	230,780		$	11,148		$	2,602		$	449,072
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $147.1 million, of which $130.2 million related to sales within the segment, net margin of $89.5 million and operating income of $53.4 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $57.5 million, net margin of $52.8 million and operating income of $22.6 million.
	Three Months Ended	Natural Gas		Natural Gas			Natural Gas			Other and			Total
	30-Sep-12	Gathering and		Liquids (a)			Pipelines (b)			Eliminations
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	114,127	$	2,287,191		$	55,046		$	—		$	2,456,364
	Sales to affiliated customers	67,269		—			23,827			—			91,096
	Intersegment revenues	197,733		23,777			910			(222,420		)	—
	Total revenues	$	379,129	$	2,310,968		$	79,783		$	(222,420	)	$	2,547,460
	Net margin	$	115,869	$	234,546		$	71,402		$	(2,080	)	$	419,737
	Operating costs	39,371		56,756			26,265			(1,216		)	121,176
	Depreciation and amortization	19,565		18,588			11,592			9			49,754
	Gain (loss) on sale of assets	25		(362		)	(83		)	—			(420		)
	Operating income	$	56,958	$	158,840		$	33,462		$	(873	)	$	248,387
	Equity earnings from investments	$	5,546	$	4,731		$	18,314		$	—		$	28,591
	Capital expenditures	$	157,714	$	212,331		$	5,119		$	127		$	375,291
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $119.2 million, of which $103.7 million related to sales within the segment, net margin of $68.0 million and operating income of $40.8 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $62.4 million, net margin of $54.9 million and operating income of $22.8 million.
	Nine Months Ended	Natural Gas		Natural Gas			Natural Gas			Other and			Total
	30-Sep-13	Gathering and		Liquids (a)			Pipelines (b)			Eliminations
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	466,631	$	7,539,470		$	158,960		$	—		$	8,165,061
	Sales to affiliated customers	179,636		—			75,662			—			255,298
	Intersegment revenues	806,523		91,161			2,327			(900,011		)	—
	Total revenues	$	1,452,790	$	7,630,631		$	236,949		$	(900,011	)	$	8,420,359
	Net margin	$	365,436	$	632,087		$	211,224		$	(2,621	)	$	1,206,126
	Operating costs	141,737		171,076			75,608			(3,819		)	384,602
	Depreciation and amortization	76,366		65,033			32,687			—			174,086
	Gain (loss) on sale of assets	344		10			(12		)	—			342
	Operating income	$	147,677	$	395,988		$	102,917		$	1,198		$	647,780
	Equity earnings from investments	$	16,228	$	15,383		$	48,133		$	—		$	79,744
	Investments in unconsolidated affiliates	$	331,124	$	494,702		$	376,047		$	—		$	1,201,873
	Total assets	$	3,808,135	$	6,610,205		$	1,786,413		$	658,573		$	12,863,326
	Noncontrolling interests in consolidated subsidiaries	$	4,574	$	—		$	—		$	14		$	4,588
	Capital expenditures	$	574,509	$	774,284		$	22,497		$	2,614		$	1,373,904
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $376.9 million, of which $321.3 million related to sales within the segment, net margin of $227.8 million and operating income of $129.0 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $182.0 million, net margin of $162.5 million and operating income of $67.0 million.
Nine Months Ended	Natural Gas		Natural Gas			Natural Gas			Other and			Total
30-Sep-12	Gathering and		Liquids (a)			Pipelines (b)			Eliminations
	Processing
	(Thousands of dollars)
Sales to unaffiliated customers	$	307,145	$	6,554,291		$	157,067		$	—		$	7,018,503
Sales to affiliated customers	177,213		—			70,638			—			247,851
Intersegment revenues	588,379		55,902			2,788			(647,069		)	—
Total revenues	$	1,072,737	$	6,610,193		$	230,493		$	(647,069	)	$	7,266,354
Net margin	$	332,305	$	703,657		$	212,002		$	(5,675	)	$	1,242,289
Operating costs	120,857		166,622			78,291			(5,360		)	360,410
Depreciation and amortization	61,335		54,155			34,525			9			150,024
Gain (loss) on sale of assets	1,154		(456		)	(95		)	—			603
Operating income	$	151,267	$	482,424		$	99,091		$	(324	)	$	732,458
Equity earnings from investments	$	21,031	$	16,378		$	54,971		$	—		$	92,380
Investments in unconsolidated affiliates	$	323,503	$	488,308		$	406,471		$	—		$	1,218,282
Total assets	$	2,797,692	$	5,169,516		$	1,855,209		$	970,176		$	10,792,593
Noncontrolling interests in consolidated subsidiaries	$	—	$	—		$	4,797		$	15		$	4,812
Capital expenditures	$	435,122	$	561,492		$	14,584		$	329		$	1,011,527
(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $333.9 million, of which $285.8 million related to sales within the segment, net margin of $197.2 million and operating income of $115.5 million.
(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $179.1 million, net margin of $162.5 million and operating income of $66.8 million.

SUPPLEMENTAL_CONDENSED_CONSOLI

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION	9 Months Ended
	Sep. 30, 2013
Condensed Financial Information of Parent Company Only Disclosure [Abstract]	'
Supplemental Condensed Consolidating Financial Information	'
	N.	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.  The Intermediate Partnership’s guarantee is full and unconditional, subject to certain customary automatic release provisions.
	For purposes of the following footnote:
	•	we are referred to as “Parent”;
	•	the Intermediate Partnership is referred to as “Guarantor Subsidiary”; and
	•	the “Non-Guarantor Subsidiaries” are all subsidiaries other than the Guarantor Subsidiary.
	The following unaudited supplemental condensed consolidating financial information is presented on an equity method basis reflecting the Parent’s separate accounts, the Guarantor Subsidiary’s separate accounts, the combined accounts of the Non-Guarantor Subsidiaries, the combined consolidating adjustments and eliminations and the Parent’s consolidated amounts for the periods indicated. We have recast prior-period amounts in the condensed consolidating statements of cash flows to revise the classification of dividends received by the Parent from the Guarantor Subsidiary from financing to operating activities.
	Condensed Consolidating Statements of Income
		Three Months Ended September 30, 2013
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Revenues	$	—		$	—		$	3,134.70		$	—		$	3,134.70
	Cost of sales and fuel	—			—			2,711.10			—			2,711.10
	Net margin	—			—			423.6			—			423.6
	Operating expenses
	Operations and maintenance	—			—			109			—			109
	Depreciation and amortization	—			—			61.2			—			61.2
	General taxes	—			—			13.3			—			13.3
	Total operating expenses	—			—			183.5			—			183.5
	Operating income	—			—			240.1			—			240.1
	Equity earnings from investments	216.3			216.3			11			(416.1		)	27.5
	Allowance for equity funds used during	—			—			6.4			—			6.4
	construction
	Other income (expense), net	70.6			70.6			3.1			(141.2		)	3.1
	Interest expense	(70.6		)	(70.6		)	(57.7		)	141.2			(57.7		)
	Income before income taxes	216.3			216.3			202.9			(416.1		)	219.4
	Income taxes	—			—			(3.0		)	—			(3.0		)
	Net income	216.3			216.3			199.9			(416.1		)	216.4
	Less: Net income attributable to noncontrolling	—			—			0.1			—			0.1
	interests
	Net income attributable to ONEOK Partners, L.P.	$	216.3		$	216.3		$	199.8		$	(416.1	)	$	216.3
		Three Months Ended September 30, 2012
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Revenues	$	—		$	—		$	2,547.50		$	—		$	2,547.50
	Cost of sales and fuel	—			—			2,127.80			—			2,127.80
	Net margin	—			—			419.7			—			419.7
	Operating expenses
	Operations and maintenance	—			—			110.3			—			110.3
	Depreciation and amortization	—			—			49.7			—			49.7
	General taxes	—			—			10.9			—			10.9
	Total operating expenses	—			—			170.9			—			170.9
	Loss on sale of assets	—			—			(0.4		)	—			(0.4		)
	Operating income	—			—			248.4			—			248.4
	Equity earnings from investments	232.3			232.3			10.4			(446.4		)	28.6
	Allowance for equity funds used during	—			—			3.3			—			3.3
	construction
	Other income (expense), net	46.2			46.2			2.5			(92.4		)	2.5
	Interest expense	(46.2		)	(46.2		)	(47.8		)	92.4			(47.8		)
	Income before income taxes	232.3			232.3			216.8			(446.4		)	235
	Income taxes	—			—			(2.6		)	—			(2.6		)
	Net income	232.3			232.3			214.2			(446.4		)	232.4
	Less: Net income attributable to noncontrolling	—			—			0.1			—			0.1
	interests
	Net income attributable to ONEOK Partners, L.P.	$	232.3		$	232.3		$	214.1		$	(446.4	)	$	232.3
		Nine Months Ended September 30, 2013
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
	(Millions of dollars)
Revenues	$	—		$	—		$	8,420.40		$	—		$	8,420.40
Cost of sales and fuel	—			—			7,214.30			—			7,214.30
Net margin	—			—			1,206.10			—			1,206.10
Operating expenses
Operations and maintenance	—			—			338.4			—			338.4
Depreciation and amortization	—			—			174.1			—			174.1
General taxes	—			—			46.2			—			46.2
Total operating expenses	—			—			558.7			—			558.7
Gain on sale of assets	—			—			0.4			—			0.4
Operating income	—			—			647.8			—			647.8
Equity earnings from investments	575.3			575.3			31.6			(1,102.5		)	79.7
Allowance for equity funds used during	—			—			21.2			—			21.2
construction
Other income (expense), net	205.1			205.1			5.8			(410.2		)	5.8
Interest expense	(205.1		)	(205.1		)	(171.1		)	410.2			(171.1		)
Income before income taxes	575.3			575.3			535.3			(1,102.5		)	583.4
Income taxes	—			—			(7.9		)	—			(7.9		)
Net income	575.3			575.3			527.4			(1,102.5		)	575.5
Less: Net income attributable to noncontrolling	—			—			0.2			—			0.2
interests
Net income attributable to ONEOK Partners, L.P.	$	575.3		$	575.3		$	527.2		$	(1,102.5	)	$	575.3
	Nine Months Ended September 30, 2012
(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
				Subsidiary			Non-Guarantor			Entries
							Subsidiaries
	(Millions of dollars)
Revenues	$	—		$	—		$	7,266.40		$	—		$	7,266.40
Cost of sales and fuel	—			—			6,024.10			—			6,024.10
Net margin	—			—			1,242.30			—			1,242.30
Operating expenses
Operations and maintenance	—			—			319.9			—			319.9
Depreciation and amortization	—			—			150			—			150
General taxes	—			—			40.5			—			40.5
Total operating expenses	—			—			510.4			—			510.4
Gain on sale of assets	—			—			0.6			—			0.6
Operating income	—			—			732.5			—			732.5
Equity earnings from investments	677.6			677.6			37.9			(1,300.7		)	92.4
Allowance for equity funds used during	—			—			6.1			—			6.1
construction
Other income (expense), net	143.2			143.2			4.4			(286.4		)	4.4
Interest expense	(143.2		)	(143.2		)	(148.1		)	286.4			(148.1		)
Income before income taxes	677.6			677.6			632.8			(1,300.7		)	687.3
Income taxes	—			—			(9.4		)	—			(9.4		)
Net income	677.6			677.6			623.4			(1,300.7		)	677.9
Less: Net income attributable to noncontrolling	—			—			0.3			—			0.3
interests
Net income attributable to ONEOK Partners, L.P.	$	677.6		$	677.6		$	623.1		$	(1,300.7	)	$	677.6
Condensed Consolidating Statements of Comprehensive Income
	Three Months Ended September 30, 2013
(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
				Subsidiary			Non-Guarantor			Entries
							Subsidiaries
	(Millions of dollars)
Net income	$	216.3		$	216.3		$	199.9		$	(416.1	)	$	216.4
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives	(3.6		)	(10.3		)	(10.3		)	20.6			(3.6		)
Realized (gains) losses on derivatives recognized in	2.2			(0.4		)	(0.4		)	0.8			2.2
net income
Total other comprehensive income (loss)	(1.4		)	(10.7		)	(10.7		)	21.4			(1.4		)
Comprehensive income	214.9			205.6			189.2			(394.7		)	215
Less: Comprehensive income attributable to	—			—			0.1			—			0.1
noncontrolling interests
Comprehensive income attributable to	$	214.9		$	205.6		$	189.1		$	(394.7	)	$	214.9
ONEOK Partners, L.P.
	Three Months Ended September 30, 2012
(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
				Subsidiary			Non-Guarantor			Entries
							Subsidiaries
	(Millions of dollars)
Net income	$	232.3		$	232.3		$	214.2		$	(446.4	)	$	232.4
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives	(19.4		)	(18.2		)	(18.2		)	36.4			(19.4		)
Realized (gains) losses on derivatives recognized in	(19.8		)	(20.5		)	(20.5		)	41			(19.8		)
net income
Total other comprehensive income (loss)	(39.2		)	(38.7		)	(38.7		)	77.4			(39.2		)
Comprehensive income	193.1			193.6			175.5			(369.0		)	193.2
Less: Comprehensive income attributable to	—			—			0.1			—			0.1
noncontrolling interests
Comprehensive income attributable to	$	193.1		$	193.6		$	175.4		$	(369.0	)	$	193.1
ONEOK Partners, L.P.
	Nine Months Ended September 30, 2013
(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
				Subsidiary			Non-Guarantor			Entries
							Subsidiaries
	(Millions of dollars)
Net income	$	575.3		$	575.3		$	527.4		$	(1,102.5	)	$	575.5
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives	38.8			3.1			3.1			(6.2		)	38.8
Realized (gains) losses on derivatives recognized in	3.2			(4.2		)	(4.2		)	8.4			3.2
net income
Total other comprehensive income (loss)	42			(1.1		)	(1.1		)	2.2			42
Comprehensive income	617.3			574.2			526.3			(1,100.3		)	617.5
Less: Comprehensive income attributable to	—			—			0.2			—			0.2
noncontrolling interests
Comprehensive income attributable to	$	617.3		$	574.2		$	526.1		$	(1,100.3	)	$	617.3
ONEOK Partners, L.P.
	Nine Months Ended September 30, 2012
(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
				Subsidiary			Non-Guarantor			Entries
							Subsidiaries
	(Millions of dollars)
Net income	$	677.6		$	677.6		$	623.4		$	(1,300.7	)	$	677.9
Other comprehensive income (loss)
Unrealized gains (losses) on derivatives	1.6			41.5			41.5			(83.0		)	1.6
Realized (gains) losses on derivatives recognized in	(42.6		)	(43.5		)	(43.5		)	87			(42.6		)
net income
Total other comprehensive income (loss)	(41.0		)	(2.0		)	(2.0		)	4			(41.0		)
Comprehensive income	636.6			675.6			621.4			(1,296.7		)	636.9
Less: Comprehensive income attributable to	—			—			0.3			—			0.3
noncontrolling interests
Comprehensive income attributable to	$	636.6		$	675.6		$	621.1		$	(1,296.7	)	$	636.6
ONEOK Partners, L.P.
Condensed Consolidating Balance Sheets
	September 30, 2013
(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
				Subsidiary			Non-Guarantor			Entries
							Subsidiaries
Assets	(Millions of dollars)
Current assets
Cash and cash equivalents	$	—		$	723		$	—		$	—		$	723
Accounts receivable, net	—			—			956.6			—			956.6
Affiliate receivables	—			—			13.2			—			13.2
Gas and natural gas liquids in storage	—			—			390.6			—			390.6
Commodity imbalances	—			—			93.7			—			93.7
Other current assets	—			—			83.9			—			83.9
Total current assets	—			723			1,538.00			—			2,261.00
Property, plant and equipment
Property, plant and equipment	—			—			10,245.40			—			10,245.40
Accumulated depreciation and amortization	—			—			1,595.80			—			1,595.80
Net property, plant and equipment	—			—			8,649.60			—			8,649.60
Investments and other assets
Investments in unconsolidated affiliates	4,362.90			4,367.90			826.4			(8,355.3		)	1,201.90
Intercompany notes receivable	6,662.10			5,934.10			—			(12,596.2		)	—
Goodwill and intangible assets	—			—			640.1			—			640.1
Other assets	82.8			—			27.9			—			110.7
Total investments and other assets	11,107.80			10,302.00			1,494.40			(20,951.5		)	1,952.70
Total assets	$	11,107.80		$	11,025.00		$	11,682.00		$	(20,951.5	)	$	12,863.30
Liabilities and equity
Current liabilities
Current maturities of long-term debt	$	—		$	—		$	7.7		$	—		$	7.7
Notes payable	47			—			—			—			47
Accounts payable	—			—			1,202.00			—			1,202.00
Affiliate payables	—			—			43.9			—			43.9
Commodity imbalances	—			—			228.2			—			228.2
Accrued interest	88.5			—			—			—			88.5
Other current liabilities	—			—			99.6			—			99.6
Total current liabilities	135.5			—			1,581.40			—			1,716.90
Intercompany debt	—			6,662.10			5,934.10			(12,596.2		)	—
Long-term debt, excluding current maturities	5,985.00			—			61.5			—			6,046.50
Deferred credits and other liabilities	—			—			108			—			108
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in	4,987.30			4,362.90			3,992.40			(8,355.3		)	4,987.30
consolidated subsidiaries
Noncontrolling interests in consolidated	—			—			4.6			—			4.6
subsidiaries
Total equity	4,987.30			4,362.90			3,997.00			(8,355.3		)	4,991.90
Total liabilities and equity	$	11,107.80		$	11,025.00		$	11,682.00		$	(20,951.5	)	$	12,863.30
	December 31, 2012
(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
				Subsidiary			Non-Guarantor			Entries
							Subsidiaries
Assets	(Millions of dollars)
Current assets
Cash and cash equivalents	$	—		$	537.1		$	—		$	—		$	537.1
Accounts receivable, net	—			—			914			—			914
Affiliate receivables	—			—			16.1			—			16.1
Gas and natural gas liquids in storage	—			—			235.8			—			235.8
Commodity imbalances	—			—			89.7			—			89.7
Other current assets	10.9			—			88.1			—			99
Total current assets	10.9			537.1			1,343.70			—			1,891.70
Property, plant and equipment
Property, plant and equipment	—			—			8,585.20			—			8,585.20
Accumulated depreciation and amortization	—			—			1,440.90			—			1,440.90
Net property, plant and equipment	—			—			7,144.30			—			7,144.30
Investments and other assets
Investments in unconsolidated affiliates	4,458.70			3,858.90			828.6			(7,924.8		)	1,221.40
Intercompany notes receivable	4,770.60			4,833.30			—			(9,603.9		)	—
Goodwill and intangible assets	—			—			645.8			—			645.8
Other assets	31.6			—			24.4			—			56
Total investments and other assets	9,260.90			8,692.20			1,498.80			(17,528.7		)	1,923.20
Total assets	$	9,271.80		$	9,229.30		$	9,986.80		$	(17,528.7	)	$	10,959.20
Liabilities and equity
Current liabilities
Current maturities of long-term debt	$	—		$	—		$	7.6		$	—		$	7.6
Accounts payable	—			—			1,058.00			—			1,058.00
Affiliate payables	—			—			75.7			—			75.7
Commodity imbalances	—			—			273.2			—			273.2
Accrued interest	76.7			—			—			—			76.7
Other current liabilities	—			—			79.2			—			79.2
Total current liabilities	76.7			—			1,493.70			—			1,570.40
Intercompany debt	—			4,770.60			4,833.30			(9,603.9		)	—
Long-term debt, excluding current maturities	4,736.40			—			67.2			—			4,803.60
Deferred credits and other liabilities	—			—			121.7			—			121.7
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in	4,458.70			4,458.70			3,466.10			(7,924.8		)	4,458.70
consolidated subsidiaries
Noncontrolling interests in consolidated	—			—			4.8			—			4.8
subsidiaries
Total equity	4,458.70			4,458.70			3,470.90			(7,924.8		)	4,463.50
Total liabilities and equity	$	9,271.80		$	9,229.30		$	9,986.80		$	(17,528.7	)	$	10,959.20
Condensed Consolidating Statements of Cash Flows
	Nine Months Ended September 30, 2013
(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
				Subsidiary			Non-Guarantor			Entries
							Subsidiaries
	(Millions of dollars)
Operating activities
Cash provided by operating activities	$	641.5		$	48.1		$	634.5		$	(670.0	)	$	654.1
Investing activities
Capital expenditures (less allowance for equity	—			—			(1,373.9		)	—			(1,373.9		)
funds used during construction)
Acquisition	—			—			(304.9		)	—			(304.9		)
Contributions to unconsolidated affiliates	—			—			(4.6		)	—			(4.6		)
Distributions received from unconsolidated	—			17.3			7.6			—			24.9
affiliates
Proceeds from sale of assets	—			—			0.7			—			0.7
Cash provided by (used in) investing activities	—			17.3			(1,675.1		)	—			(1,657.8		)
Financing activities
Cash distributions:
General and limited partners	(670.0		)	(670.0		)	—			670			(670.0		)
Noncontrolling interests	—			—			(0.4		)	—			(0.4		)
Borrowing of notes payable, net	47			—			—			—			47
Issuance of long-term debt, net of discounts	1,247.80			—			—			—			1,247.80
Long-term debt financing costs	(10.2		)	—			—			—			(10.2		)
Intercompany borrowings (advances), net	(1,837.2		)	790.5			1,046.70			—			—
Repayment of long-term debt	—			—			(5.7		)	—			(5.7		)
Issuance of common units, net of issuance costs	569.2			—			—			—			569.2
Contribution from general partner	11.9			—			—			—			11.9
Cash provided by (used in) financing activities	(641.5		)	120.5			1,040.60			670			1,189.60
Change in cash and cash equivalents	—			185.9			—			—			185.9
Cash and cash equivalents at beginning of	—			537.1			—			—			537.1
period
Cash and cash equivalents at end of period	$	—		$	723		$	—		$	—		$	723
	Nine Months Ended September 30, 2012
(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
				Subsidiary			Non-Guarantor			Entries
							Subsidiaries
	(Millions of dollars)
Operating activities
Cash provided by operating activities	$	551		$	54.5		$	566		$	(551.0	)	$	620.5
Investing activities
Capital expenditures (less allowance for equity	—			—			(1,011.5		)	—			(1,011.5		)
funds used during construction)
Contributions to unconsolidated affiliates	—			—			(21.3		)	—			(21.3		)
Distributions received from unconsolidated	—			16.8			8.9			—			25.7
affiliates
Proceeds from sale of assets	—			—			1.7			—			1.7
Cash provided by (used in) investing activities	—			16.8			(1,022.2		)	—			(1,005.4		)
Financing activities
Cash distributions:
General and limited partners	(551.0		)	(551.0		)	—			551			(551.0		)
Noncontrolling interests	—			—			(0.6		)	—			(0.6		)
Issuance of long-term debt, net of discounts	1,295.00			—			—			—			1,295.00
Long-term debt financing costs	(9.7		)	—			—			—			(9.7		)
Intercompany borrowings (advances), net	(1,873.9		)	1,408.20			465.7			—			—
Repayment of long-term debt	(350.0		)	—			(8.9		)	—			(358.9		)
Issuance of common units, net of issuance costs	919.5			—			—			—			919.5
Contribution from general partner	19.1			—			—			—			19.1
Cash provided by (used in) financing activities	(551.0		)	857.2			456.2			551			1,313.40
Change in cash and cash equivalents	—			928.5			—			—			928.5
Cash and cash equivalents at beginning of	—			35.1			—			—			35.1
period
Cash and cash equivalents at end of period	$	—		$	963.6		$	—		$	—		$	963.6

SUMMARY_OF_SIGNIFICANT_ACCOUNT1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2013
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
Basis of Accounting, Policy [Policy Text Block]	'
	Our accompanying unaudited consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC.  These statements have been prepared in accordance with GAAP and reflect all adjustments that, in our opinion, are necessary for a fair presentation of the results for the interim periods presented.  All such adjustments are of a normal recurring nature.  The 2012 year-end consolidated balance sheet data was derived from our audited financial statements but does not include all disclosures required by GAAP.  These unaudited consolidated financial statements should be read in conjunction with our audited consolidated financial statements in our Annual Report.
	Our significant accounting policies are consistent with those disclosed in Note A of the Notes to Consolidated Financial Statements in our Annual Report.
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]	'
	We assess our goodwill for impairment at least annually on July 1, unless events or changes in circumstances indicate an impairment may have occurred before that time. At July 1, 2013, we assessed qualitative factors to determine whether it was more likely than not that the fair value of each of our reporting units was less than its carrying amount. After assessing qualitative factors (including macroeconomic conditions, industry and market considerations, cost factors and overall financial performance), we determined that no further testing was necessary.
Accounting Standards Update 2013-10 [Member]	'
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
New Accounting Pronouncement or Change in Accounting Principle, Description	' In July 2013, the FASB issued ASU 2013-10, bInclusion of the Fed Funds Effective Swap Rate (or Overnight Index Swap Rate) as a Benchmark Interest Rate for Hedge Accounting Purposes,b which allows an entity to designate the Fed Funds Effective Swap rate (also known as the Overnight Index Swap rate, or OIS rate, in the United States) as a benchmark interest rate for hedge accounting purposes in addition to the interest rates on direct Treasury obligations of the United States government and the LIBOR. This guidance is effective prospectively for qualifying new or redesigned hedging relationships entered into on or after July 17, 2013. We adopted this guidance with our September 30, 2013, Quarterly Report, and it did not impact materially our financial position or results of operations. See Note D for additional disclosures.
Accounting Standards Update 2013-02 [Member]	'
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
New Accounting Pronouncement or Change in Accounting Principle, Description	'In February 2013, the FASB issued ASU 2013-02, bReporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income,b which requires presentation in a single location, either in a single note or parenthetically on the face of the financial statements, the effect of significant amounts reclassified from each component of accumulated other comprehensive income based on its source. This guidance is effective for our interim and annual periods beginning on January 1, 2013, and is applied prospectively. We adopted this guidance with our March 31, 2013, Quarterly Report, and it did not impact our financial position or results of operations. See Note H for additional disclosures.
Accounting Standards Update 2011-11 [Member]	'
New Accounting Pronouncements or Change in Accounting Principle [Line Items]	'
New Accounting Pronouncement or Change in Accounting Principle, Description	'In December 2011, the FASB issued ASU 2011-11, bDisclosures about Offsetting Assets and Liabilities,b which increases disclosures about offsetting assets and liabilities. In January 2013, the FASB issued ASU 2013-01, bClarifying the Scope of Disclosures about Offsetting Assets and Liabilities,b which clarifies that the scope of ASU 2011-11 applies to derivatives accounted for in accordance with Topic 815, Derivatives and Hedging. New disclosures are required to enable users of financial statements to understand significant quantitative differences in balance sheets prepared under GAAP and International Financial Reporting Standards related to the offsetting of financial instruments, including derivatives. The existing GAAP guidance allowing balance sheet offsetting remains unchanged. This guidance is effective for interim and annual periods beginning on January 1, 2013, and is applied retrospectively for all comparative periods presented. We adopted this guidance beginning with our March 31, 2013, Quarterly Report, and it did not impact our financial position or results of operations. See Note C for additional disclosures.

ACQUISITION_Policies

ACQUISITION (Policies)	9 Months Ended
	Sep. 30, 2013
Acquisition [Abstract]	'
Business Combinations Policy [Policy Text Block]	'
	We accounted for this transaction using the acquisition method of accounting, which requires, among other things, that the assets acquired and liabilities assumed be recognized on the balance sheet at their fair values as of the acquisition date. We are developing a preliminary purchase price allocation, which will be adjusted as additional information relative to the fair value of assets and liabilities, which could include intangible assets and goodwill, becomes available. As we have not completed the purchase price allocation for this transaction, we have recorded the purchase price in property, plant and equipment in our consolidated balance sheet at September 30, 2013.

RISK_MANAGEMENT_AND_HEDGING_AC1

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES (Policies)	9 Months Ended
	Sep. 30, 2013
RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES [Abstract]	'
Accounting treatment for derivative instruments	'
	Accounting Treatment - We record all derivative instruments at fair value, with the exception of normal purchases and normal sales that are expected to result in physical delivery.  The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and, if so, the reason for holding it.
	The table below summarizes the various ways in which we account for our derivative instruments and the impact on our consolidated financial statements:
			Recognition and Measurement
	Accounting Treatment		Balance Sheet		Income Statement
	Normal purchases and normal sales	-	Fair value not recorded	-	Change in fair value not recognized in earnings
	Mark-to-market	-	Recorded at fair value	-	Change in fair value recognized in earnings
	Cash flow hedge	-	Recorded at fair value	-	Ineffective portion of the gain or loss on the
					derivative instrument is recognized in earnings
		-	Effective portion of the gain or loss on the	-	Effective portion of the gain or loss on the
			derivative instrument is reported initially		derivative instrument is reclassified out of
			as a 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
	Under certain conditions, we designate our derivative instruments as a hedge of exposure to changes in fair values or cash flows.  We formally document all relationships between hedging instruments and hedged items, as well as risk-management objectives, 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 with a cash flow hedge.  We assess the effectiveness of hedging relationships quarterly by performing an effectiveness analysis on our fair value and cash flow hedging relationships to determine whether the hedge relationships are highly effective on a retrospective and prospective basis.  We also document our normal purchases and normal sales transactions that we expect to result in physical delivery and that we elect to exempt from derivative accounting treatment.
	The realized revenues and purchase costs of our derivative instruments not considered held for trading purposes and derivatives that qualify as normal purchases or normal sales that are expected to result in physical delivery are reported on a gross basis.
	Cash flows from futures, forwards and swaps that are accounted for as hedges are included in the same category as the cash flows from the related hedged items in our Consolidated Statements of Cash Flows.

EQUITY_Policies

EQUITY (Policies)	9 Months Ended
	Sep. 30, 2013
EQUITY (Policies)	'
Partnership agreement	'
	Partnership Agreement - Available cash, as defined in our Partnership Agreement, generally will be distributed to our general partner and limited partners according to their partnership percentages of 2 percent and 98 percent, respectively. Our general partner’s percentage interest in quarterly distributions is increased after certain specified target levels are met during the quarter. Under the incentive distribution provisions, as set forth in our Partnership Agreement, our general partner receives:
	•	15 percent of amounts distributed in excess of $0.3025 per unit;
	•	25 percent of amounts distributed in excess of $0.3575 per unit; and
	•	50 percent of amounts distributed in excess of $0.4675 per unit.

SEGMENTS_Policies

SEGMENTS (Policies)	9 Months Ended
	Sep. 30, 2013
Segment Accounting Policies [Abstract]	'
Segment Accounting Policies [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 of the Notes to Consolidated Financial Statements in our Annual Report.  Intersegment and affiliate sales are recorded on the same basis as sales to unaffiliated customers.  Net margin is comprised of total revenues less cost of sales and fuel.  Cost of sales and fuel includes commodity purchases, fuel and transportation costs.

FAIR_VALUE_MEASUREMENTS_Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2013
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:
		September 30, 2013
		Level 1			Level 2			Level 3			Total - Gross			Netting (a)			Total - Net (b)
		(Thousands of dollars)
	Derivatives assets
	Commodity contracts
	Financial contracts	$	—		$	15,656		$	5,148		$	20,804		$	(4,436	)	$	16,368
	Physical contracts	—			—			351			351			—			351
	Interest-rate contracts	—			43,614			—			43,614			—			43,614
	Total derivative assets	$	—		$	59,270		$	5,499		$	64,769		$	(4,436	)	$	60,333
	Derivatives liabilities
	Commodity contracts
	Financial contracts	$	—		$	(2,150	)	$	(2,286	)	$	(4,436	)	$	4,436		$	—
	Physical contracts	—			—			(2,712		)	(2,712		)	—			(2,712		)
	Total derivative liabilities	$	—		$	(2,150	)	$	(4,998	)	$	(7,148	)	$	4,436		$	(2,712	)
		December 31, 2012
		Level 1			Level 2			Level 3			Total - Gross			Netting (a)			Total - Net (b)
		(Thousands of dollars)
	Derivatives assets
	Commodity contracts - financial	$	—		$	17,581		$	1		$	17,582		$	(2,455	)	$	15,127
	Interest-rate contracts	—			10,923			—			10,923			—			10,923
	Total derivative assets	$	—		$	28,504		$	1		$	28,505		$	(2,455	)	$	26,050
	Derivatives liabilities
	Commodity contracts - financial	$	—		$	(31	)	$	(2,424	)	$	(2,455	)	$	2,455		$	—
	Total derivative liabilities	$	—		$	(31	)	$	(2,424	)	$	(2,455	)	$	2,455		$	—
	(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.
	(b) - Included in other current assets, other assets or other current liabilities in our Consolidated Balance Sheets.
Reconciliation of Level 3 Fair Value Measurements	'
	The following table sets forth a reconciliation of our Level 3 fair value measurements for the periods indicated:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	Derivative Assets (Liabilities)	2013			2012			2013			2012
		(Thousands of dollars)
	Net assets (liabilities) at beginning of period	$	7,682		$	29,862		$	(2,423	)	$	3,117
	Total realized/unrealized gains (losses) included in other	(7,181		)	(19,959		)	2,924			6,786
	comprehensive income (loss)
	Net assets at end of period	$	501		$	9,903		$	501		$	9,903

RISK_MANAGEMENT_AND_HEDGING_AC2

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES (Tables)	9 Months Ended
	Sep. 30, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of Derivative Instruments in Statement of Financial Position	'
	Fair Values of Derivative Instruments - See Note C for a discussion of the inputs associated with our fair value measurements. The following table sets forth the fair values of our derivative instruments, all of which were designated as cash flow hedges for the periods indicated:
		September 30, 2013								December 31, 2012
		Assets (a)				(Liabilities) (a)				Assets (b)				(Liabilities) (b)
		(Thousands of dollars)
	Commodity contracts - financial	$	20,804			$	(4,436	)		$	17,582			$	(2,455	)
	Commodity contracts - physical	351				(2,712		)		—				—
	Interest-rate contracts	43,614				—				10,923				—
	Total derivatives designated as hedging instruments	$	64,769			$	(7,148	)		$	28,505			$	(2,455	)
	(a) - Included on a net basis in other current assets, other assets or other current liabilities on our Consolidated Balance Sheets.
	(b) - Included on a net basis in other current assets or other assets 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 designated as hedging instruments for the periods indicated:
			30-Sep-13								December 31, 2012
		Contract	Purchased/				Sold/				Purchased/				Sold/
		Type	Payor				Receiver				Payor				Receiver
	Cash flow hedges
	Fixed price
	- Natural gas (Bcf)	Swaps	—				(49.4		)		—				(31.7		)
	- Crude oil and NGLs (MMbbl)	Forwards and swaps	—				(2.3		)		—				(1.1		)
	Basis
	- Natural gas (Bcf)	Swaps	—				(49.4		)		—				(31.7		)
	Interest-rate contracts (Millions of dollars)	Forward-starting	$	400			$	—			$	400			$	—
		swaps
Schedule of Cash Flow Hedges in Other Comprehensive Income (Loss)	'
	The following table sets forth the effect of cash flow hedges recognized in other comprehensive income (loss) for the periods indicated:
		Three Months Ended								Nine Months Ended
	Derivatives in Cash Flow	September 30,								September 30,
	Hedging Relationships	2013				2012				2013				2012
		(Thousands of dollars)
	Commodity contracts	$	(10,317	)		$	(18,186	)		$	3,060			$	41,469
	Interest-rate contracts	6,721				(1,175		)		35,726				(39,832		)
	Total unrealized gain (loss) recognized in other comprehensive	$	(3,596	)		$	(19,361	)		$	38,786			$	1,637
	loss (effective portion)
Schedule of Derivative Instruments, Gain (loss) of Statement of Financial Performance	'
	The following table sets forth the effect of cash flow hedges in our Consolidated Statements of Income for the periods indicated:
	Derivatives in Cash Flow	Location of Gain (Loss) Reclassified from	Three Months Ended								Nine Months Ended
	Hedging Relationships	Accumulated Other Comprehensive Income	September 30,								September 30,
		(Loss) into Net Income (Effective Portion)	2013				2012				2013				2012
			(Thousands of dollars)
	Commodity contracts	Revenues	$	361			$	20,549			$	4,172			$	43,527
	Interest-rate contracts	Interest expense	(2,565		)		(697		)		(7,445		)		(880		)
	Total gain (loss) reclassified from accumulated other comprehensive loss		$	(2,204	)		$	19,852			$	(3,273	)		$	42,647
	into net income (effective portion)

EQUITY_Tables

EQUITY (Tables)	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Schedule of distributions made to general or limited partner	'
	The following table shows our distributions paid in the periods indicated:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(Thousands, except per unit amounts)
	Distribution per unit	$	0.72	$	0.66	$	2.145	$	1.905
	General partner distributions	$	4,512	$	3,979	$	13,399	$	11,019
	Incentive distributions	62,634		49,886		184,647		130,968
	Distributions to general partner	67,146		53,865		198,046		141,987
	Limited partner distributions to ONEOK	66,807		61,240		199,031		171,882
	Limited partner distributions to other unitholders	91,676		83,838		272,904		237,109
	Total distributions paid	$	225,629	$	198,943	$	669,981	$	550,978
Schedule of distributions declared to general or limited partner	'
	The following table shows our distributions declared for the periods indicated and paid within 45 days of the end of the period:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(Thousands, except per unit amounts)
	Distribution per unit	$	0.725	$	0.685	$	2.16	$	1.98
	General partner distributions	$	4,795	$	4,199	$	13,776	$	11,937
	Incentive distributions	67,017		55,162		191,226		149,658
	Distributions to general partner	71,812		59,361		205,002		161,595
	Limited partner distributions to ONEOK	67,271		63,560		200,422		183,721
	Limited partner distributions to other unitholders	100,650		87,014		283,365		251,514
	Total distributions declared	$	239,733	$	209,935	$	688,789	$	596,830

ACCUMULATED_OTHER_COMPREHENSIV1

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	9 Months Ended
	Sep. 30, 2013
Accumulated other comprehensive income (loss)	'
	The following table sets forth the balance in accumulated other comprehensive income (loss) for the period indicated:
			Accumulated
			Other
			Comprehensive
			Loss (a)
			(Thousands of dollars)
	1-Jan-13		$	(99,322	)
	Other comprehensive income (loss) before reclassifications		38,786
	Amounts reclassified from accumulated other comprehensive income (loss)		3,273
	Net current-period other comprehensive income (loss) attributable to ONEOK Partners		42,059
	30-Sep-13		$	(57,263	)
	(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		Three Months Ended			Nine Months Ended			Affected Line Item in the
		Comprehensive Income (Loss) Components		30-Sep-13			30-Sep-13			Consolidated Statements of Income
				(Thousand of dollars)
		Unrealized (gains) losses on risk-management
		assets/liabilities
		Commodity contracts		$	(361	)	$	(4,172	)	Revenues
		Interest-rate contracts		2,565			7,445			Interest expense
		Total reclassifications for the period		$	2,204		$	3,273		Net income attributable to ONEOK
		attributable to ONEOK Partners								Partners

UNCONSOLIDATED_AFFILIATES_Tabl

UNCONSOLIDATED AFFILIATES (Tables)	9 Months Ended
	Sep. 30, 2013
Equity Method Investments and Joint Ventures [Abstract]	'
Unconsolidated Affiliates Financial Information	'
	Equity Earnings from Investments - The following table sets forth our equity earnings from investments for the periods indicated:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(Thousands of dollars)
	Northern Border Pipeline	$	16,464	$	18,185	$	48,133	$	54,493
	Overland Pass Pipeline Company	5,783		4,490		14,210		15,786
	Fort Union Gas Gathering	2,946		4,091		9,895		11,494
	Bighorn Gas Gathering	559		1,157		1,897		3,118
	Other	1,716		668		5,609		7,489
	Equity earnings from investments	$	27,468	$	28,591	$	79,744	$	92,380
Unconsolidated Affiliates Financial Information [Table Text Block]	'
	Unconsolidated Affiliates Financial Information - The following table sets forth summarized combined financial information of our unconsolidated affiliates for the periods indicated:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(Thousands of dollars)
	Income Statement
	Operating revenues	$	131,959	$	125,828	$	391,912	$	373,038
	Operating expenses	$	63,971	$	60,937	$	189,366	$	173,232
	Net income	$	61,630	$	55,721	$	185,580	$	180,787
	Distributions paid to us	$	34,409	$	34,557	$	103,913	$	118,752

RELATEDPARTY_TRANSACTIONS_Tabl

RELATED-PARTY TRANSACTIONS (Tables)	9 Months Ended
	Sep. 30, 2013
Related Party Transactions [Abstract]	'
Schedule of Related Party Transactions [Table Text Block]	'
	The following table sets forth the transactions with related parties for the periods indicated:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(Thousands of dollars)
	Revenues	$	81,324	$	91,096	$	255,298	$	247,851
	Expenses
	Cost of sales and fuel	$	9,562	$	7,831	$	27,855	$	22,875
	Administrative and general expenses	58,549		60,020		192,906		179,017
	Total expenses	$	68,111	$	67,851	$	220,761	$	201,892

SEGMENTS_Tables

SEGMENTS (Tables)	9 Months Ended
	Sep. 30, 2013
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:
	Three Months Ended	Natural Gas		Natural Gas			Natural Gas			Other and			Total
	30-Sep-13	Gathering and		Liquids (a)			Pipelines (b)			Eliminations
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	162,677	$	2,840,108		$	50,624		$	—		$	3,053,409
	Sales to affiliated customers	57,400		—			23,924			—			81,324
	Intersegment revenues	312,940		34,740			1,330			(349,010		)	—
	Total revenues	$	533,017	$	2,874,848		$	75,878		$	(349,010	)	$	3,134,733
	Net margin	$	130,882	$	226,242		$	69,457		$	(3,007	)	$	423,574
	Operating costs	45,074		57,010			23,457			(3,179		)	122,362
	Depreciation and amortization	27,356		22,993			10,833			—			61,182
	Gain (loss) on sale of assets	31		7			(16		)	—			22
	Operating income	$	58,483	$	146,246		$	35,151		$	172		$	240,052
	Equity earnings from investments	$	4,668	$	6,336		$	16,464		$	—		$	27,468
	Capital expenditures	$	204,542	$	230,780		$	11,148		$	2,602		$	449,072
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $147.1 million, of which $130.2 million related to sales within the segment, net margin of $89.5 million and operating income of $53.4 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $57.5 million, net margin of $52.8 million and operating income of $22.6 million.
	Three Months Ended	Natural Gas		Natural Gas			Natural Gas			Other and			Total
	30-Sep-12	Gathering and		Liquids (a)			Pipelines (b)			Eliminations
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	114,127	$	2,287,191		$	55,046		$	—		$	2,456,364
	Sales to affiliated customers	67,269		—			23,827			—			91,096
	Intersegment revenues	197,733		23,777			910			(222,420		)	—
	Total revenues	$	379,129	$	2,310,968		$	79,783		$	(222,420	)	$	2,547,460
	Net margin	$	115,869	$	234,546		$	71,402		$	(2,080	)	$	419,737
	Operating costs	39,371		56,756			26,265			(1,216		)	121,176
	Depreciation and amortization	19,565		18,588			11,592			9			49,754
	Gain (loss) on sale of assets	25		(362		)	(83		)	—			(420		)
	Operating income	$	56,958	$	158,840		$	33,462		$	(873	)	$	248,387
	Equity earnings from investments	$	5,546	$	4,731		$	18,314		$	—		$	28,591
	Capital expenditures	$	157,714	$	212,331		$	5,119		$	127		$	375,291
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $119.2 million, of which $103.7 million related to sales within the segment, net margin of $68.0 million and operating income of $40.8 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $62.4 million, net margin of $54.9 million and operating income of $22.8 million.
	Nine Months Ended	Natural Gas		Natural Gas			Natural Gas			Other and			Total
	30-Sep-13	Gathering and		Liquids (a)			Pipelines (b)			Eliminations
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	466,631	$	7,539,470		$	158,960		$	—		$	8,165,061
	Sales to affiliated customers	179,636		—			75,662			—			255,298
	Intersegment revenues	806,523		91,161			2,327			(900,011		)	—
	Total revenues	$	1,452,790	$	7,630,631		$	236,949		$	(900,011	)	$	8,420,359
	Net margin	$	365,436	$	632,087		$	211,224		$	(2,621	)	$	1,206,126
	Operating costs	141,737		171,076			75,608			(3,819		)	384,602
	Depreciation and amortization	76,366		65,033			32,687			—			174,086
	Gain (loss) on sale of assets	344		10			(12		)	—			342
	Operating income	$	147,677	$	395,988		$	102,917		$	1,198		$	647,780
	Equity earnings from investments	$	16,228	$	15,383		$	48,133		$	—		$	79,744
	Investments in unconsolidated affiliates	$	331,124	$	494,702		$	376,047		$	—		$	1,201,873
	Total assets	$	3,808,135	$	6,610,205		$	1,786,413		$	658,573		$	12,863,326
	Noncontrolling interests in consolidated subsidiaries	$	4,574	$	—		$	—		$	14		$	4,588
	Capital expenditures	$	574,509	$	774,284		$	22,497		$	2,614		$	1,373,904
	(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $376.9 million, of which $321.3 million related to sales within the segment, net margin of $227.8 million and operating income of $129.0 million.
	(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $182.0 million, net margin of $162.5 million and operating income of $67.0 million.
	Nine Months Ended	Natural Gas		Natural Gas			Natural Gas			Other and			Total
	30-Sep-12	Gathering and		Liquids (a)			Pipelines (b)			Eliminations
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	307,145	$	6,554,291		$	157,067		$	—		$	7,018,503
	Sales to affiliated customers	177,213		—			70,638			—			247,851
	Intersegment revenues	588,379		55,902			2,788			(647,069		)	—
	Total revenues	$	1,072,737	$	6,610,193		$	230,493		$	(647,069	)	$	7,266,354
Net margin	$	332,305	$	703,657		$	212,002		$	(5,675	)	$	1,242,289
Operating costs	120,857		166,622			78,291			(5,360		)	360,410
Depreciation and amortization	61,335		54,155			34,525			9			150,024
Gain (loss) on sale of assets	1,154		(456		)	(95		)	—			603
Operating income	$	151,267	$	482,424		$	99,091		$	(324	)	$	732,458
Equity earnings from investments	$	21,031	$	16,378		$	54,971		$	—		$	92,380
Investments in unconsolidated affiliates	$	323,503	$	488,308		$	406,471		$	—		$	1,218,282
Total assets	$	2,797,692	$	5,169,516		$	1,855,209		$	970,176		$	10,792,593
Noncontrolling interests in consolidated subsidiaries	$	—	$	—		$	4,797		$	15		$	4,812
Capital expenditures	$	435,122	$	561,492		$	14,584		$	329		$	1,011,527
(a) - Our Natural Gas Liquids segment has regulated and nonregulated operations. Our Natural Gas Liquids segment’s regulated operations had revenues of $333.9 million, of which $285.8 million related to sales within the segment, net margin of $197.2 million and operating income of $115.5 million.
(b) - Our Natural Gas Pipelines segment has regulated and nonregulated operations. Our Natural Gas Pipelines segment’s regulated operations had revenues of $179.1 million, net margin of $162.5 million and operating income of $66.8 million.

SUPPLEMENTAL_CONDENSED_CONSOLI1

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2013
Condensed Financial Information of Parent Company Only Disclosure [Abstract]	'
Condensed Consolidating Statements of Income	'
	Condensed Consolidating Statements of Income
		Three Months Ended September 30, 2013
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Revenues	$	—		$	—		$	3,134.70		$	—		$	3,134.70
	Cost of sales and fuel	—			—			2,711.10			—			2,711.10
	Net margin	—			—			423.6			—			423.6
	Operating expenses
	Operations and maintenance	—			—			109			—			109
	Depreciation and amortization	—			—			61.2			—			61.2
	General taxes	—			—			13.3			—			13.3
	Total operating expenses	—			—			183.5			—			183.5
	Operating income	—			—			240.1			—			240.1
	Equity earnings from investments	216.3			216.3			11			(416.1		)	27.5
	Allowance for equity funds used during	—			—			6.4			—			6.4
	construction
	Other income (expense), net	70.6			70.6			3.1			(141.2		)	3.1
	Interest expense	(70.6		)	(70.6		)	(57.7		)	141.2			(57.7		)
	Income before income taxes	216.3			216.3			202.9			(416.1		)	219.4
	Income taxes	—			—			(3.0		)	—			(3.0		)
	Net income	216.3			216.3			199.9			(416.1		)	216.4
	Less: Net income attributable to noncontrolling	—			—			0.1			—			0.1
	interests
	Net income attributable to ONEOK Partners, L.P.	$	216.3		$	216.3		$	199.8		$	(416.1	)	$	216.3
		Three Months Ended September 30, 2012
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Revenues	$	—		$	—		$	2,547.50		$	—		$	2,547.50
	Cost of sales and fuel	—			—			2,127.80			—			2,127.80
	Net margin	—			—			419.7			—			419.7
	Operating expenses
	Operations and maintenance	—			—			110.3			—			110.3
	Depreciation and amortization	—			—			49.7			—			49.7
	General taxes	—			—			10.9			—			10.9
	Total operating expenses	—			—			170.9			—			170.9
	Loss on sale of assets	—			—			(0.4		)	—			(0.4		)
	Operating income	—			—			248.4			—			248.4
	Equity earnings from investments	232.3			232.3			10.4			(446.4		)	28.6
	Allowance for equity funds used during	—			—			3.3			—			3.3
	construction
	Other income (expense), net	46.2			46.2			2.5			(92.4		)	2.5
	Interest expense	(46.2		)	(46.2		)	(47.8		)	92.4			(47.8		)
	Income before income taxes	232.3			232.3			216.8			(446.4		)	235
	Income taxes	—			—			(2.6		)	—			(2.6		)
	Net income	232.3			232.3			214.2			(446.4		)	232.4
	Less: Net income attributable to noncontrolling	—			—			0.1			—			0.1
	interests
	Net income attributable to ONEOK Partners, L.P.	$	232.3		$	232.3		$	214.1		$	(446.4	)	$	232.3
		Nine Months Ended September 30, 2013
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Revenues	$	—		$	—		$	8,420.40		$	—		$	8,420.40
	Cost of sales and fuel	—			—			7,214.30			—			7,214.30
	Net margin	—			—			1,206.10			—			1,206.10
	Operating expenses
	Operations and maintenance	—			—			338.4			—			338.4
	Depreciation and amortization	—			—			174.1			—			174.1
General taxes	—			—			46.2			—			46.2
Total operating expenses	—			—			558.7			—			558.7
Gain on sale of assets	—			—			0.4			—			0.4
Operating income	—			—			647.8			—			647.8
Equity earnings from investments	575.3			575.3			31.6			(1,102.5		)	79.7
Allowance for equity funds used during	—			—			21.2			—			21.2
construction
Other income (expense), net	205.1			205.1			5.8			(410.2		)	5.8
Interest expense	(205.1		)	(205.1		)	(171.1		)	410.2			(171.1		)
Income before income taxes	575.3			575.3			535.3			(1,102.5		)	583.4
Income taxes	—			—			(7.9		)	—			(7.9		)
Net income	575.3			575.3			527.4			(1,102.5		)	575.5
Less: Net income attributable to noncontrolling	—			—			0.2			—			0.2
interests
Net income attributable to ONEOK Partners, L.P.	$	575.3		$	575.3		$	527.2		$	(1,102.5	)	$	575.3
	Nine Months Ended September 30, 2012
(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
				Subsidiary			Non-Guarantor			Entries
							Subsidiaries
	(Millions of dollars)
Revenues	$	—		$	—		$	7,266.40		$	—		$	7,266.40
Cost of sales and fuel	—			—			6,024.10			—			6,024.10
Net margin	—			—			1,242.30			—			1,242.30
Operating expenses
Operations and maintenance	—			—			319.9			—			319.9
Depreciation and amortization	—			—			150			—			150
General taxes	—			—			40.5			—			40.5
Total operating expenses	—			—			510.4			—			510.4
Gain on sale of assets	—			—			0.6			—			0.6
Operating income	—			—			732.5			—			732.5
Equity earnings from investments	677.6			677.6			37.9			(1,300.7		)	92.4
Allowance for equity funds used during	—			—			6.1			—			6.1
construction
Other income (expense), net	143.2			143.2			4.4			(286.4		)	4.4
Interest expense	(143.2		)	(143.2		)	(148.1		)	286.4			(148.1		)
Income before income taxes	677.6			677.6			632.8			(1,300.7		)	687.3
Income taxes	—			—			(9.4		)	—			(9.4		)
Net income	677.6			677.6			623.4			(1,300.7		)	677.9
Less: Net income attributable to noncontrolling	—			—			0.3			—			0.3
interests
Net income attributable to ONEOK Partners, L.P.	$	677.6		$	677.6		$	623.1		$	(1,300.7	)	$	677.6
Condensed Consolidating Statements of Comprehensive Income	'
	Condensed Consolidating Statements of Comprehensive Income
		Three Months Ended September 30, 2013
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Net income	$	216.3		$	216.3		$	199.9		$	(416.1	)	$	216.4
	Other comprehensive income (loss)
	Unrealized gains (losses) on derivatives	(3.6		)	(10.3		)	(10.3		)	20.6			(3.6		)
	Realized (gains) losses on derivatives recognized in	2.2			(0.4		)	(0.4		)	0.8			2.2
	net income
	Total other comprehensive income (loss)	(1.4		)	(10.7		)	(10.7		)	21.4			(1.4		)
	Comprehensive income	214.9			205.6			189.2			(394.7		)	215
	Less: Comprehensive income attributable to	—			—			0.1			—			0.1
	noncontrolling interests
	Comprehensive income attributable to	$	214.9		$	205.6		$	189.1		$	(394.7	)	$	214.9
	ONEOK Partners, L.P.
		Three Months Ended September 30, 2012
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Net income	$	232.3		$	232.3		$	214.2		$	(446.4	)	$	232.4
	Other comprehensive income (loss)
	Unrealized gains (losses) on derivatives	(19.4		)	(18.2		)	(18.2		)	36.4			(19.4		)
	Realized (gains) losses on derivatives recognized in	(19.8		)	(20.5		)	(20.5		)	41			(19.8		)
	net income
	Total other comprehensive income (loss)	(39.2		)	(38.7		)	(38.7		)	77.4			(39.2		)
	Comprehensive income	193.1			193.6			175.5			(369.0		)	193.2
	Less: Comprehensive income attributable to	—			—			0.1			—			0.1
	noncontrolling interests
	Comprehensive income attributable to	$	193.1		$	193.6		$	175.4		$	(369.0	)	$	193.1
	ONEOK Partners, L.P.
		Nine Months Ended September 30, 2013
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Net income	$	575.3		$	575.3		$	527.4		$	(1,102.5	)	$	575.5
	Other comprehensive income (loss)
	Unrealized gains (losses) on derivatives	38.8			3.1			3.1			(6.2		)	38.8
	Realized (gains) losses on derivatives recognized in	3.2			(4.2		)	(4.2		)	8.4			3.2
	net income
	Total other comprehensive income (loss)	42			(1.1		)	(1.1		)	2.2			42
	Comprehensive income	617.3			574.2			526.3			(1,100.3		)	617.5
	Less: Comprehensive income attributable to	—			—			0.2			—			0.2
	noncontrolling interests
	Comprehensive income attributable to	$	617.3		$	574.2		$	526.1		$	(1,100.3	)	$	617.3
	ONEOK Partners, L.P.
		Nine Months Ended September 30, 2012
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Net income	$	677.6		$	677.6		$	623.4		$	(1,300.7	)	$	677.9
	Other comprehensive income (loss)
	Unrealized gains (losses) on derivatives	1.6			41.5			41.5			(83.0		)	1.6
	Realized (gains) losses on derivatives recognized in	(42.6		)	(43.5		)	(43.5		)	87			(42.6		)
	net income
	Total other comprehensive income (loss)	(41.0		)	(2.0		)	(2.0		)	4			(41.0		)
	Comprehensive income	636.6			675.6			621.4			(1,296.7		)	636.9
	Less: Comprehensive income attributable to	—			—			0.3			—			0.3
	noncontrolling interests
Comprehensive income attributable to	$	636.6		$	675.6		$	621.1		$	(1,296.7	)	$	636.6
ONEOK Partners, L.P.
Condensed Consolidating Balance Sheets	'
	Condensed Consolidating Balance Sheets
		September 30, 2013
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
	Assets	(Millions of dollars)
	Current assets
	Cash and cash equivalents	$	—		$	723		$	—		$	—		$	723
	Accounts receivable, net	—			—			956.6			—			956.6
	Affiliate receivables	—			—			13.2			—			13.2
	Gas and natural gas liquids in storage	—			—			390.6			—			390.6
	Commodity imbalances	—			—			93.7			—			93.7
	Other current assets	—			—			83.9			—			83.9
	Total current assets	—			723			1,538.00			—			2,261.00
	Property, plant and equipment
	Property, plant and equipment	—			—			10,245.40			—			10,245.40
	Accumulated depreciation and amortization	—			—			1,595.80			—			1,595.80
	Net property, plant and equipment	—			—			8,649.60			—			8,649.60
	Investments and other assets
	Investments in unconsolidated affiliates	4,362.90			4,367.90			826.4			(8,355.3		)	1,201.90
	Intercompany notes receivable	6,662.10			5,934.10			—			(12,596.2		)	—
	Goodwill and intangible assets	—			—			640.1			—			640.1
	Other assets	82.8			—			27.9			—			110.7
	Total investments and other assets	11,107.80			10,302.00			1,494.40			(20,951.5		)	1,952.70
	Total assets	$	11,107.80		$	11,025.00		$	11,682.00		$	(20,951.5	)	$	12,863.30
	Liabilities and equity
	Current liabilities
	Current maturities of long-term debt	$	—		$	—		$	7.7		$	—		$	7.7
	Notes payable	47			—			—			—			47
	Accounts payable	—			—			1,202.00			—			1,202.00
	Affiliate payables	—			—			43.9			—			43.9
	Commodity imbalances	—			—			228.2			—			228.2
	Accrued interest	88.5			—			—			—			88.5
	Other current liabilities	—			—			99.6			—			99.6
	Total current liabilities	135.5			—			1,581.40			—			1,716.90
	Intercompany debt	—			6,662.10			5,934.10			(12,596.2		)	—
	Long-term debt, excluding current maturities	5,985.00			—			61.5			—			6,046.50
	Deferred credits and other liabilities	—			—			108			—			108
	Commitments and contingencies
	Equity
	Equity excluding noncontrolling interests in	4,987.30			4,362.90			3,992.40			(8,355.3		)	4,987.30
	consolidated subsidiaries
	Noncontrolling interests in consolidated	—			—			4.6			—			4.6
	subsidiaries
	Total equity	4,987.30			4,362.90			3,997.00			(8,355.3		)	4,991.90
	Total liabilities and equity	$	11,107.80		$	11,025.00		$	11,682.00		$	(20,951.5	)	$	12,863.30
		December 31, 2012
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
	Assets	(Millions of dollars)
	Current assets
	Cash and cash equivalents	$	—		$	537.1		$	—		$	—		$	537.1
	Accounts receivable, net	—			—			914			—			914
	Affiliate receivables	—			—			16.1			—			16.1
	Gas and natural gas liquids in storage	—			—			235.8			—			235.8
	Commodity imbalances	—			—			89.7			—			89.7
	Other current assets	10.9			—			88.1			—			99
	Total current assets	10.9			537.1			1,343.70			—			1,891.70
	Property, plant and equipment
	Property, plant and equipment	—			—			8,585.20			—			8,585.20
	Accumulated depreciation and amortization	—			—			1,440.90			—			1,440.90
	Net property, plant and equipment	—			—			7,144.30			—			7,144.30
Investments and other assets
Investments in unconsolidated affiliates	4,458.70			3,858.90			828.6			(7,924.8		)	1,221.40
Intercompany notes receivable	4,770.60			4,833.30			—			(9,603.9		)	—
Goodwill and intangible assets	—			—			645.8			—			645.8
Other assets	31.6			—			24.4			—			56
Total investments and other assets	9,260.90			8,692.20			1,498.80			(17,528.7		)	1,923.20
Total assets	$	9,271.80		$	9,229.30		$	9,986.80		$	(17,528.7	)	$	10,959.20
Liabilities and equity
Current liabilities
Current maturities of long-term debt	$	—		$	—		$	7.6		$	—		$	7.6
Accounts payable	—			—			1,058.00			—			1,058.00
Affiliate payables	—			—			75.7			—			75.7
Commodity imbalances	—			—			273.2			—			273.2
Accrued interest	76.7			—			—			—			76.7
Other current liabilities	—			—			79.2			—			79.2
Total current liabilities	76.7			—			1,493.70			—			1,570.40
Intercompany debt	—			4,770.60			4,833.30			(9,603.9		)	—
Long-term debt, excluding current maturities	4,736.40			—			67.2			—			4,803.60
Deferred credits and other liabilities	—			—			121.7			—			121.7
Commitments and contingencies
Equity
Equity excluding noncontrolling interests in	4,458.70			4,458.70			3,466.10			(7,924.8		)	4,458.70
consolidated subsidiaries
Noncontrolling interests in consolidated	—			—			4.8			—			4.8
subsidiaries
Total equity	4,458.70			4,458.70			3,470.90			(7,924.8		)	4,463.50
Total liabilities and equity	$	9,271.80		$	9,229.30		$	9,986.80		$	(17,528.7	)	$	10,959.20
Condensed Consolidating Statements of Cash Flows	'
	Condensed Consolidating Statements of Cash Flows
		Nine Months Ended September 30, 2013
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Operating activities
	Cash provided by operating activities	$	641.5		$	48.1		$	634.5		$	(670.0	)	$	654.1
	Investing activities
	Capital expenditures (less allowance for equity	—			—			(1,373.9		)	—			(1,373.9		)
	funds used during construction)
	Acquisition	—			—			(304.9		)	—			(304.9		)
	Contributions to unconsolidated affiliates	—			—			(4.6		)	—			(4.6		)
	Distributions received from unconsolidated	—			17.3			7.6			—			24.9
	affiliates
	Proceeds from sale of assets	—			—			0.7			—			0.7
	Cash provided by (used in) investing activities	—			17.3			(1,675.1		)	—			(1,657.8		)
	Financing activities
	Cash distributions:
	General and limited partners	(670.0		)	(670.0		)	—			670			(670.0		)
	Noncontrolling interests	—			—			(0.4		)	—			(0.4		)
	Borrowing of notes payable, net	47			—			—			—			47
	Issuance of long-term debt, net of discounts	1,247.80			—			—			—			1,247.80
	Long-term debt financing costs	(10.2		)	—			—			—			(10.2		)
	Intercompany borrowings (advances), net	(1,837.2		)	790.5			1,046.70			—			—
	Repayment of long-term debt	—			—			(5.7		)	—			(5.7		)
	Issuance of common units, net of issuance costs	569.2			—			—			—			569.2
	Contribution from general partner	11.9			—			—			—			11.9
	Cash provided by (used in) financing activities	(641.5		)	120.5			1,040.60			670			1,189.60
	Change in cash and cash equivalents	—			185.9			—			—			185.9
	Cash and cash equivalents at beginning of	—			537.1			—			—			537.1
	period
	Cash and cash equivalents at end of period	$	—		$	723		$	—		$	—		$	723
		Nine Months Ended September 30, 2012
	(Unaudited)	Parent			Guarantor			Combined			Consolidating			Total
					Subsidiary			Non-Guarantor			Entries
								Subsidiaries
		(Millions of dollars)
	Operating activities
	Cash provided by operating activities	$	551		$	54.5		$	566		$	(551.0	)	$	620.5
	Investing activities
	Capital expenditures (less allowance for equity	—			—			(1,011.5		)	—			(1,011.5		)
	funds used during construction)
	Contributions to unconsolidated affiliates	—			—			(21.3		)	—			(21.3		)
	Distributions received from unconsolidated	—			16.8			8.9			—			25.7
	affiliates
	Proceeds from sale of assets	—			—			1.7			—			1.7
	Cash provided by (used in) investing activities	—			16.8			(1,022.2		)	—			(1,005.4		)
	Financing activities
	Cash distributions:
	General and limited partners	(551.0		)	(551.0		)	—			551			(551.0		)
	Noncontrolling interests	—			—			(0.6		)	—			(0.6		)
	Issuance of long-term debt, net of discounts	1,295.00			—			—			—			1,295.00
	Long-term debt financing costs	(9.7		)	—			—			—			(9.7		)
	Intercompany borrowings (advances), net	(1,873.9		)	1,408.20			465.7			—			—
	Repayment of long-term debt	(350.0		)	—			(8.9		)	—			(358.9		)
	Issuance of common units, net of issuance costs	919.5			—			—			—			919.5
	Contribution from general partner	19.1			—			—			—			19.1
	Cash provided by (used in) financing activities	(551.0		)	857.2			456.2			551			1,313.40
	Change in cash and cash equivalents	—			928.5			—			—			928.5
	Cash and cash equivalents at beginning of	—			35.1			—			—			35.1
	period
	Cash and cash equivalents at end of period	$	—		$	963.6		$	—		$	—		$	963.6

ACQUISITION_Details

ACQUISITION (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
	MMcf
Acquisition [Abstract]	'	'
Effective date of acquisition	30-Sep-13	'
Acquisition	$304,889	$0
Processing capacity of natural gas processing plant per day	50	'

FAIR_VALUE_MEASUREMENTS_Part_1

FAIR VALUE MEASUREMENTS - Part 1 (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash collateral held	$0	$0
Cash collateral posted	0	0
Fair Value, Measurements, Recurring [Member]	'	'
Derivative assets	'	'
Commodity contracts - financial	16,368	15,127
Commodity contracts - physical	351	'
Interest-rate contracts	43,614	10,923
Total derivative assets	60,333	26,050
Derivative liabilities	'	'
Commodity contracts - financial	0	0
Commodity contracts - physical	-2,712	'
Total derivative liabilities	-2,712	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]	'	'
Derivative assets	'	'
Commodity contracts - financial	0	0
Commodity contracts - physical	0	'
Interest-rate contracts	0	0
Total derivative assets	0	0
Derivative liabilities	'	'
Commodity contracts - financial	0	0
Commodity contracts - physical	0	'
Total derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]	'	'
Derivative assets	'	'
Commodity contracts - financial	15,656	17,581
Commodity contracts - physical	0	'
Interest-rate contracts	43,614	10,923
Total derivative assets	59,270	28,504
Derivative liabilities	'	'
Commodity contracts - financial	-2,150	-31
Commodity contracts - physical	0	'
Total derivative liabilities	-2,150	-31
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]	'	'
Derivative assets	'	'
Commodity contracts - financial	5,148	1
Commodity contracts - physical	351	'
Interest-rate contracts	0	0
Total derivative assets	5,499	1
Derivative liabilities	'	'
Commodity contracts - financial	-2,286	-2,424
Commodity contracts - physical	-2,712	'
Total derivative liabilities	-4,998	-2,424
Fair Value, Measurements, Recurring [Member] | Total Gross, Fair Value Disclosure [Member]	'	'
Derivative assets	'	'
Commodity contracts - financial	20,804	17,582
Commodity contracts - physical	351	'
Interest-rate contracts	43,614	10,923
Total derivative assets	64,769	28,505
Derivative liabilities	'	'
Commodity contracts - financial	-4,436	-2,455
Commodity contracts - physical	-2,712	'
Total derivative liabilities	-7,148	-2,455
Fair Value, Measurements, Recurring [Member] | Netting and Collateral [Member]	'	'
Derivative assets	'	'
Commodity contracts - financial	-4,436	-2,455
Commodity contracts - physical	0	'
Interest-rate contracts	0	0
Total derivative assets	-4,436	-2,455
Derivative liabilities	'	'
Commodity contracts - financial	4,436	2,455
Commodity contracts - physical	0	'
Total derivative liabilities	$4,436	$2,455

FAIR_VALUE_MEASUREMENTS_Part_2

FAIR VALUE MEASUREMENTS - Part 2 (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value, Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]	'	'	'	'
Transfers between levels	$0	$0	$0	$0
Derivative Financial Instruments Assets Liabilities Net [Member]	'	'	'	'
Fair Value, Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Abstract]	'	'	'	'
Net assets (liabilities) at beginning of period	7,682	29,862	-2,423	3,117
Total realized/unrealized gains (losses): [Abstract]	'	'	'	'
Included in other comprehensive income (loss)	-7,181	-19,959	2,924	6,786
Net assets (liabilities) at end of period	$501	$9,903	$501	$9,903

FAIR_VALUE_MEASUREMENTS_Part_3

FAIR VALUE MEASUREMENTS - Part 3 (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Billions, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Long-term Debt, Fair Value	$6.40	$5.60
Senior Notes	$6.10	$4.80

RISK_MANAGEMENT_AND_HEDGING_AC3

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES Part 1 (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Derivative [Line Items]	'	'
Net unrealized loss in accumulated other comprehensive income (loss)	$57,263,000	$99,322,000
Natural Gas Liquids [Member]	'	'
Derivative [Line Items]	'	'
Notional amounts	0	0
Natural Gas Pipelines [Member]	'	'
Derivative [Line Items]	'	'
Notional amounts	0	0
Cash Flow Hedging [Member]	'	'
Derivative [Line Items]	'	'
Net unrealized loss in accumulated other comprehensive income (loss)	57,300,000	'
Cash Flow Hedging [Member] | Fixed Price [Member] | Natural Gas [Member] | Swap [Member] | Purchased [Member]	'	'
Derivative [Line Items]	'	'
Notional amounts	0	0
Cash Flow Hedging [Member] | Fixed Price [Member] | Natural Gas [Member] | Swap [Member] | Sold [Member]	'	'
Derivative [Line Items]	'	'
Notional amounts	49,400	31,700
Cash Flow Hedging [Member] | Fixed Price [Member] | Crude oil and NGLs [Member] | Forwards and Swaps Contracts [Member] | Purchased [Member]	'	'
Derivative [Line Items]	'	'
Notional amounts	0	0
Cash Flow Hedging [Member] | Fixed Price [Member] | Crude oil and NGLs [Member] | Forwards and Swaps Contracts [Member] | Sold [Member]	'	'
Derivative [Line Items]	'	'
Notional amounts	2.3	1.1
Cash Flow Hedging [Member] | Basis [Member] | Natural Gas [Member] | Swap [Member] | Purchased [Member]	'	'
Derivative [Line Items]	'	'
Notional amounts	0	0
Cash Flow Hedging [Member] | Basis [Member] | Natural Gas [Member] | Swap [Member] | Sold [Member]	'	'
Derivative [Line Items]	'	'
Notional amounts	49,400	31,700
Cash Flow Hedging [Member] | Interest Rate Forward Starting Swaps [Member] | Purchased [Member]	'	'
Derivative [Line Items]	'	'
Notional amounts of forward-starting interest rate swaps	400,000,000	400,000,000
Cash Flow Hedging [Member] | Interest Rate Forward Starting Swaps [Member] | Sold [Member]	'	'
Derivative [Line Items]	'	'
Notional amounts of forward-starting interest rate swaps	0	0
Cash Flow Hedging [Member] | Interest Rate Forward Starting Swaps [Member] | Forwards and Swaps Contracts [Member] | Purchased [Member]	'	'
Derivative [Line Items]	'	'
Notional amount of cash flow hedge instruments with settlement dates greater than 12 months	400,000,000	400,000,000
Commodity Contract [Member] | Cash Flow Hedging [Member]	'	'
Derivative [Line Items]	'	'
Cash flow hedge gain to be reclassified within 27 months	14,000,000	'
Commodity cash flow hedge gain to be reclassified within 12 months	6,100,000	'
Amount of gains to be reclassified after 12 months	7,900,000	'
Interest Rate Contract [Member] | Cash Flow Hedging [Member]	'	'
Derivative [Line Items]	'	'
Amount of loss deferred in accumulated other comprehensive income (loss) attributable to settled interest-rate swaps	112,100,000	'
Amount of losses to be reclassified over the next 12 months	10,100,000	'
Designated as Hedging Instrument [Member]	'	'
Derivative [Line Items]	'	'
Assets	64,769,000	28,505,000
(Liabilities)	-7,148,000	-2,455,000
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]	'	'
Derivative [Line Items]	'	'
Assets	43,614,000	10,923,000
(Liabilities)	0	0
Designated as Hedging Instrument [Member] | Financial Derivative Instrument [Member] | Commodity Contract [Member]	'	'
Derivative [Line Items]	'	'
Assets	20,804,000	17,582,000
(Liabilities)	-4,436,000	-2,455,000
Designated as Hedging Instrument [Member] | Physical Derivative Instrument [Member] | Commodity Contract [Member]	'	'
Derivative [Line Items]	'	'
Assets	351,000	0
(Liabilities)	($2,712,000)	$0

RISK_MANAGEMENT_AND_HEDGING_AC4

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES, Part 2 (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Commodity Contract [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income (effective portion)	$361,000	'	$4,172,000	'
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)	-2,565,000	'	-7,445,000	'
Cash Flow Hedging [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Total gain (loss) recognized in other comprehensive income (loss) (effective portion)	-3,596,000	-19,361,000	38,786,000	1,637,000
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income (effective portion)	-2,204,000	19,852,000	-3,273,000	42,647,000
Gain (Loss) on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	0	0	0	0
Cash Flow Hedging [Member] | Commodity Contract [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Total gain (loss) recognized in other comprehensive income (loss) (effective portion)	-10,317,000	-18,186,000	3,060,000	41,469,000
Cash Flow Hedging [Member] | Commodity Contract [Member] | Sales [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income (effective portion)	361,000	20,549,000	4,172,000	43,527,000
Cash Flow Hedging [Member] | Interest Rate Contract [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Total gain (loss) recognized in other comprehensive income (loss) (effective portion)	6,721,000	-1,175,000	35,726,000	-39,832,000
Cash Flow Hedging [Member] | Interest Rate Contract [Member] | Interest Expense [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income (effective portion)	($2,565,000)	($697,000)	($7,445,000)	($880,000)

CREDIT_FACILITY_AND_SHORTTERM_1

CREDIT FACILITY AND SHORT-TERM NOTES PAYABLE (Details) (USD $)	9 Months Ended
	Sep. 30, 2013
Partnership Credit Agreement [Member]	'
Line of Credit Facility [Line Items]	'
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	4.2
Maximum borrowing capacity	1,200,000,000
Partnership Credit Agreement sublimit for issuance of standby letters of credit	100,000,000
Option to increase borrowing capacity	1,700,000,000
Interest rate description	'Borrowings, if any, will accrue at LIBOR plus 130 basis points,
Annual fee description	'the annual facility fee is 20 basis points based on our current credit rating.
Letters of Credit Outstanding, Amount	0
Short-term Bank Loans and Notes Payable	0
ONEOK Partners 2011 Credit Agreement [Member]	'
Line of Credit Facility [Line Items]	'
Commercial Paper	$47,000,000

LONGTERM_DEBT_Details

LONG-TERM DEBT (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2012	Mar. 31, 2012
	Partnership Interest [Member]	Partnership Interest [Member]	Partnership Interest [Member]	Partnership Interest [Member]	Partnership Interest [Member]	Senior Notes [Member]	Senior Notes [Member]	Senior Notes [Member]	Notes Payables due 2012 [Member]	Notes Payables due 2012 [Member]
	Note Payable from Public Offering Due 2018 [Member]	Note Payable from Public Offering Due 2023 [Member]	Note Payable from Public Offering Due 2043 [Member]	Note Payable from Public Offering Due 2017 [Member]	Note Payable from Public Offering Due 2022 [Member]		Partnership Interest [Member]	Partnership Interest [Member]	Partnership Interest [Member]	Partnership Interest [Member]
Debt Instrument [Line Items]	'	'	'	'	'	'	'	'	'	'
Senior Notes, Noncurrent	'	'	'	'	'	'	$1,250,000,000	$1,300,000,000	'	'
Long-term Debt, Gross	425,000,000	425,000,000	400,000,000	400,000,000	900,000,000	'	'	'	'	350,000,000
Interest rates (in hundredths)	3.20%	5.00%	6.20%	2.00%	3.38%	'	'	'	'	5.90%
Proceeds from Debt, Net of Issuance Costs	'	'	'	'	'	'	$1,240,000,000	$1,290,000,000	'	'
Debt Instrument, Covenant Description	'	'	'	'	'	'These notes are governed by an indenture, dated as of September 25, 2006, between us and Wells Fargo Bank, N.A., the trustee, as supplemented.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. 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.	'	'	'	'
Debt Instrument, Call Feature	'	'	'	'	'	'We may redeem our 3.2 percent senior notes due 2018, our 5.0 percent senior notes due 2023, and our 6.2 percent senior notes due 2043 from the September 2013 offering at par, plus accrued and unpaid interest to the redemption date, starting one month, three months, and six months, respectively, before their maturity dates.B B 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.B B 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.B B Our senior notes are senior unsecured obligations, ranking equally in right of payment with all of our existing and future unsecured senior indebtedness, and structurally subordinate to any of the existing and future debt and other liabilities of any nonguarantor subsidiaries.	'	'	'	'
Year of maturity	'	'	'	'	'	'	'	'	1-Apr-12	'

EQUITY_Details

EQUITY (Details) (USD $)

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

Share data in Millions, except Per Share data, unless otherwise specified

Sep. 30, 2013

Mar. 31, 2013

Mar. 31, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2012

Mar. 31, 2012

Sep. 30, 2013

Distribution Paid [Member]

Distribution Paid [Member]

Distribution Paid [Member]

Distribution Paid [Member]

Distribution Declared [Member]

Distribution Declared [Member]

Distribution Declared [Member]

Distribution Declared [Member]

General Partner [Member]

General Partner [Member]

General Partner [Member]

General Partner [Member]

General Partner [Member]

General Partner [Member]

General Partner [Member]

General Partner [Member]

General Partner [Member]

Limited Partner [Member]

Limited Partner [Member]

Limited Partner [Member]

Limited Partner [Member]

Limited Partner [Member]

Limited Partner [Member]

Limited Partner [Member]

Limited Partner [Member]

Notes Payables due 2012 [Member]

Notes Payables due 2012 [Member]

Partnership Credit Agreement [Member]

Distribution Paid [Member]

Distribution Paid [Member]

Distribution Paid [Member]

Distribution Paid [Member]

Distribution Declared [Member]

Distribution Declared [Member]

Distribution Declared [Member]

Distribution Declared [Member]

Distribution Paid [Member]

Distribution Paid [Member]

Distribution Paid [Member]

Distribution Paid [Member]

Distribution Declared [Member]

Distribution Declared [Member]

Distribution Declared [Member]

Distribution Declared [Member]

Partnership Interest [Member]

Partnership Interest [Member]

Equity [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of common units owned by related party (in number of units)

19.8

'

'

19.8

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

General partnership ownership interest (in hundredths)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum borrowing capacity

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1,200,000,000

General partnership ownership interest (in hundreths)

41.30%

'

'

41.30%

'

43.40%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate amount of common units available for issuance and sale under the Equity Distribution Agreement

'

'

'

300,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Underwritten public offering of common units (in number of units)

11.5

'

8

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Public offering price of common units (in dollars per unit)

$49.61

'

$59.27

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net proceeds generated from public offering

553,400,000

16,300,000

460,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of common units to related party in a private placement (in number of units)

'

'

8

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds generated from the sale of common units to related party in private placement

'

'

460,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Contribution from general partner

11,600,000

'

19,000,000

11,967,000

19,069,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Partnership Capital Distributions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Distribution per unit

'

'

'

'

'

'

$0.72

$0.66

$2.15

$1.91

$0.73

$0.69

$2.16

$1.98

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Distribution Made To Member Or Limited Parter Annualized Quarterly Distribution

'

'

'

'

'

'

'

'

'

'

2.9

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

General partner distributions

'

'

'

'

'

'

67,146,000

53,865,000

198,046,000

141,987,000

71,812,000

59,361,000

205,002,000

161,595,000

'

4,512,000

3,979,000

13,399,000

11,019,000

4,795,000

4,199,000

13,776,000

11,937,000

'

'

'

'

'

'

'

'

'

'

'

Incentive distributions

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

62,634,000

49,886,000

184,647,000

130,968,000

67,017,000

55,162,000

191,226,000

149,658,000

'

'

'

'

'

'

'

'

'

'

'

Limited partner distributions to ONEOK

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

66,807,000

61,240,000

199,031,000

171,882,000

67,271,000

63,560,000

200,422,000

183,721,000

'

'

'

Cash distributions: noncontrolling interests

'

'

'

-442,000

-636,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

91,676,000

83,838,000

272,904,000

237,109,000

100,650,000

87,014,000

283,365,000

251,514,000

'

'

'

Total distributions

'

'

'

670,423,000

'

'

225,629,000

198,943,000

669,981,000

550,978,000

239,733,000

209,935,000

688,789,000

596,830,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Distribution Made To Member Or Limited Parter Change From Prior Quarter

0.005

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Distribution Made to Member or Limited Partner, Distribution Date

14-Nov-13

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Distribution Made to Member or Limited Partner, Date of Record

4-Nov-13

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt, Gross

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$350,000,000

'

Year of maturity

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1-Apr-12

'

'

Interest rates (in hundredths)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.90%

'

ACCUMULATED_OTHER_COMPREHENSIV2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accumulated other comprehensive loss - January 1, 2013	'	'	($99,322)	'
Other comprehensive income (loss) before reclassifications	-3,596	-19,361	38,786	1,637
Total amounts reclassified from accumulated other comprehensive income (loss)	2,204	-19,852	3,273	-42,647
Net current-period other comprehensive income (loss) attributable to ONEOK Partners, L.P.	-1,392	-39,213	42,059	-41,010
Accumulated other comprehensive loss - September 30, 2013	-57,263	'	-57,263	'
Cash Flow Hedging [Member]	'	'	'	'
Amounts reclassified from accumulated other comprehensive income (loss)	2,204	-19,852	3,273	-42,647
Accumulated other comprehensive loss - September 30, 2013	-57,300	'	-57,300	'
Interest Rate Contract [Member]	'	'	'	'
Amounts reclassified from accumulated other comprehensive income (loss)	2,565	'	7,445	'
Interest Rate Contract [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]	'	'	'	'
Amounts reclassified from accumulated other comprehensive income (loss)	2,565	697	7,445	880
Commodity Contract [Member]	'	'	'	'
Amounts reclassified from accumulated other comprehensive income (loss)	-361	'	-4,172	'
Commodity Contract [Member] | Sales [Member] | Cash Flow Hedging [Member]	'	'	'	'
Amounts reclassified from accumulated other comprehensive income (loss)	($361)	($20,549)	($4,172)	($43,527)

LIMITED_PARTNERS_NET_INCOME_PE1

LIMITED PARTNERS' NET INCOME PER UNIT (Details)	9 Months Ended
	Sep. 30, 2013
Limited Partners' Net Income Per Unit and Distributions to Partners [Abstract]	'
Number of days notice of withdrawal of waiver	90
General Partner [Member]	'
Limited Partners' Net Income Per Unit and Distributions to Partners [Abstract]	'
General partnership ownership interest (in hundredths)	2.00%

UNCONSOLIDATED_AFFILIATES_Deta

UNCONSOLIDATED AFFILIATES (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Equity earnings from investments	$27,468,000	$28,591,000	$79,744,000	$92,380,000	'
Investments in unconsolidated affiliates	1,201,873,000	1,218,282,000	1,201,873,000	1,218,282,000	1,221,405,000
Income Statement [Abstract]	'	'	'	'	'
Operating revenues	131,959,000	125,828,000	391,912,000	373,038,000	'
Operating expenses	63,971,000	60,937,000	189,366,000	173,232,000	'
Net income	61,630,000	55,721,000	185,580,000	180,787,000	'
Distributions paid to us	34,409,000	34,557,000	103,913,000	118,752,000	'
Northern Border Pipeline [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Equity earnings from investments	16,464,000	18,185,000	48,133,000	54,493,000	'
Percentage decrease in long-term transportation rates	'	'	11.00%	'	'
Overland Pass Pipeline Company [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Equity earnings from investments	5,783,000	4,490,000	14,210,000	15,786,000	'
Fort Union Gas Gathering LLC [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Equity earnings from investments	2,946,000	4,091,000	9,895,000	11,494,000	'
Bighorn Gas Gathering LLC [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Equity earnings from investments	559,000	1,157,000	1,897,000	3,118,000	'
Ownership in Bighorn Gas Gathering, LLC	49.00%	'	49.00%	'	'
Investments in unconsolidated affiliates	88,700,000	'	88,700,000	'	'
Equity method goodwill included in Bighorn Gas Gathering, LLC	53,400,000	'	53,400,000	'	'
Other Unconsolidated Affiliate [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Equity earnings from investments	1,716,000	668,000	5,609,000	7,489,000	'
Unconsolidated Affiliates [Member]	'	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'
Costs and operating expenses with equity method investees	$15,900,000	$9,000,000	$36,300,000	$27,300,000	'

RELATEDPARTY_TRANSACTIONS_Deta

RELATED-PARTY TRANSACTIONS (Details) (USD $)	3 Months Ended			9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2012	Sep. 30, 2013	Sep. 30, 2012
Related Party Transaction [Line Items]	'	'	'	'	'
Contribution from general partner	$11,600	'	$19,000	$11,967	$19,069
Revenues	81,324	91,096	'	255,298	247,851
General Partner [Member]	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'
General partnership ownership interest (in hundredths)	'	'	'	2.00%	'
ONEOK [Member]	'	'	'	'	'
Related Party Transaction [Line Items]	'	'	'	'	'
Revenues	81,324	91,096	'	255,298	247,851
Expenses [Abstract]	'	'	'	'	'
Cost of sales and fuel	9,562	7,831	'	27,855	22,875
Administrative and general expenses	58,549	60,020	'	192,906	179,017
Total expenses	$68,111	$67,851	'	$220,761	$201,892

COMMITMENTS_AND_CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES (Details)	Sep. 30, 2013
	Y
Commitments and Contingencies Disclosure [Abstract]	'
Number of years of consideration for EPA lowering threshold levels for greenhouse gas emissions	5

SEGMENTS_Details

SEGMENTS (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]	'	'	'	'	'
Net Income (Loss) Attributable to Noncontrolling Interest	$90	$102	$263	$336	'
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.	'we had no single customer from which we received 10 percent or more of our consolidated revenues.	'
Segment disclosure [Abstract]	'	'	'	'	'
Sales to unaffiliated customers	3,053,409	2,456,364	8,165,061	7,018,503	'
Sales to affiliated customers	81,324	91,096	255,298	247,851	'
Intersegment revenues	0	0	0	0	'
Total revenues	3,134,733	2,547,460	8,420,359	7,266,354	'
Net margin	423,574	419,737	1,206,126	1,242,289	'
Operating costs	122,362	121,176	384,602	360,410	'
Depreciation and amortization	61,182	49,754	174,086	150,024	'
Gain (loss) on sale of assets	22	-420	342	603	'
Operating income	240,052	248,387	647,780	732,458	'
Equity earnings from investments	27,468	28,591	79,744	92,380	'
Investments in unconsolidated affiliates	1,201,873	1,218,282	1,201,873	1,218,282	1,221,405
Total assets	12,863,326	10,792,593	12,863,326	10,792,593	10,959,230
Noncontrolling interests in consolidated subsidiaries	4,588	4,812	4,588	4,812	4,767
Capital expenditures	'	375,291	1,373,904	1,011,527	'
Natural Gas Gathering and Processing [Member]	'	'	'	'	'
Segment disclosure [Abstract]	'	'	'	'	'
Sales to unaffiliated customers	162,677	114,127	466,631	307,145	'
Sales to affiliated customers	57,400	67,269	179,636	177,213	'
Intersegment revenues	312,940	197,733	806,523	588,379	'
Total revenues	533,017	379,129	1,452,790	1,072,737	'
Net margin	130,882	115,869	365,436	332,305	'
Operating costs	45,074	39,371	141,737	120,857	'
Depreciation and amortization	27,356	19,565	76,366	61,335	'
Gain (loss) on sale of assets	31	25	344	1,154	'
Operating income	58,483	56,958	147,677	151,267	'
Equity earnings from investments	4,668	5,546	16,228	21,031	'
Investments in unconsolidated affiliates	331,124	323,503	331,124	323,503	'
Total assets	3,808,135	2,797,692	3,808,135	2,797,692	'
Noncontrolling interests in consolidated subsidiaries	4,574	0	4,574	0	'
Capital expenditures	204,542	157,714	574,509	435,122	'
Natural Gas Pipelines [Member]	'	'	'	'	'
Segment disclosure [Abstract]	'	'	'	'	'
Sales to unaffiliated customers	50,624	55,046	158,960	157,067	'
Sales to affiliated customers	23,924	23,827	75,662	70,638	'
Intersegment revenues	1,330	910	2,327	2,788	'
Total revenues	75,878	79,783	236,949	230,493	'
Net margin	69,457	71,402	211,224	212,002	'
Operating costs	23,457	26,265	75,608	78,291	'
Depreciation and amortization	10,833	11,592	32,687	34,525	'
Gain (loss) on sale of assets	-16	-83	-12	-95	'
Operating income	35,151	33,462	102,917	99,091	'
Equity earnings from investments	16,464	18,314	48,133	54,971	'
Investments in unconsolidated affiliates	376,047	406,471	376,047	406,471	'
Total assets	1,786,413	1,855,209	1,786,413	1,855,209	'
Noncontrolling interests in consolidated subsidiaries	0	4,797	0	4,797	'
Capital expenditures	11,148	5,119	22,497	14,584	'
Natural Gas Pipelines [Member] | Natural Gas Pipelines for Regulated Segment [Member]	'	'	'	'	'
Segment disclosure [Abstract]	'	'	'	'	'
Total revenues	57,500	62,400	182,000	179,100	'
Net margin	52,800	54,900	162,500	162,500	'
Operating income	22,600	22,800	67,000	66,800	'
Natural Gas Liquids [Member]	'	'	'	'	'
Segment disclosure [Abstract]	'	'	'	'	'
Sales to unaffiliated customers	2,840,108	2,287,191	7,539,470	6,554,291	'
Sales to affiliated customers	0	0	0	0	'
Intersegment revenues	34,740	23,777	91,161	55,902	'
Total revenues	2,874,848	2,310,968	7,630,631	6,610,193	'
Net margin	226,242	234,546	632,087	703,657	'
Operating costs	57,010	56,756	171,076	166,622	'
Depreciation and amortization	22,993	18,588	65,033	54,155	'
Gain (loss) on sale of assets	7	-362	10	-456	'
Operating income	146,246	158,840	395,988	482,424	'
Equity earnings from investments	6,336	4,731	15,383	16,378	'
Investments in unconsolidated affiliates	494,702	488,308	494,702	488,308	'
Total assets	6,610,205	5,169,516	6,610,205	5,169,516	'
Noncontrolling interests in consolidated subsidiaries	0	0	0	0	'
Capital expenditures	230,780	212,331	774,284	561,492	'
Natural Gas Liquids [Member] | Natural Gas Liquids for Regulated Segment [Member]	'	'	'	'	'
Segment disclosure [Abstract]	'	'	'	'	'
Intersegment revenues	130,200	103,700	321,300	285,800	'
Total revenues	147,100	119,200	376,900	333,900	'
Net margin	89,500	68,000	227,800	197,200	'
Operating income	53,400	40,800	129,000	115,500	'
Other and Eliminations	'	'	'	'	'
Segment disclosure [Abstract]	'	'	'	'	'
Sales to unaffiliated customers	0	0	0	0	'
Sales to affiliated customers	0	0	0	0	'
Intersegment revenues	-349,010	-222,420	-900,011	-647,069	'
Total revenues	-349,010	-222,420	-900,011	-647,069	'
Net margin	-3,007	-2,080	-2,621	-5,675	'
Operating costs	-3,179	-1,216	-3,819	-5,360	'
Depreciation and amortization	0	9	0	9	'
Gain (loss) on sale of assets	0	0	0	0	'
Operating income	172	-873	1,198	-324	'
Equity earnings from investments	0	0	0	0	'
Investments in unconsolidated affiliates	0	0	0	0	'
Total assets	658,573	970,176	658,573	970,176	'
Noncontrolling interests in consolidated subsidiaries	14	15	14	15	'
Capital expenditures	2,602	127	2,614	329	'
Oneok Partners [Member]	'	'	'	'	'
Segment disclosure [Abstract]	'	'	'	'	'
Capital expenditures	$449,072	'	$1,373,904	'	'

SUPPLEMENTAL_CONDENSED_CONSOLI2

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Income Statement (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	$3,134,733,000	$2,547,460,000	$8,420,359,000	$7,266,354,000
Cost of sales and fuel	2,711,159,000	2,127,723,000	7,214,233,000	6,024,065,000
Net margin	423,574,000	419,737,000	1,206,126,000	1,242,289,000
Operating expenses	'	'	'	'
Operations and maintenance	108,978,000	110,268,000	338,353,000	319,905,000
Depreciation and amortization	61,182,000	49,754,000	174,086,000	150,024,000
General taxes	13,384,000	10,908,000	46,249,000	40,505,000
Total operating expenses	183,544,000	170,930,000	558,688,000	510,434,000
Gain on sale of assets	22,000	-420,000	342,000	603,000
Operating income	240,052,000	248,387,000	647,780,000	732,458,000
Equity earnings from investments	27,468,000	28,591,000	79,744,000	92,380,000
Allowance for equity funds used during construction	6,429,000	3,302,000	21,172,000	6,126,000
Other income	3,753,000	2,971,000	8,229,000	6,567,000
Other expense	-589,000	-472,000	-2,447,000	-2,104,000
Interest expense	-57,722,000	-47,776,000	-171,118,000	-148,110,000
Income before income taxes	219,391,000	235,003,000	583,360,000	687,317,000
Income taxes	-2,991,000	-2,626,000	-7,821,000	-9,396,000
Net income	216,400,000	232,377,000	575,539,000	677,921,000
Less: Net income attributable to noncontrolling interests	90,000	102,000	263,000	336,000
Net income attributable to ONEOK Partners, L.P.	216,310,000	232,275,000	575,276,000	677,585,000
Parent [member]	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	0	0	0	0
Cost of sales and fuel	0	0	0	0
Net margin	0	0	0	0
Operating expenses	'	'	'	'
Operations and maintenance	0	0	0	0
Depreciation and amortization	0	0	0	0
General taxes	0	0	0	0
Total operating expenses	0	0	0	0
Gain on sale of assets	'	0	0	0
Operating income	0	0	0	0
Equity earnings from investments	216,300,000	232,300,000	575,300,000	677,600,000
Allowance for equity funds used during construction	0	0	0	0
Other income (expense), net	70,600,000	46,200,000	205,100,000	143,200,000
Interest expense	-70,600,000	-46,200,000	-205,100,000	-143,200,000
Income before income taxes	216,300,000	232,300,000	575,300,000	677,600,000
Income taxes	0	0	0	0
Net income	216,300,000	232,300,000	575,300,000	677,600,000
Less: Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to ONEOK Partners, L.P.	216,300,000	232,300,000	575,300,000	677,600,000
Guarantor Subsidiary [member]	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	0	0	0	0
Cost of sales and fuel	0	0	0	0
Net margin	0	0	0	0
Operating expenses	'	'	'	'
Operations and maintenance	0	0	0	0
Depreciation and amortization	0	0	0	0
General taxes	0	0	0	0
Total operating expenses	0	0	0	0
Gain on sale of assets	'	0	0	0
Operating income	0	0	0	0
Equity earnings from investments	216,300,000	232,300,000	575,300,000	677,600,000
Allowance for equity funds used during construction	0	0	0	0
Other income (expense), net	70,600,000	46,200,000	205,100,000	143,200,000
Interest expense	-70,600,000	-46,200,000	-205,100,000	-143,200,000
Income before income taxes	216,300,000	232,300,000	575,300,000	677,600,000
Income taxes	0	0	0	0
Net income	216,300,000	232,300,000	575,300,000	677,600,000
Less: Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to ONEOK Partners, L.P.	216,300,000	232,300,000	575,300,000	677,600,000
Combined Non-Guarantor Subsidiaries [member]	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	3,134,700,000	2,547,500,000	8,420,400,000	7,266,400,000
Cost of sales and fuel	2,711,100,000	2,127,800,000	7,214,300,000	6,024,100,000
Net margin	423,600,000	419,700,000	1,206,100,000	1,242,300,000
Operating expenses	'	'	'	'
Operations and maintenance	109,000,000	110,300,000	338,400,000	319,900,000
Depreciation and amortization	61,200,000	49,700,000	174,100,000	150,000,000
General taxes	13,300,000	10,900,000	46,200,000	40,500,000
Total operating expenses	183,500,000	170,900,000	558,700,000	510,400,000
Gain on sale of assets	'	-400,000	400,000	600,000
Operating income	240,100,000	248,400,000	647,800,000	732,500,000
Equity earnings from investments	11,000,000	10,400,000	31,600,000	37,900,000
Allowance for equity funds used during construction	6,400,000	3,300,000	21,200,000	6,100,000
Other income (expense), net	3,100,000	2,500,000	5,800,000	4,400,000
Interest expense	-57,700,000	-47,800,000	-171,100,000	-148,100,000
Income before income taxes	202,900,000	216,800,000	535,300,000	632,800,000
Income taxes	-3,000,000	-2,600,000	-7,900,000	-9,400,000
Net income	199,900,000	214,200,000	527,400,000	623,400,000
Less: Net income attributable to noncontrolling interests	100,000	100,000	200,000	300,000
Net income attributable to ONEOK Partners, L.P.	199,800,000	214,100,000	527,200,000	623,100,000
Consolidating Entries [member]	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	0	0	0	0
Cost of sales and fuel	0	0	0	0
Net margin	0	0	0	0
Operating expenses	'	'	'	'
Operations and maintenance	0	0	0	0
Depreciation and amortization	0	0	0	0
General taxes	0	0	0	0
Total operating expenses	0	0	0	0
Gain on sale of assets	'	0	0	0
Operating income	0	0	0	0
Equity earnings from investments	-416,100,000	-446,400,000	-1,102,500,000	-1,300,700,000
Allowance for equity funds used during construction	0	0	0	0
Other income (expense), net	-141,200,000	-92,400,000	-410,200,000	-286,400,000
Interest expense	141,200,000	92,400,000	410,200,000	286,400,000
Income before income taxes	-416,100,000	-446,400,000	-1,102,500,000	-1,300,700,000
Income taxes	0	0	0	0
Net income	-416,100,000	-446,400,000	-1,102,500,000	-1,300,700,000
Less: Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to ONEOK Partners, L.P.	-416,100,000	-446,400,000	-1,102,500,000	-1,300,700,000
Total [Member]	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Revenues	3,134,700,000	2,547,500,000	8,420,400,000	7,266,400,000
Cost of sales and fuel	2,711,100,000	2,127,800,000	7,214,300,000	6,024,100,000
Net margin	423,600,000	419,700,000	1,206,100,000	1,242,300,000
Operating expenses	'	'	'	'
Operations and maintenance	109,000,000	110,300,000	338,400,000	319,900,000
Depreciation and amortization	61,200,000	49,700,000	174,100,000	150,000,000
General taxes	13,300,000	10,900,000	46,200,000	40,500,000
Total operating expenses	183,500,000	170,900,000	558,700,000	510,400,000
Gain on sale of assets	'	-400,000	400,000	600,000
Operating income	240,100,000	248,400,000	647,800,000	732,500,000
Equity earnings from investments	27,500,000	28,600,000	79,700,000	92,400,000
Allowance for equity funds used during construction	6,400,000	3,300,000	21,200,000	6,100,000
Other income (expense), net	3,100,000	2,500,000	5,800,000	4,400,000
Interest expense	-57,700,000	-47,800,000	-171,100,000	-148,100,000
Income before income taxes	219,400,000	235,000,000	583,400,000	687,300,000
Income taxes	-3,000,000	-2,600,000	-7,900,000	-9,400,000
Net income	216,400,000	232,400,000	575,500,000	677,900,000
Less: Net income attributable to noncontrolling interests	100,000	100,000	200,000	300,000
Net income attributable to ONEOK Partners, L.P.	$216,300,000	$232,300,000	$575,300,000	$677,600,000

SUPPLEMENTAL_CONDENSED_CONSOLI3

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Comprehensive Income (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net income	$216,400	$232,377	$575,539	$677,921
Other comprehensive income (loss)	'	'	'	'
Unrealized gains (losses) on derivatives	-3,596	-19,361	38,786	1,637
Realized (gains) losses on derivatives recognized in net income	2,204	-19,852	3,273	-42,647
Total other comprehensive income (loss)	-1,392	-39,213	42,059	-41,010
Comprehensive income	215,008	193,164	617,598	636,911
Less: Comprehensive income attributable to noncontrolling interests	90	102	263	336
Comprehensive income attributable to ONEOK Partners, L.P.	214,918	193,062	617,335	636,575
Parent [member]	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net income	216,300	232,300	575,300	677,600
Other comprehensive income (loss)	'	'	'	'
Unrealized gains (losses) on derivatives	-3,600	-19,400	38,800	1,600
Realized (gains) losses on derivatives recognized in net income	2,200	-19,800	3,200	-42,600
Total other comprehensive income (loss)	-1,400	-39,200	42,000	-41,000
Comprehensive income	214,900	193,100	617,300	636,600
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to ONEOK Partners, L.P.	214,900	193,100	617,300	636,600
Guarantor Subsidiary [member]	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net income	216,300	232,300	575,300	677,600
Other comprehensive income (loss)	'	'	'	'
Unrealized gains (losses) on derivatives	-10,300	-18,200	3,100	41,500
Realized (gains) losses on derivatives recognized in net income	-400	-20,500	-4,200	-43,500
Total other comprehensive income (loss)	-10,700	-38,700	-1,100	-2,000
Comprehensive income	205,600	193,600	574,200	675,600
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to ONEOK Partners, L.P.	205,600	193,600	574,200	675,600
Combined Non-Guarantor Subsidiaries [member]	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net income	199,900	214,200	527,400	623,400
Other comprehensive income (loss)	'	'	'	'
Unrealized gains (losses) on derivatives	-10,300	-18,200	3,100	41,500
Realized (gains) losses on derivatives recognized in net income	-400	-20,500	-4,200	-43,500
Total other comprehensive income (loss)	-10,700	-38,700	-1,100	-2,000
Comprehensive income	189,200	175,500	526,300	621,400
Less: Comprehensive income attributable to noncontrolling interests	100	100	200	300
Comprehensive income attributable to ONEOK Partners, L.P.	189,100	175,400	526,100	621,100
Consolidating Entries [member]	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net income	-416,100	-446,400	-1,102,500	-1,300,700
Other comprehensive income (loss)	'	'	'	'
Unrealized gains (losses) on derivatives	20,600	36,400	-6,200	-83,000
Realized (gains) losses on derivatives recognized in net income	800	41,000	8,400	87,000
Total other comprehensive income (loss)	21,400	77,400	2,200	4,000
Comprehensive income	-394,700	-369,000	-1,100,300	-1,296,700
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	0
Comprehensive income attributable to ONEOK Partners, L.P.	-394,700	-369,000	-1,100,300	-1,296,700
Total [Member]	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'
Net income	216,400	232,400	575,500	677,900
Other comprehensive income (loss)	'	'	'	'
Unrealized gains (losses) on derivatives	-3,600	-19,400	38,800	1,600
Realized (gains) losses on derivatives recognized in net income	2,200	-19,800	3,200	-42,600
Total other comprehensive income (loss)	-1,400	-39,200	42,000	-41,000
Comprehensive income	215,000	193,200	617,500	636,900
Less: Comprehensive income attributable to noncontrolling interests	100	100	200	300
Comprehensive income attributable to ONEOK Partners, L.P.	$214,900	$193,100	$617,300	$636,600

SUPPLEMENTAL_CONDENSED_CONSOLI4

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Balance Sheet (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Current assets	'	'	'	'
Cash and cash equivalents	$723,030,000	$537,074,000	$963,648,000	$35,091,000
Accounts receivable, net	956,575,000	914,036,000	'	'
Affiliate receivables	13,227,000	16,092,000	'	'
Gas and natural gas liquids in storage	390,629,000	235,836,000	'	'
Commodity imbalances	93,722,000	89,704,000	'	'
Other current assets	83,829,000	98,966,000	'	'
Total current assets	2,261,012,000	1,891,708,000	'	'
Property, plant and equipment	'	'	'	'
Property, plant and equipment	10,245,377,000	8,585,142,000	'	'
Accumulated depreciation and amortization	1,595,814,000	1,440,871,000	'	'
Net property, plant and equipment	8,649,563,000	7,144,271,000	'	'
Investments and other assets	'	'	'	'
Investments in unconsolidated affiliates	1,201,873,000	1,221,405,000	1,218,282,000	'
Goodwill and intangible assets	640,122,000	645,871,000	'	'
Other assets	110,756,000	55,975,000	'	'
Total investments and other assets	1,952,751,000	1,923,251,000	'	'
Total assets	12,863,326,000	10,959,230,000	10,792,593,000	'
Current liabilities	'	'	'	'
Current maturities of long-term debt	7,650,000	7,650,000	'	'
Notes payable	47,000,000	0	'	'
Accounts payable	1,202,049,000	1,058,007,000	'	'
Affiliate payables	43,934,000	75,710,000	'	'
Commodity imbalances	228,207,000	273,173,000	'	'
Accrued interest	88,545,000	76,734,000	'	'
Other current liabilities	99,465,000	79,158,000	'	'
Total current liabilities	1,716,850,000	1,570,432,000	'	'
Long-term debt, excluding current maturities	6,046,494,000	4,803,629,000	'	'
Deferred credits and other liabilities	108,087,000	121,662,000	'	'
Commitments and contingencies	'	'	'	'
Equity	'	'	'	'
Equity excluding noncontrolling interests in consolidated subsidiaries	4,987,307,000	4,458,740,000	'	'
Noncontrolling interests in consolidated subsidiaries	4,588,000	4,767,000	4,812,000	'
Total equity	4,991,895,000	4,463,507,000	'	'
Total liabilities and equity	12,863,326,000	10,959,230,000	'	'
Parent [member]	'	'	'	'
Current assets	'	'	'	'
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0	'	'
Affiliate receivables	0	0	'	'
Gas and natural gas liquids in storage	0	0	'	'
Commodity imbalances	0	0	'	'
Other current assets	0	10,900,000	'	'
Total current assets	0	10,900,000	'	'
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	4,362,900,000	4,458,700,000	'	'
Intercompany notes receivable	6,662,100,000	4,770,600,000	'	'
Goodwill and intangible assets	0	0	'	'
Other assets	82,800,000	31,600,000	'	'
Total investments and other assets	11,107,800,000	9,260,900,000	'	'
Total assets	11,107,800,000	9,271,800,000	'	'
Current liabilities	'	'	'	'
Current maturities of long-term debt	0	0	'	'
Notes payable	47,000,000	'	'	'
Accounts payable	0	0	'	'
Affiliate payables	0	0	'	'
Commodity imbalances	0	0	'	'
Accrued interest	88,500,000	76,700,000	'	'
Other current liabilities	0	0	'	'
Total current liabilities	135,500,000	76,700,000	'	'
Intercompany debt	0	0	'	'
Long-term debt, excluding current maturities	5,985,000,000	4,736,400,000	'	'
Deferred credits and other liabilities	0	0	'	'
Equity	'	'	'	'
Equity excluding noncontrolling interests in consolidated subsidiaries	4,987,300,000	4,458,700,000	'	'
Noncontrolling interests in consolidated subsidiaries	0	0	'	'
Total equity	4,987,300,000	4,458,700,000	'	'
Total liabilities and equity	11,107,800,000	9,271,800,000	'	'
Guarantor Subsidiary [member]	'	'	'	'
Current assets	'	'	'	'
Cash and cash equivalents	723,000,000	537,100,000	963,600,000	35,100,000
Accounts receivable, net	0	0	'	'
Affiliate receivables	0	0	'	'
Gas and natural gas liquids in storage	0	0	'	'
Commodity imbalances	0	0	'	'
Other current assets	0	0	'	'
Total current assets	723,000,000	537,100,000	'	'
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	4,367,900,000	3,858,900,000	'	'
Intercompany notes receivable	5,934,100,000	4,833,300,000	'	'
Goodwill and intangible assets	0	0	'	'
Other assets	0	0	'	'
Total investments and other assets	10,302,000,000	8,692,200,000	'	'
Total assets	11,025,000,000	9,229,300,000	'	'
Current liabilities	'	'	'	'
Current maturities of long-term debt	0	0	'	'
Notes payable	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	6,662,100,000	4,770,600,000	'	'
Long-term debt, excluding current maturities	0	0	'	'
Deferred credits and other liabilities	0	0	'	'
Equity	'	'	'	'
Equity excluding noncontrolling interests in consolidated subsidiaries	4,362,900,000	4,458,700,000	'	'
Noncontrolling interests in consolidated subsidiaries	0	0	'	'
Total equity	4,362,900,000	4,458,700,000	'	'
Total liabilities and equity	11,025,000,000	9,229,300,000	'	'
Combined Non-Guarantor Subsidiaries [member]	'	'	'	'
Current assets	'	'	'	'
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	956,600,000	914,000,000	'	'
Affiliate receivables	13,200,000	16,100,000	'	'
Gas and natural gas liquids in storage	390,600,000	235,800,000	'	'
Commodity imbalances	93,700,000	89,700,000	'	'
Other current assets	83,900,000	88,100,000	'	'
Total current assets	1,538,000,000	1,343,700,000	'	'
Property, plant and equipment	'	'	'	'
Property, plant and equipment	10,245,400,000	8,585,200,000	'	'
Accumulated depreciation and amortization	1,595,800,000	1,440,900,000	'	'
Net property, plant and equipment	8,649,600,000	7,144,300,000	'	'
Investments and other assets	'	'	'	'
Investments in unconsolidated affiliates	826,400,000	828,600,000	'	'
Intercompany notes receivable	0	0	'	'
Goodwill and intangible assets	640,100,000	645,800,000	'	'
Other assets	27,900,000	24,400,000	'	'
Total investments and other assets	1,494,400,000	1,498,800,000	'	'
Total assets	11,682,000,000	9,986,800,000	'	'
Current liabilities	'	'	'	'
Current maturities of long-term debt	7,700,000	7,600,000	'	'
Notes payable	0	'	'	'
Accounts payable	1,202,000,000	1,058,000,000	'	'
Affiliate payables	43,900,000	75,700,000	'	'
Commodity imbalances	228,200,000	273,200,000	'	'
Accrued interest	0	0	'	'
Other current liabilities	99,600,000	79,200,000	'	'
Total current liabilities	1,581,400,000	1,493,700,000	'	'
Intercompany debt	5,934,100,000	4,833,300,000	'	'
Long-term debt, excluding current maturities	61,500,000	67,200,000	'	'
Deferred credits and other liabilities	108,000,000	121,700,000	'	'
Equity	'	'	'	'
Equity excluding noncontrolling interests in consolidated subsidiaries	3,992,400,000	3,466,100,000	'	'
Noncontrolling interests in consolidated subsidiaries	4,600,000	4,800,000	'	'
Total equity	3,997,000,000	3,470,900,000	'	'
Total liabilities and equity	11,682,000,000	9,986,800,000	'	'
Consolidating Entries [member]	'	'	'	'
Current assets	'	'	'	'
Cash and cash equivalents	0	0	0	0
Accounts receivable, net	0	0	'	'
Affiliate receivables	0	0	'	'
Gas and natural gas liquids in storage	0	0	'	'
Commodity imbalances	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	-8,355,300,000	-7,924,800,000	'	'
Intercompany notes receivable	-12,596,200,000	-9,603,900,000	'	'
Goodwill and intangible assets	0	0	'	'
Other assets	0	0	'	'
Total investments and other assets	-20,951,500,000	-17,528,700,000	'	'
Total assets	-20,951,500,000	-17,528,700,000	'	'
Current liabilities	'	'	'	'
Current maturities of long-term debt	0	0	'	'
Notes payable	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	-12,596,200,000	-9,603,900,000	'	'
Long-term debt, excluding current maturities	0	0	'	'
Deferred credits and other liabilities	0	0	'	'
Equity	'	'	'	'
Equity excluding noncontrolling interests in consolidated subsidiaries	-8,355,300,000	-7,924,800,000	'	'
Noncontrolling interests in consolidated subsidiaries	0	0	'	'
Total equity	-8,355,300,000	-7,924,800,000	'	'
Total liabilities and equity	-20,951,500,000	-17,528,700,000	'	'
Total [Member]	'	'	'	'
Current assets	'	'	'	'
Cash and cash equivalents	723,000,000	537,100,000	963,600,000	35,100,000
Accounts receivable, net	956,600,000	914,000,000	'	'
Affiliate receivables	13,200,000	16,100,000	'	'
Gas and natural gas liquids in storage	390,600,000	235,800,000	'	'
Commodity imbalances	93,700,000	89,700,000	'	'
Other current assets	83,900,000	99,000,000	'	'
Total current assets	2,261,000,000	1,891,700,000	'	'
Property, plant and equipment	'	'	'	'
Property, plant and equipment	10,245,400,000	8,585,200,000	'	'
Accumulated depreciation and amortization	1,595,800,000	1,440,900,000	'	'
Net property, plant and equipment	8,649,600,000	7,144,300,000	'	'
Investments and other assets	'	'	'	'
Investments in unconsolidated affiliates	1,201,900,000	1,221,400,000	'	'
Intercompany notes receivable	0	0	'	'
Goodwill and intangible assets	640,100,000	645,800,000	'	'
Other assets	110,700,000	56,000,000	'	'
Total investments and other assets	1,952,700,000	1,923,200,000	'	'
Total assets	12,863,300,000	10,959,200,000	'	'
Current liabilities	'	'	'	'
Current maturities of long-term debt	7,700,000	7,600,000	'	'
Notes payable	47,000,000	'	'	'
Accounts payable	1,202,000,000	1,058,000,000	'	'
Affiliate payables	43,900,000	75,700,000	'	'
Commodity imbalances	228,200,000	273,200,000	'	'
Accrued interest	88,500,000	76,700,000	'	'
Other current liabilities	99,600,000	79,200,000	'	'
Total current liabilities	1,716,900,000	1,570,400,000	'	'
Intercompany debt	0	0	'	'
Long-term debt, excluding current maturities	6,046,500,000	4,803,600,000	'	'
Deferred credits and other liabilities	108,000,000	121,700,000	'	'
Equity	'	'	'	'
Equity excluding noncontrolling interests in consolidated subsidiaries	4,987,300,000	4,458,700,000	'	'
Noncontrolling interests in consolidated subsidiaries	4,600,000	4,800,000	'	'
Total equity	4,991,900,000	4,463,500,000	'	'
Total liabilities and equity	$12,863,300,000	$10,959,200,000	'	'

SUPPLEMENTAL_CONDENSED_CONSOLI5

SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION, Cash Flows (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2012	Sep. 30, 2013	Sep. 30, 2012
Operating activities	'	'	'	'	'
Cash provided by operating activities	'	'	'	$654,118,000	$620,520,000
Investing activities	'	'	'	'	'
Capital expenditures (less allowance for equity funds used during construction)	'	-375,291,000	'	-1,373,904,000	-1,011,527,000
Acquisition	'	'	'	304,889,000	0
Contributions to unconsolidated affiliates	'	'	'	-4,558,000	-21,284,000
Distributions received from unconsolidated affiliates	'	'	'	24,891,000	25,756,000
Proceeds from sale of assets	'	'	'	641,000	1,663,000
Cash provided by (used in) investing activities	'	'	'	-1,657,819,000	-1,005,392,000
Financing activities	'	'	'	'	'
Cash distributions: general and limited partners	'	'	'	-669,981,000	-550,978,000
Cash distributions: noncontrolling interests	'	'	'	-442,000	-636,000
Borrowing of notes payable, net	'	'	'	47,000,000	0
Issuance of long-term debt, net of discounts	'	'	'	1,247,822,000	1,295,036,000
Long-term debt financing costs	'	'	'	-10,217,000	-9,635,000
Repayments of long-term debt	'	'	'	-5,738,000	-358,948,000
Issuance of common units, net of issuance costs	'	'	'	569,246,000	919,521,000
Contribution from general partner	11,600,000	'	19,000,000	11,967,000	19,069,000
Cash provided by financing activities	'	'	'	1,189,657,000	1,313,429,000
Change in cash and cash equivalents	'	'	'	185,956,000	928,557,000
Cash and cash equivalents at beginning of period	'	'	35,091,000	537,074,000	35,091,000
Cash and cash equivalents at end of period	723,030,000	963,648,000	'	723,030,000	963,648,000
Parent [member]	'	'	'	'	'
Operating activities	'	'	'	'	'
Cash provided by operating activities	'	'	'	641,500,000	551,000,000
Investing activities	'	'	'	'	'
Capital expenditures (less allowance for equity funds used during construction)	'	'	'	0	0
Acquisition	'	'	'	0	'
Contributions to unconsolidated affiliates	'	'	'	0	0
Distributions received from unconsolidated affiliates	'	'	'	0	0
Proceeds from sale of assets	'	'	'	0	0
Cash provided by (used in) investing activities	'	'	'	0	0
Financing activities	'	'	'	'	'
Cash distributions: general and limited partners	'	'	'	-670,000,000	-551,000,000
Cash distributions: noncontrolling interests	'	'	'	0	0
Borrowing of notes payable, net	'	'	'	47,000,000	'
Issuance of long-term debt, net of discounts	'	'	'	1,247,800,000	1,295,000,000
Long-term debt financing costs	'	'	'	-10,200,000	-9,700,000
Intercompany borrowings (advances), net	'	'	'	-1,837,200,000	-1,873,900,000
Repayments of long-term debt	'	'	'	0	-350,000,000
Issuance of common units, net of issuance costs	'	'	'	569,200,000	919,500,000
Contribution from general partner	'	'	'	11,900,000	19,100,000
Cash provided by financing activities	'	'	'	-641,500,000	-551,000,000
Change in cash and cash equivalents	'	'	'	0	0
Cash and cash equivalents at beginning of period	'	'	0	0	0
Cash and cash equivalents at end of period	0	0	'	0	0
Guarantor Subsidiary [member]	'	'	'	'	'
Operating activities	'	'	'	'	'
Cash provided by operating activities	'	'	'	48,100,000	54,500,000
Investing activities	'	'	'	'	'
Capital expenditures (less allowance for equity funds used during construction)	'	'	'	0	0
Acquisition	'	'	'	0	'
Contributions to unconsolidated affiliates	'	'	'	0	0
Distributions received from unconsolidated affiliates	'	'	'	17,300,000	16,800,000
Proceeds from sale of assets	'	'	'	0	0
Cash provided by (used in) investing activities	'	'	'	17,300,000	16,800,000
Financing activities	'	'	'	'	'
Cash distributions: general and limited partners	'	'	'	-670,000,000	-551,000,000
Cash distributions: noncontrolling interests	'	'	'	0	0
Borrowing of notes payable, net	'	'	'	0	'
Issuance of long-term debt, net of discounts	'	'	'	0	0
Long-term debt financing costs	'	'	'	0	0
Intercompany borrowings (advances), net	'	'	'	790,500,000	1,408,200,000
Repayments of long-term debt	'	'	'	0	0
Issuance of common units, net of issuance costs	'	'	'	0	0
Contribution from general partner	'	'	'	0	0
Cash provided by financing activities	'	'	'	120,500,000	857,200,000
Change in cash and cash equivalents	'	'	'	185,900,000	928,500,000
Cash and cash equivalents at beginning of period	'	'	35,100,000	537,100,000	35,100,000
Cash and cash equivalents at end of period	723,000,000	963,600,000	'	723,000,000	963,600,000
Combined Non-Guarantor Subsidiaries [member]	'	'	'	'	'
Operating activities	'	'	'	'	'
Cash provided by operating activities	'	'	'	634,500,000	566,000,000
Investing activities	'	'	'	'	'
Capital expenditures (less allowance for equity funds used during construction)	'	'	'	-1,373,900,000	-1,011,500,000
Acquisition	'	'	'	-304,900,000	'
Contributions to unconsolidated affiliates	'	'	'	-4,600,000	-21,300,000
Distributions received from unconsolidated affiliates	'	'	'	7,600,000	8,900,000
Proceeds from sale of assets	'	'	'	700,000	1,700,000
Cash provided by (used in) investing activities	'	'	'	-1,675,100,000	-1,022,200,000
Financing activities	'	'	'	'	'
Cash distributions: general and limited partners	'	'	'	0	0
Cash distributions: noncontrolling interests	'	'	'	-400,000	-600,000
Borrowing of notes payable, net	'	'	'	0	'
Issuance of long-term debt, net of discounts	'	'	'	0	0
Long-term debt financing costs	'	'	'	0	0
Intercompany borrowings (advances), net	'	'	'	1,046,700,000	465,700,000
Repayments of long-term debt	'	'	'	-5,700,000	-8,900,000
Issuance of common units, net of issuance costs	'	'	'	0	0
Contribution from general partner	'	'	'	0	0
Cash provided by financing activities	'	'	'	1,040,600,000	456,200,000
Change in cash and cash equivalents	'	'	'	0	0
Cash and cash equivalents at beginning of period	'	'	0	0	0
Cash and cash equivalents at end of period	0	0	'	0	0
Consolidating Entries [member]	'	'	'	'	'
Operating activities	'	'	'	'	'
Cash provided by operating activities	'	'	'	-670,000,000	-551,000,000
Investing activities	'	'	'	'	'
Capital expenditures (less allowance for equity funds used during construction)	'	'	'	0	0
Acquisition	'	'	'	0	'
Contributions to unconsolidated affiliates	'	'	'	0	0
Distributions received from unconsolidated affiliates	'	'	'	0	0
Proceeds from sale of assets	'	'	'	0	0
Cash provided by (used in) investing activities	'	'	'	0	0
Financing activities	'	'	'	'	'
Cash distributions: general and limited partners	'	'	'	670,000,000	551,000,000
Cash distributions: noncontrolling interests	'	'	'	0	0
Borrowing of notes payable, net	'	'	'	0	'
Issuance of long-term debt, net of discounts	'	'	'	0	0
Long-term debt financing costs	'	'	'	0	0
Intercompany borrowings (advances), net	'	'	'	0	0
Repayments of long-term debt	'	'	'	0	0
Issuance of common units, net of issuance costs	'	'	'	0	0
Contribution from general partner	'	'	'	0	0
Cash provided by financing activities	'	'	'	670,000,000	551,000,000
Change in cash and cash equivalents	'	'	'	0	0
Cash and cash equivalents at beginning of period	'	'	0	0	0
Cash and cash equivalents at end of period	0	0	'	0	0
Total [Member]	'	'	'	'	'
Operating activities	'	'	'	'	'
Cash provided by operating activities	'	'	'	654,100,000	620,500,000
Investing activities	'	'	'	'	'
Capital expenditures (less allowance for equity funds used during construction)	'	'	'	-1,373,900,000	-1,011,500,000
Acquisition	'	'	'	-304,900,000	'
Contributions to unconsolidated affiliates	'	'	'	-4,600,000	-21,300,000
Distributions received from unconsolidated affiliates	'	'	'	24,900,000	25,700,000
Proceeds from sale of assets	'	'	'	700,000	1,700,000
Cash provided by (used in) investing activities	'	'	'	-1,657,800,000	-1,005,400,000
Financing activities	'	'	'	'	'
Cash distributions: general and limited partners	'	'	'	-670,000,000	-551,000,000
Cash distributions: noncontrolling interests	'	'	'	-400,000	-600,000
Borrowing of notes payable, net	'	'	'	47,000,000	'
Issuance of long-term debt, net of discounts	'	'	'	1,247,800,000	1,295,000,000
Long-term debt financing costs	'	'	'	-10,200,000	-9,700,000
Intercompany borrowings (advances), net	'	'	'	0	0
Repayments of long-term debt	'	'	'	-5,700,000	-358,900,000
Issuance of common units, net of issuance costs	'	'	'	569,200,000	919,500,000
Contribution from general partner	'	'	'	11,900,000	19,100,000
Cash provided by financing activities	'	'	'	1,189,600,000	1,313,400,000
Change in cash and cash equivalents	'	'	'	185,900,000	928,500,000
Cash and cash equivalents at beginning of period	'	'	35,100,000	537,100,000	35,100,000
Cash and cash equivalents at end of period	$723,000,000	$963,600,000	'	$723,000,000	$963,600,000