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

Document_And_Entity_Informatio

Document And Entity Information (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 19, 2015	Jun. 30, 2014
Document Information [Line Items]
Entity Registrant Name	ONEOK INC /NEW/
Entity Central Index Key	1039684
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$13.90
Entity Common Stock, Shares Outstanding		208,400,547
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14

CONSOLIDATED_STATEMENTS_OF_INC

CONSOLIDATED STATEMENTS OF INCOME (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Commodity Sales	$10,724,981	$10,549,157	$9,010,151
Services	1,470,110	1,322,722	1,173,970
Total revenues	12,195,091	11,871,879	10,184,121
Cost of sales and fuel	10,088,548	10,222,213	8,540,319
Net margin	2,106,543	1,649,666	1,643,802
Operating expenses
Operations and maintenance	599,143	479,165	437,650
Depreciation and amortization	294,684	239,343	205,334
General taxes	75,744	62,421	54,075
Total operating expenses	969,571	780,929	697,059
Gain (loss) on sale of assets	6,599	11,881	6,736
Operating income	1,143,571	880,618	953,479
Equity earnings from investments (Note P)	41,003	110,517	123,024
Allowance for equity funds used during construction	14,937	30,522	13,648
Other income	5,598	18,158	8,639
Other expense	-29,073	-13,999	-2,646
Interest Expense (net of capitalized interest of $54,813, $56,506 and $40,482, respectively)	-356,163	-270,646	-237,638
Income before income taxes	819,873	755,170	858,506
Income taxes (Note O)	-151,158	-166,080	-180,758
Income from continuing operations	668,715	589,090	677,748
Income from discontinued operations, net of tax (Note B)	-5,607	-12,129	52,265
Gain on sale of discontinued operations, net of tax (Note B)	0	0	13,517
Net income	663,108	576,961	743,530
Less: Net income attributable to noncontrolling interests	349,001	310,428	382,911
Net income attributable to ONEOK	314,107	266,533	360,619
Amounts attributable to ONEOK:
Income from continuing operations	319,714	278,662	294,837
Income (loss) from discontinued operations	-5,607	-12,129	65,782
Net Income	$314,107	$266,533	$360,619
Basic earnings per share:
Income from continuing operations (Note L)	$1.53	$1.35	$1.43
Income (loss) from discontinued operations	($0.03)	($0.06)	$0.32
Net Income	$1.50	$1.29	$1.75
Diluted earnings per share:
Income from continuing operations (Note L)	$1.52	$1.33	$1.40
Income (loss) from discontinued operations	($0.03)	($0.06)	$0.31
Net Income	$1.49	$1.27	$1.71
Average shares (thousands)
Basic	209,391	206,044	206,140
Diluted	210,427	209,695	210,710
Dividends declared per share of common stock	$2.13	$1.48	$1.27

CONSOLIDATED_STATEMENTS_OF_INC1

CONSOLIDATED STATEMENTS OF INCOME (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Interest Costs, Capitalized During Period	$54,813	$56,506	$40,482

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$663,108	$576,961	$743,530
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on energy marketing and risk management assets/liabilities, net of tax of $10,029, $(5,574) and $(10,061), respectively	-58,307	25,609	22,826
Realized (gains) losses in net income, net of tax of $(14,098), $(1,905) and $10,327, respectively	41,723	7,926	-49,499
Unrealized holding gains (losses) on available-for-sale securities, net of tax of $(106), $112 and $(30), respectively	98	-177	47
Change in pension and postretirement benefit plan liability, net of tax of $15,781, $(52,436) and $6,977, respectively	-23,672	83,126	-11,061
Total other comprehensive income (loss), net of tax	-40,158	116,484	-37,687
Comprehensive income	622,950	693,445	705,843
Less: Comprehensive income attributable to noncontrolling interests	326,598	332,101	355,901
Comprehensive income attributable to ONEOK	$296,352	$361,344	$349,942

CONSOLIDATED_STATEMENTS_OF_COM1

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Unrealized gain (losses) on energy marketing and risk management assets/liabilities, tax	$10,029	($5,574)	($10,061)
Realized (gains) losses in net income, tax	-14,098	-1,905	10,327
Unrealized holding gains (losses) on available-for-sale securities, tax	-106	112	-30
Change in pension and postretirement benefit plan liability, tax	$15,781	($52,436)	$6,977

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets
Cash and cash equivalents	$172,812	$145,565
Accounts receivable, net	745,494	1,109,510
Natural gas and natural gas liquids in storage	134,134	188,286
Commodity imbalances	64,788	80,481
Other current assets	173,299	133,010
Assets of discontinued operations (Note B)	16,717	747,872
Total current assets	1,307,244	2,404,724
Property, plant and equipment
Property, plant and equipment	13,602,647	10,970,256
Accumulated depreciation and amortization	1,940,210	1,738,302
Net property, plant and equipment (Note F)	11,662,437	9,231,954
Investments and other assets
Investments in unconsolidated affiliates (Note P)	1,132,653	1,229,838
Goodwill and intangible assets (Note G)	1,014,740	1,024,562
Other assets	167,466	224,353
Assets of discontinued operations (Note B)	20,020	3,626,050
Total investments and other assets	2,334,879	6,104,803
Total assets	15,304,560	17,741,481
Current liabilities
Current maturities of long-term debt (Note I)	10,650	10,650
Notes payable (Note H)	1,055,296	564,462
Accounts payable	891,413	1,273,102
Commodity imbalances	104,650	213,577
Other current liabilities	285,435	212,851
Liabilities of discontinued operations (Note B)	44,901	455,688
Total current liabilities	2,392,345	2,730,330
Long-term debt, excluding current maturities (Note I)	7,192,929	7,753,657
Deferred credits and other liabilities
Deferred income taxes (Note O)	1,395,222	1,146,562
Other deferred credits	281,757	217,522
Liabilities of discontinued operations (Note B)	36,424	1,048,230
Total deferred credits and other liabilities	1,713,403	2,412,314
Commitments and contingencies (Note R)
ONEOK shareholders' equity:
Common stock, $0.01 par value: authorized 600,000,000 shares; issued 245,811,180 shares and outstanding 208,322,247 shares at December 31, 2014; issued 245,811,180 shares and outstanding 206,618,877 shares at December 31, 2013	2,458	2,458
Paid-in capital	1,541,583	1,433,600
Accumulated other comprehensive loss (Note K)	-136,353	-121,987
Retained earnings	138,128	2,020,815
Treasury stock, at cost: 37,488,933 shares at December 31, 2014 and 39,192,303 shares at December 31, 2013	-953,701	-997,035
Total ONEOK shareholders' equity	592,115	2,337,851
Noncontrolling interests in consolidated subsidiaries	3,413,768	2,507,329
Total equity	4,005,883	4,845,180
Total liabilities and equity	$15,304,560	$17,741,481

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS Parenthetical (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Common stock, shares, par value (in dollars per share)	$0.01	$0.01
Common stock, shares, authorized (in shares)	600,000,000	600,000,000
Common stock, shares, issued (in shares)	245,811,180	245,811,180
Common stock, shares, outstanding (in shares)	208,322,247	206,618,877
Treasury stock, shares (in shares)	37,488,933	39,192,203

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Activities
Net income	$663,108	$576,961	$743,530
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	306,038	384,377	335,852
Charges attributable to exit activities	1,739	138,559	0
Impairment of goodwill	0	0	10,255
Gain on sale of discontinued operations	0	0	-13,517
Equity earnings from investments	-41,003	-110,517	-123,024
Distributions received from unconsolidated affiliates	117,912	106,364	120,442
Deferred income taxes	156,728	151,515	229,398
Share-based compensation expense	26,226	46,194	36,692
Pension and other postretirement benefit expense, net of contributions	18,093	56,600	-57,073
Allowance for equity funds used during construction	-14,937	-30,522	-13,648
Loss (gain) on sale of assets	-6,599	-11,881	-6,736
Other	0	-5,656	27,982
Changes in assets and liabilities, net of acquisitions:
Accounts receivable	381,513	-189,809	-14,774
Natural gas and natural gas liquids in storage	160,860	99,937	33,343
Accounts payable	-417,993	165,076	-30,981
Commodity imbalances, net	-90,354	-52,233	43,471
Settlement of exit activities liabilities	-51,757	-17,756	0
Energy marketing and risk management assets and liabilities	59,539	25,072	-174,953
Other assets and liabilities, net	16,497	-37,514	-162,264
Cash provided by operating activities	1,285,610	1,294,767	983,995
Investing Activities
Capital expenditures (less allowance for equity funds used during construction)	-1,779,150	-2,256,585	-1,866,153
Cash paid for acquisitions, net of cash acquired	-814,934	-394,889	0
Proceeds from sale of discontinued operations, net of cash sold	0	0	32,946
Contributions to unconsolidated affiliates	-1,063	-35,308	-30,768
Distributions received from unconsolidated affiliates	21,107	31,134	35,299
Proceeds from sale of assets	7,817	13,617	12,240
Other	0	0	2,237
Cash used in investing activities	-2,566,223	-2,642,031	-1,814,199
Financing Activities
Borrowing (repayment) of notes payable, net	490,834	-252,708	-24,812
Issuance of ONE Gas debt, net of discounts	1,199,994	0	0
Issuance of long-term debt, net of discounts	0	1,247,822	1,994,693
ONE Gas long-term debt financing costs	-9,663	0	0
Long-term debt financing costs	0	-10,246	-15,036
Repayment of long-term debt	-557,679	-7,868	-361,464
Repurchase of common stock	0	0	-150,000
Issuance of common stock	19,150	20,602	15,969
Issuance of common units, net of issuance costs	1,113,139	583,929	459,587
Dividends paid	-443,817	-304,742	-261,969
Cash of ONE Gas at separation	-60,000	0	0
Distributions to noncontrolling interests	-447,459	-374,142	-324,906
Excess tax benefit from stock-based awards	0	10,312	6,948
Cash provided by financing activities	1,304,499	912,959	1,339,010
Change in cash and cash equivalents	23,886	-434,305	508,806
Change in cash and cash equivalents included in discontinued operations	3,361	2,848	11,532
Change in cash and cash equivalents from continuing operations	27,247	-431,457	520,338
Cash and cash equivalents at beginning of period	145,565	577,022	56,684
Cash and cash equivalents at end of period	172,812	145,565	577,022
Supplemental cash flow information:
Cash paid for interest, net of amounts capitalized	340,144	294,240	439,398
Cash paid (refunds received) for income taxes	($11,881)	($16,640)	$872

CONSOLIDATED_STATEMENT_OF_CHAN

CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (USD $)	Total	Common Stock [Member]	Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interests in Consolidated Subsidiaries [Member]
In Thousands, except Share data
Shareholders' equity, beginning balance at Dec. 31, 2011	$3,799,732	$2,458	$1,417,185	($206,121)	$1,960,374	($935,323)	$1,561,159
Common stock issued, beginning balance (in shares) at Dec. 31, 2011		245,809,848
Net income	743,530	0	0	0	360,619	0	382,911
Other comprehensive income (loss) (Note K)	-37,687	0	0	-10,677	0	0	-27,010
Repurchase of common stock	-150,000	0	0	0	0	-150,000	0
Common stock issued (in shares)		1,332
Common stock issued	22,146	0	-23,404	0	0	45,550	0
Common stock dividends - $1.27, $1.48, and $2.125 per share (Note J)	-261,969	0	0	0	-261,969	0	0
Issuance of common units of ONEOK Partners (Note Q)	459,587	0	-51,100	0	0	0	510,687
Distributions to noncontrolling interests	-324,906	0	0	0	0	0	-324,906
Other	-17,983	0	-17,983	0	0	0	0
Shareholders' equity, ending balance at Dec. 31, 2012	4,232,450	2,458	1,324,698	-216,798	2,059,024	-1,039,773	2,102,841
Common stock issued, ending balance (in shares) at Dec. 31, 2012		245,811,180
Net income	576,961	0	0	0	266,533	0	310,428
Other comprehensive income (loss) (Note K)	116,484	0	0	94,811	0	0	21,673
Common stock issued (in shares)		0
Common stock issued	26,189	0	-16,549	0	0	42,738	0
Common stock dividends - $1.27, $1.48, and $2.125 per share (Note J)	-304,742	0	0	0	-304,742	0	0
Issuance of common units of ONEOK Partners (Note Q)	533,824	0	87,295	0	0	0	446,529
Distributions to noncontrolling interests	-374,142	0	0	0	0	0	-374,142
Other	38,156	0	38,156	0	0	0	0
Shareholders' equity, ending balance at Dec. 31, 2013	4,845,180	2,458	1,433,600	-121,987	2,020,815	-997,035	2,507,329
Common stock issued, ending balance (in shares) at Dec. 31, 2013		245,811,180
Net income	663,108	0	0	0	314,107	0	349,001
Other comprehensive income (loss) (Note K)	-40,158	0	0	-17,755	0	0	-22,403
Common stock issued (in shares)		0
Common stock issued	25,027	0	-18,307	0	0	43,334	0
Common stock dividends - $1.27, $1.48, and $2.125 per share (Note J)	-443,817	0	0	0	-443,817	0	0
Issuance of common units of ONEOK Partners (Note Q)	1,020,530	0	156,143	0	0	0	864,387
Distributions to noncontrolling interests	-447,459	0	0	0	0	0	-447,459
West Texas LPG noncontrolling interest (Note C)	162,913	0	0	0	0	0	162,913
Other	-29,853	0	-29,853	0	0	0	0
Stockholders' Equity Note, Spinoff Transaction	-1,749,588	0	0	3,389	-1,752,977	0	0
Shareholders' equity, ending balance at Dec. 31, 2014	$4,005,883	$2,458	$1,541,583	($136,353)	$138,128	($953,701)	$3,413,768
Common stock issued, ending balance (in shares) at Dec. 31, 2014		245,811,180

CONSOLIDATED_STATEMENT_OF_CHAN1

CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Stockholders' Equity [Abstract]
Dividends declared per share of common stock	$2.13	$1.48	$1.27

SUMMARY_OF_SIGNIFICANT_ACCOUNT

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	A.	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Organization and Nature of Operations - We are the sole general partner and owned 37.8 percent of ONEOK Partners, L.P. (NYSE: OKS), one of the largest publicly traded master limited partnerships, at December 31, 2014. We are a corporation incorporated under the laws of the state of Oklahoma, and our common stock is listed on the NYSE under the trading symbol “OKE.”
	On January 31, 2014, we completed the separation of our former natural gas distribution business into a stand-alone publicly traded company, ONE Gas. In addition, we completed the wind down of our former energy services business on March 31, 2014. Following the separation of the natural gas distribution business and the wind down of our energy services business, our primary source of income and cash flows is generated from our investment in ONEOK Partners. See Note B for additional discussion of the separation of the natural gas distribution business and the wind down of the energy services business.
	For all periods presented, the accompanying consolidated financial statements and notes reflect the results of operations and financial position of our former natural gas distribution and energy services businesses as discontinued operations. Unless indicated otherwise, the information in the Notes to the Consolidated Financial Statements relates to our continuing operations.
	Following the separation of our natural gas distribution business into ONE Gas and wind down of our energy services business, our chief operating decision maker reviews the financial performance of each of the three businesses of ONEOK Partners on a regular basis to assess the performance of, and allocate resources to, ONEOK Partners. As a result, our reportable segments have changed to reflect the three business segments of ONEOK Partners. We have reflected the change in reporting segments for all periods presented. See Note S for additional information.
	ONEOK Partners is a publicly traded master limited partnership involved in the gathering, processing, storage and transportation of natural gas in the United States.  In addition, ONEOK Partners owns one of the nation’s premier natural gas liquids systems, connecting NGL supply in the Mid-Continent and Rocky Mountain regions with key market centers.
	The Natural Gas Gathering and Processing segment gathers and/or processes natural gas in two producing basins in the Rocky Mountain region: the Williston Basin, which spans portions of Montana and North Dakota and includes the oil-producing, NGL-rich Bakken Shale and Three Forks formations; and the Powder River Basin of Wyoming, which includes the NGL-rich Frontier, Turner, Sussex and Niobrara Shale formations. The natural gas ONEOK Partners gathers from wells that supply its Sage Creek plant contains NGL-rich natural gas from the Niobrara Shale area of the Powder River Basin. Some of the natural gas it gathers from the Powder River Basin of Wyoming is coal-bed methane, or dry natural gas, that does not require processing or NGL extraction in order to be marketable; dry natural gas is gathered, compressed and delivered into a downstream pipeline or marketed for a fee. ONEOK Partners also gathers and processes natural gas in the Mid-Continent region, which includes the NGL-rich Cana-Woodford Shale, Woodford Shale, Stack, SCOOP, Springer Shale and the Mississippian Lime formation of Oklahoma and Kansas, and the Hugoton and Central Kansas Uplift Basins of Kansas.
	The Natural Gas Liquids segment consists of facilities that gather, fractionate and treat NGLs and store NGL products primarily in Oklahoma, Kansas, Texas, New Mexico and the Rocky Mountain region where it provides nondiscretionary services to producers for NGLs. The natural gas liquids business owns or has an ownership interest in FERC-regulated natural gas liquids gathering and distribution pipelines in Oklahoma, Kansas, Texas, New Mexico, Montana, North Dakota, Wyoming and Colorado, and terminal and storage facilities in Missouri, Nebraska, Iowa and Illinois.  It also owns FERC-regulated natural gas liquids distribution and refined petroleum products pipelines in Kansas, Missouri, Nebraska, Iowa, Illinois and Indiana that connect its Mid-Continent assets with Midwest markets, including Chicago, Illinois.  ONEOK Partners’ natural gas liquids business also owns and operates truck- and rail-loading and -unloading facilities that interconnect with its NGL fractionation and pipeline assets.
	The Natural Gas Pipeline segment operates interstate and intrastate natural gas transmission pipelines and natural gas storage facilities.  ONEOK Partners’ FERC-regulated interstate assets transport natural gas through pipelines in North Dakota, Minnesota, Wisconsin, Illinois, Indiana, Kentucky, Tennessee, Oklahoma, Texas and New Mexico.  ONEOK Partners’ intrastate natural gas pipeline assets are located in Oklahoma, Texas and Kansas, and have access to major natural gas producing areas in those states, including the Cana-Woodford Shale, Woodford Shale, Springer Shale, Granite Wash, Stack, SCOOP and Mississippian Lime areas.  ONEOK Partners owns underground natural gas storage facilities in Oklahoma and Texas, which are connected to its intrastate natural gas pipeline assets, as well as underground natural gas storage facilities in Kansas.
	Our former natural gas distribution business provides natural gas distribution services to more than 2 million customers in Oklahoma, Kansas and Texas through Oklahoma Natural Gas, Kansas Gas Service and Texas Gas Service. The natural gas utilities serve residential, commercial, industrial and transportation customers in all three states.  In addition, the natural gas distribution companies serve wholesale and public authority customers.
	Our former energy services business was a provider of natural gas supply and risk-management services. We used a network of leased storage and transportation capacity to supply natural gas to our customers. Our customers were primarily local distribution companies, electric utilities and industrial end users. Our customers’ natural gas needs varied with seasonal changes in weather and were therefore somewhat unpredictable.
	Consolidation - Our consolidated financial statements include the accounts of ONEOK and our subsidiaries over which we have control or are the primary beneficiary. We have recorded noncontrolling interests in consolidated subsidiaries on our Consolidated Balance Sheets to recognize the portion of ONEOK Partners that we do not own. We reflected our ownership interest in ONEOK Partners’ accumulated other comprehensive income (loss) in our consolidated accumulated other comprehensive income (loss). The remaining portion is reflected as an adjustment to noncontrolling interests in consolidated subsidiaries.
	ONEOK Partners provides natural gas sales and transportation and storage services to our former natural gas distribution business. Prior to the completion of the energy services wind down, ONEOK Partners provided natural gas sales and transportation and storage services to our former energy services business. While these transactions were eliminated in consolidation in previous periods, they are reflected now as affiliate transactions and not eliminated in consolidation for all periods presented as these transactions have continued with third parties. See Note B for additional information.
	All other significant intercompany balances and transactions have been eliminated in consolidation.
	Investments in unconsolidated affiliates are accounted for using the equity method if we have the ability to exercise significant influence over operating and financial policies of our investee. Under this method, an investment is carried at its acquisition cost and adjusted each period for contributions made, distributions received and our share of the investee’s comprehensive income. For the investments we account for under the equity method, the premium or excess cost over underlying fair value of net assets is referred to as equity method goodwill. Impairment of equity investments is recorded when the impairments are other than temporary. These amounts are recorded as investments in unconsolidated affiliates on our accompanying Consolidated Balance Sheets.  See Note P for disclosures of our unconsolidated affiliates.
	Distributions paid to us from our unconsolidated affiliates are classified as operating activities on our Consolidated Statements of Cash Flows until the cumulative distributions exceed our proportionate share of income from the unconsolidated affiliate since the date of our initial investment.  The amount of cumulative distributions paid to us that exceeds our cumulative proportionate share of income in each period represents a return of investment and is classified as an investing activity on our Consolidated Statements of Cash Flows.
	Use of Estimates - The preparation of our consolidated financial statements and related disclosures in accordance with GAAP requires us to make estimates and assumptions with respect to values or conditions that cannot be known with certainty that affect the reported amount of assets and liabilities, and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements. These estimates and assumptions also affect the reported amounts of revenue and expenses during the reporting period. Items that may be estimated include, but are not limited to, the economic useful life of assets, fair value of assets, liabilities and equity method investments, obligations under employee benefit plans, provisions for uncollectible accounts receivable, unbilled revenues and cost of goods sold, expenses for services received but which no invoice has been received, provision for income taxes, including any deferred tax valuation allowances, the results of litigation and various other recorded or disclosed amounts.
	We evaluate these estimates on an ongoing basis using historical experience, consultation with experts and other methods we consider reasonable based on the particular circumstances. Nevertheless, actual results may differ significantly from the estimates. Any effects on our financial position or results of operations from revisions to these estimates are recorded in the period when the facts that give rise to the revision become known.
	Fair Value Measurements - We define fair value as the price that would be received from the sale of an asset or the transfer of a liability in an orderly transaction between market participants at the measurement date. We use market and income approaches to determine the fair value of our assets and liabilities and consider the markets in which the transactions are executed. We measure the fair value of a group of financial assets and liabilities consistent with how a market participant would price the net risk exposure at the measurement date.
	While many of the contracts in ONEOK Partners’ portfolio are executed in liquid markets where price transparency exists, some contracts are executed in markets for which market prices may exist, but the market may be relatively inactive. This results in limited price transparency that requires management’s judgment and assumptions to estimate fair values. For certain transactions, we utilize modeling techniques using NYMEX-settled pricing data and implied forward LIBOR curves. Inputs into our fair value estimates include commodity-exchange prices, over-the-counter quotes, historical correlations of pricing data and LIBOR and other liquid money-market instrument rates. We also utilize internally developed basis curves that incorporate observable and unobservable market data. We validate our valuation inputs with third-party information and settlement prices from other sources, where available.
	In addition, as prescribed by the income approach, we compute the fair value of our derivative portfolio by discounting the projected future cash flows from our derivative assets and liabilities to present value using interest-rate yields to calculate present-value discount factors derived from LIBOR, Eurodollar futures and interest-rate swaps. We also take into consideration the potential impact on market prices of liquidating positions in an orderly manner over a reasonable period of time under current market conditions. We consider current market data in evaluating counterparties’, as well as our own, nonperformance risk, net of collateral, by using specific and sector bond yields and monitoring the credit default swap markets. Although we use our best estimates to determine the fair value of the derivative contracts we have executed, the ultimate market prices realized could differ from our estimates, and the differences could be material.
	The fair value of our forward-starting interest-rate swaps are determined using financial models that incorporate the implied forward LIBOR yield curve for the same period as the future interest swap settlements.
	Fair Value Hierarchy - At each balance sheet date, we utilize a fair value hierarchy to classify fair value amounts recognized or disclosed in our financial statements based on the observability of inputs used to estimate such fair value.  The levels of the hierarchy are described below:
	•	Level 1 - fair value measurements are based on unadjusted quoted prices for identical securities in active markets including NYMEX-settled prices. These balances are comprised predominantly of exchange-traded derivative contracts for natural gas and crude oil.
	•	Level 2 - fair value measurements are based on significant observable pricing inputs, such as NYMEX-settled prices for natural gas and crude oil and financial models that utilize implied forward LIBOR yield curves for interest-rate swaps.
	•	Level 3 - fair value measurements are based on inputs that may include one or more unobservable inputs, including internally developed basis curves that incorporate observable and unobservable market data, NGL price curves from broker quotes, market volatilities derived from the most recent NYMEX close spot prices and forward LIBOR curves, and adjustments for the credit risk of our counterparties. We corroborate the data on which our fair value estimates are based using our market knowledge of recent transactions, analysis of historical correlations and validation with independent broker quotes. These balances categorized as Level 3 are comprised of derivatives for natural gas and NGLs. We do not believe that our Level 3 fair value estimates have a material impact on our results of operations, as the majority of our derivatives are accounted for as hedges for which ineffectiveness is not material.
	Determining the appropriate classification of our fair value measurements within the fair value hierarchy requires management’s judgment regarding the degree to which market data is observable or corroborated by observable market data. We categorize derivatives for which fair value is determined using multiple inputs within a single level, based on the lowest level input that is significant to the fair value measurement in its entirety.
	See Note D for discussion of our fair value measurements.
	Cash and Cash Equivalents - Cash equivalents consist of highly liquid investments, which are readily convertible into cash and have original maturities of three months or less.
	Revenue Recognition - Our reportable segments recognize revenue when services are rendered or product is delivered. The Natural Gas Gathering and Processing segment records revenues when gas is processed in or transported through its facilities. The Natural Gas Liquids segment records revenues based upon contracted services and actual volumes exchanged or stored under service agreements in the period services are provided. Revenues for the Natural Gas Pipelines segment and a portion of the Natural Gas Liquids segment is recognized based upon contracted capacity and contracted volumes transported and stored under service agreements in the period services are provided.
	Our former natural gas distribution business’s major industrial and commercial natural gas distribution customers were invoiced at the end of each month. All natural gas distribution residential customers and some commercial customers were invoiced on a cyclical basis throughout the month, and the utilities accrued unbilled revenues at the end of each month. Revenues from our former natural gas distribution business are included in discontinued operations.
	Our revenues from sales to our former energy services business’s wholesale customers were accrued in the month of physical delivery based on contracted sales price and estimated volumes. Demand payments received for requirements contracts were recognized in the period in which the service was provided. Our fixed-price physical sales were accounted for as derivatives and were recorded at fair value. Revenues from our former energy services business are included in discontinued operations.
	Accounts Receivable - Accounts receivable represent valid claims against nonaffiliated customers for products sold or services rendered, net of allowances for doubtful accounts. We assess the creditworthiness of our counterparties on an ongoing basis and require security, including prepayments and other forms of collateral, when appropriate. Outstanding customer receivables are reviewed regularly for possible nonpayment indicators and allowances for doubtful accounts are recorded based upon management’s estimate of collectability at each balance sheet date. At December 31, 2014 and 2013, the allowance for doubtful accounts was not material.
	Inventory - The values of current natural gas and NGLs in storage are determined using the lower of weighted-average cost or market method.  Noncurrent natural gas and NGLs are classified as property and valued at cost.  Materials and supplies are valued at average cost.
	Commodity Imbalances - Commodity imbalances represent amounts payable or receivable for NGL exchange contracts and natural gas pipeline imbalances and are valued at market prices. Under the majority of our NGL exchange agreements, we physically receive volumes of unfractionated NGLs, including the risk of loss and legal title to such volumes, from the exchange counterparty. In turn, we deliver NGL products back to the customer and charge them gathering and fractionation fees. To the extent that the volumes we receive under such agreements differ from those we deliver, we record a net exchange receivable or payable position with the counterparties. These net exchange receivables and payables are settled with movements of NGL products rather than with cash. Natural gas pipeline imbalances are settled in cash or in-kind, subject to the terms of the pipelines’ tariffs or by agreement.
	Derivatives and Risk Management - We and ONEOK Partners utilize derivatives to reduce our market risk exposure to commodity price and interest-rate fluctuations and to achieve more predictable cash flows.  We and ONEOK Partners record all derivative instruments at fair value, with the exception of normal purchases and normal sales transactions that are expected to result in physical delivery.  Commodity price and interest-rate volatility may have a significant impact on the fair value of derivative instruments as of a given date.
	The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and, if so, the reason for holding it.  The table below summarizes the various ways in which we account for our derivative instruments and the impact on our consolidated financial statements:
			Recognition and Measurement
	Accounting Treatment		Balance Sheet		Income Statement
	Normal purchases and	-	Fair value not recorded	-	Change in fair value not recognized in earnings
	normal sales
	Mark-to-market	-	Recorded at fair value	-	Change in fair value recognized in earnings
	Cash flow hedge	-	Recorded at fair value	-	Ineffective portion of the gain or loss on the
					derivative instrument is recognized in earnings
		-	Effective portion of the gain or loss on the	-	Effective portion of the gain or loss on the
			derivative instrument is reported initially as a		derivative instrument is reclassified out of
			component of accumulated other		accumulated other comprehensive income (loss)
			comprehensive income (loss)		into earnings when the forecasted transaction
					affects earnings
	Fair value hedge	-	Recorded at fair value	-	The gain or loss on the derivative instrument is
					recognized in earnings
		-	Change in fair value of the hedged item is	-	Change in fair value of the hedged item is
			recorded as an adjustment to book value		recognized in earnings
	To reduce our exposure to fluctuations in natural gas, NGLs and condensate prices, we and ONEOK Partners periodically enter into futures, forward sales, options or swap transactions in order to hedge anticipated purchases and sales of natural gas, NGLs and condensate.  Interest-rate swaps are used from time to time to manage interest-rate risk.  Under certain conditions, we and ONEOK Partners designate these derivative instruments as a hedge of exposure to changes in cash flow.  We and ONEOK Partners formally document all relationships between hedging instruments and hedged items, as well as risk-management objectives and strategies for undertaking various hedge transactions and methods for assessing and testing correlation and hedge ineffectiveness.  We and ONEOK Partners specifically identify the forecasted transaction that has been designated as the hedged item with a cash flow hedge.  We and ONEOK Partners 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.  ONEOK Partners also documents its normal purchases and normal sales transactions that are expected to result in physical delivery and that ONEOK Partners elects to exempt from derivative accounting treatment.
	The realized revenues and purchase costs of our and ONEOK Partners 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 Consolidated Statement of Cash Flows category as the cash flows from the related hedged items.
	Income from discontinued operations in our Consolidated Statements of Income includes revenues from financial trading margins, as well as certain physical natural gas transactions with our trading counterparties. Revenues and cost of sales and fuel from such physical transactions are reported on a net basis. See Note B for disclosures of our discontinued operations.
	See Notes D and E for more discussion of our fair value measurements and risk management and hedging activities using derivatives.
	Property, Plant and Equipment - Our properties are stated at cost, including AFUDC. Generally, the cost of regulated property retired or sold, plus removal costs, less salvage, is charged to accumulated depreciation. Gains and losses from sales or transfers of nonregulated properties or an entire operating unit or system of our regulated properties are recognized in income. Maintenance and repairs are charged directly to expense.
	The interest portion of AFUDC represents the cost of borrowed funds used to finance construction activities. We capitalize interest costs during the construction or upgrade of qualifying assets. Capitalized interest is recorded as a reduction to interest expense. The equity portion of AFUDC represents the capitalization of the estimated average cost of equity used during the construction of major projects and is recorded in the cost of our regulated properties and as a credit to the allowance for equity funds used during construction.
	Our properties are depreciated using the straight-line method over their estimated useful lives. Generally, we apply composite depreciation rates to functional groups of property having similar economic circumstances. We periodically conduct depreciation studies to assess the economic lives of our assets. For our regulated assets, these depreciation studies are completed as a part of our rate proceedings or tariff filings, and the changes in economic lives, if applicable, are implemented prospectively when the new rates are billed. For our nonregulated assets, if it is determined that the estimated economic life changes, the changes are made prospectively. Changes in the estimated economic lives of our property, plant and equipment could have a material effect on our financial position or results of operations.
	Property, plant and equipment on our Consolidated Balance Sheets includes construction work in process for capital projects that have not yet been placed in service and therefore are not being depreciated. Assets are transferred out of construction work in process when they are substantially complete and ready for their intended use.
	See Note F for disclosures of our property, plant and equipment.
	Impairment of Goodwill and Long-Lived Assets, Including Intangible Assets - We assess our goodwill and indefinite-lived intangible assets for impairment at least annually as of July 1. Our goodwill impairment analysis performed as of July 1, 2014, did not result in an impairment charge nor did our analysis reflect any reporting units at risk, and subsequent to that date, no event has occurred indicating that the implied fair value of each of our reporting units (including its inherent goodwill) is less than the carrying value of its net assets.
There were no impairment charges resulting from our 2014 and 2013 annual impairment tests. As a result of the decline in natural gas prices and its effect on location and seasonal price differentials, we performed an interim impairment assessment of our former energy services business’s goodwill balance as of March 31, 2012.  As a result of that assessment, goodwill with a carrying amount of $10.3 million was written down to its implied fair value of zero, with a resulting impairment charge of $10.3 million recorded in 2012 earnings, which is included in income from discontinued operations. There were no impairment indicators for ONEOK Partners or our former natural gas distribution business as the cash flows generated from each of these businesses are derived from predominately fee-based, nondiscretionary services.
As part of our impairment test, we first assess qualitative factors (including macroeconomic conditions, industry and market considerations, cost factors and overall financial performance) to determine whether it is more likely than not that the fair value of each of our reporting units is less than its carrying amount. If further testing is necessary, we perform a two-step impairment test for goodwill. In the first step, an initial assessment is made by comparing the fair value of a reporting unit with its book value, including goodwill. If the fair value is less than the book value, an impairment is indicated, and we must perform a second test to measure the amount of the impairment. In the second test, we calculate the implied fair value of the goodwill by deducting the fair value of all tangible and intangible net assets of the reporting unit from the fair value determined in step one of the assessment. If the carrying value of the goodwill exceeds the implied fair value of the goodwill, we will record an impairment charge.
To estimate the fair value of our reporting units, we use two generally accepted valuation approaches, an income approach and a market approach, using assumptions consistent with a market participant’s perspective. Under the income approach, we use anticipated cash flows over a period of years plus a terminal value and discount these amounts to their present value using appropriate discount rates. Under the market approach, we apply EBITDA multiples to forecasted EBITDA. The multiples used are consistent with historical asset transactions. The forecasted cash flows are based on average forecasted cash flows for a reporting unit over a period of years.
As part of our indefinite-lived intangible asset impairment test, we first assess qualitative factors similar to those considered in the goodwill impairment test to determine whether it is more likely than not that the indefinite-lived intangible asset was impaired. If further testing is necessary, we compare the estimated fair value of our indefinite-lived intangible asset with its book value. The fair value of our indefinite-lived intangible asset is estimated using the market approach. Under the market approach, we apply multiples to forecasted cash flows of the assets associated with our indefinite-lived intangible asset. The multiples used are consistent with historical asset transactions. After assessing qualitative factors, we determined that there were no impairments to our indefinite-lived intangible asset in 2014. There were also no impairment charges resulting from our 2013 and 2012 annual impairment tests.
We assess our long-lived assets, including intangible assets with finite useful lives, for impairment whenever events or changes in circumstances indicate that an asset’s carrying amount may not be recoverable. An impairment is indicated if the carrying amount of a long-lived asset exceeds the sum of the undiscounted future cash flows expected to result from the use and eventual disposition of the asset. If an impairment is indicated, we record an impairment loss equal to the difference between the carrying value and the fair value of the long-lived asset. We determined that there were no asset impairments in 2014, 2013 or 2012.
For the investments we account for under the equity method, the impairment test considers whether the fair value of the equity investment as a whole, not the underlying net assets, has declined and whether that decline is other than temporary. Therefore, we periodically reevaluate the amount at which we carry our equity method investments to determine whether current events or circumstances warrant adjustments to our carrying value.
See Notes F, G and P for our long-lived assets, goodwill and intangible assets and investment in unconsolidated affiliates disclosures.
Regulation - ONEOK Partners’ intrastate natural gas transmission pipelines and our former natural gas distribution business are subject to the rate regulation and accounting requirements of the OCC, KCC, RRC and various municipalities in Texas. ONEOK Partners’ interstate natural gas and natural gas liquids pipelines are subject to regulation by the FERC. In Kansas and Texas, natural gas storage may be regulated by the state and the FERC for certain types of services. Oklahoma Natural Gas, Kansas Gas Service, Texas Gas Service, which are all part of our former natural gas distribution business, and portions of the Natural Gas Liquids and Natural Gas Pipelines segments follow the accounting and reporting guidance for regulated operations. During the rate-making process for certain of ONEOK Partners’ assets, regulatory authorities set the framework for what we can charge customers for our services and establish the manner that our costs are accounted for, including allowing us to defer recognition of certain costs and permitting recovery of the amounts through rates over time, as opposed to expensing such costs as incurred. Certain examples of types of regulatory guidance include costs for fuel and losses, acquisition costs, contributions in aid of construction, charges for depreciation and gains or losses on disposition of assets. This allows us to stabilize rates over time rather than passing such costs on to the customer for immediate recovery. Actions by regulatory authorities could have an effect on the amount recovered from rate payers. Any difference in the amount recoverable and the amount deferred is recorded as income or expense at the time of the regulatory action. A write-off of regulatory assets and costs not recovered may be required if all or a portion of the regulated operations have rates that are no longer:
•	established by independent, third-party regulators;
•	designed to recover the specific entity’s costs of providing regulated services; and
•	set at levels that will recover our costs when considering the demand and competition for our services.
In December 2013, the KCC approved a settlement agreement for the separation of our Kansas Gas Service natural gas distribution business to ONE Gas from ONEOK. The terms of the settlement agreement provided that amounts previously recorded as a regulatory asset related to ONEOK’s acquisition of Kansas Gas Service in 1997 would no longer be recovered in rates. As a result, the carrying amount of the regulatory asset was written off, and we recorded a noncash charge to income from discontinued operations of approximately $10.2 million in the fourth quarter 2013.
At December 31, 2014 and 2013, we recorded regulatory assets of approximately $6.1 million and $383.6 million, respectively, which are being recovered or are expected to be recovered as a result of various approved rate proceedings.  Of these amounts, the total regulatory assets related to our former natural gas distribution business were $376.8 million at December 31, 2013, which are included in assets of discontinued operations. The natural gas distribution balances included approximately $341.1 million related to our pension and postretirement benefit plans at December 31, 2013, which are discussed in Note N. Regulatory assets for our continuing operations, which are reflected in other assets in our Consolidated Balance Sheets, are being recovered as a result of approved rate proceedings over varying time periods up to 40 years.
Pension and Postretirement Employee Benefits - We have a defined benefit retirement plan covering certain full-time employees. We sponsor welfare plans that provide postretirement medical and life insurance benefits to certain employees who retire with at least five years of service.  Our actuarial consultant calculates the expense and liability related to these plans and uses statistical and other factors that attempt to anticipate future events. These factors include assumptions about the discount rate, expected return on plan assets, rate of future compensation increases, mortality and employment length. In determining the projected benefit obligations and costs, assumptions can change from period to period and may result in material changes in the costs and liabilities we recognize. See Note N for more discussion of pension and postretirement employee benefits.
Income Taxes - Deferred income taxes are provided for the difference between the financial statement and income tax basis of assets and liabilities and carryforward items based on income tax laws and rates existing at the time the temporary differences are expected to reverse.  Except for the regulated companies, the effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date of the rate change.  For regulated companies, the effect on deferred tax assets and liabilities of a change in tax rates is recorded as regulatory assets and regulatory liabilities in the period that includes the enactment date, if, as a result of an action by a regulator, it is probable that the effect of the change in tax rates will be recovered from or returned to customers through future rates.
We utilize a more-likely-than-not recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position that is taken or expected to be taken in a tax return.  We reflect penalties and interest as part of income tax expense as they become applicable for tax provisions that do not meet the more-likely-than-not recognition threshold and measurement attribute.  During 2014, 2013 and 2012, our tax positions did not require an establishment of a material reserve.
We utilize the “with-and-without” approach for intra-period tax allocation for purposes of allocating total tax expense (or benefit) for the year among the various financial statement components.
We file numerous consolidated and separate income tax returns with federal tax authorities of the United States and Canada along with the tax authorities of several states.  There are no United States federal audits or statute waivers at this time. See Note O for additional discussion of income taxes.
Asset Retirement Obligations - Asset retirement obligations represent legal obligations associated with the retirement of long-lived assets that result from the acquisition, construction, development and/or normal use of the asset. Certain long-lived assets that comprise our former natural gas distribution systems and ONEOK Partners’ natural gas gathering and processing, natural gas liquids and pipeline facilities are subject to agreements or regulations that give rise to asset retirement obligations for removal or other disposition costs associated with retiring the assets in place upon the discontinued use of the assets. We recognize the fair value of a liability for an asset-retirement obligation in the period when it is incurred if a reasonable estimate of the fair value can be made. We are not able to estimate reasonably the fair value of the asset retirement obligations for portions of our former natural gas distribution and ONEOK Partners’ assets, primarily certain pipeline estimates, because the settlement dates are indeterminable given the expected continued use of the assets with proper maintenance. We expect our former natural gas distribution and ONEOK Partners’ pipeline assets, for which we are unable to estimate reasonably the fair value of the asset retirement obligation, will continue in operation as long as supply and demand for natural gas and natural gas liquids exists. Based on the widespread use of natural gas for heating and cooking activities for residential users and electric-power generation for commercial users, as well as use of natural gas liquids by the petrochemical industry, we expect supply and demand to exist for the foreseeable future.
For our assets that we are able to make an estimate, the fair value of the liability is added to the carrying amount of the associated asset, and this additional carrying amount is depreciated over the life of the asset. The liability is accreted at the end of each period through charges to operating expense. If the obligation is settled for an amount other than the carrying amount of the liability, we will recognize a gain or loss on settlement. The depreciation and accretion expense are immaterial to our consolidated financial statements.
In accordance with long-standing regulatory treatment, ONEOK Partners and our former natural gas distribution business collect, through rates, the estimated costs of removal on certain regulated properties through depreciation expense, with a corresponding credit to accumulated depreciation and amortization. These removal costs collected through rates include legal and nonlegal removal obligations; however, the amounts collected in excess of the asset-removal costs incurred are accounted for as a regulatory liability for financial reporting purposes. Historically, with the exception of the regulatory authority in Kansas, the regulatory authorities that have jurisdiction over our regulated operations have not required us to quantify this amount; rather, these costs are addressed prospectively in depreciation rates and are set in each general rate order. We have made an estimate of our regulatory liability using current rates since the last general rate order in each of our jurisdictions; however, for financial reporting purposes, significant uncertainty exists regarding the ultimate disposition of this regulatory liability, pending, among other issues, clarification of regulatory intent. We continue to monitor regulatory requirements, and the liability may be adjusted as more information is obtained.
Contingencies - Our accounting for contingencies covers a variety of business activities, including contingencies for legal and environmental exposures. We accrue these contingencies when our assessments indicate that it is probable that a liability has been incurred or an asset will not be recovered and an amount can be estimated reasonably. We expense legal fees as incurred and base our legal liability estimates on currently available facts and our estimates of the ultimate outcome or resolution. Accruals for estimated losses from environmental remediation obligations generally are recognized no later than completion of a remediation feasibility study. Recoveries of environmental remediation costs from other parties are recorded as assets when their receipt is deemed probable. Our expenditures for environmental evaluation, mitigation, remediation and compliance to date have not been significant in relation to our financial position or results of operations, and our expenditures related to environmental matters had no material effect on earnings or cash flows during 2014, 2013 and 2012. Actual results may differ from our estimates resulting in an impact, positive or negative, on earnings. See Note R for additional discussion of contingencies.
Share-Based Payments - We expense the fair value of share-based payments net of estimated forfeitures.  We estimate forfeiture rates based on historical forfeitures under our share-based payment plans.
Earnings per Common Share - Basic EPS is calculated based on the daily weighted-average number of shares of common stock outstanding during the period. Diluted EPS is calculated based on the daily weighted-average number of shares of common stock outstanding during the period plus potentially dilutive components. The dilutive components are calculated based on the dilutive effect for each quarter. For fiscal-year periods, the dilutive components for each quarter are averaged to arrive at the fiscal year-to-date dilutive component.
Recently Issued Accounting Standards Update - In February 2015. the FASB issued ASU 2015-02, “Consolidation (Topic 810): Amendments to the Consolidation Analysis,” which eliminates the presumption that a general partner should consolidate a limited partnership. It also modifies the evaluation of whether limited partnerships are variable interest entities or voting interest entities and adds requirements that limited partnerships must meet to qualify as voting interest entities. This guidance is effective for public companies for fiscal years beginning after December 15, 2015. We will adopt this guidance in the first quarter 2016, and we are evaluating the impact on us.
In November 2014, the FASB issued ASU 2014-17, “Business Combination (Topic 805): Pushdown Accounting,” which provides an acquired entity with an option to apply pushdown accounting in its separate financial statements when a change-in-control event occurs. An acquired entity may elect the option to apply pushdown accounting in the reporting period in which the change-in-control event occurs. The standard applies to all entities and was effective on November 18, 2014. We adopted this guidance beginning in the fourth quarter 2014, and we do not expect it to materially impact us.
In August 2014, the FASB issued ASU 2014-15, “Going Concern,” which provides guidance on determining when and how to disclose going-concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if conditions or events raise substantial doubt about the entity’s ability to continue as a going concern. The standard applies to all entities and is effective for annual periods ending after December 15, 2016, and interim periods thereafter, with early adoption permitted. We will adopt this guidance beginning in the first quarter 2016, and we do not expect it to materially impact us.
In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers,” which outlines the principles an entity must apply to measure and recognize revenue for entities that enter into contracts to provide goods or services to their customers. The core principle is that an entity should recognize revenue at an amount that reflects the consideration to which the entity expects to be entitled in exchange for transferring goods or services to a customer. The amendment also requires more extensive disaggregated revenue disclosures in interim and annual financial statements. This update will be effective for interim and annual periods that begin on or after December 15, 2016, with either retrospective application for all periods presented or retrospective application with a cumulative effect adjustment. We will adopt this guidance beginning in the first quarter 2017, and we are evaluating the impact on us.
In April 2014, the FASB issued ASU 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity,” which alters the definition of a discontinued operation to include only asset disposals that represent a strategic shift with a major effect on an entity's operations and financial results.  The amendment also requires more extensive disclosures about a discontinued operation’s assets, liabilities, income, expenses and cash flows. This guidance will be effective for interim and annual periods for all assets that are disposed of or classified as being held for sale in fiscal years that begin on or after December 15, 2014. We will adopt this guidance beginning in the first quarter 2015, and it could impact us in the future if we dispose of any individually significant components.

DISCONTINUED_OPERATIONS

DISCONTINUED OPERATIONS	12 Months Ended
	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
DISCONTINUED OPERATIONS	B.DISCONTINUED OPERATIONS
	Separation of ONE Gas - On January 31, 2014, we completed the separation of ONE Gas. ONE Gas consists of our former natural gas distribution business that includes Kansas Gas Service, Oklahoma Natural Gas and Texas Gas Service. ONEOK shareholders of record at the close of business on January 21, 2014, retained their shares of ONEOK stock and received one share of ONE Gas stock for every four shares of ONEOK stock owned in a transaction that was tax-free to ONEOK and its shareholders. ONE Gas shares were distributed following the close of business on January 31, 2014. We retained no ownership interest in ONE Gas. On the date of the separation, ONE Gas consisted of approximately $4.3 billion of assets, $2.6 billion of liabilities and $1.7 billion of equity. Excluding cash of ONE Gas at separation, the separation was accounted for as a noncash activity.
	On February 1, 2012, we sold ONEOK Energy Marketing Company, our former natural gas distribution business’ retail natural gas marketing business, to Constellation Energy Group, Inc. for $22.5 million plus working capital.  We received net proceeds of approximately $32.9 million and recognized a gain on the sale of approximately $13.5 million, net of taxes of $8.3 million. The proceeds from the sale were used to reduce short-term borrowings.
	Wind Down of Energy Services Business - On March 31, 2014, we completed the wind down of our energy services business. We executed agreements in 2013 to release a significant portion of our nonaffiliated natural gas transportation and storage contracts to third parties between July 1 and December 31, 2013, at current market rates that resulted in noncash charges of $138.6 million. We executed an agreement in the first quarter 2014 to release a nonaffiliated, third-party natural gas storage contract to a third party, resulting in a noncash charge of $1.7 million. All of the remaining natural gas transportation and storage contracts not previously released or assigned expired on their own terms on or before March 31, 2014. Our energy services business continued to serve its contracted premium-services customers until these remaining contracts expired on or before March 31, 2014.
	The following table summarizes the change in our liability related to released capacity contracts for the period indicated:
		Years Ended December 31,
		2014				2013
		(Millions of dollars)
	Beginning balance	$	122			$	—
	Noncash charges	1.7				138.6
	Settlements	(51.8		)		(17.7		)
	Accretion	1.9				1.1
	Ending balance	$	73.8			$	122
	We recorded these charges in income from discontinued operations, net of tax in our Consolidated Statements of Income. The total charge attributable to severance benefits was not material. We expect future cash payments associated with released transportation and storage capacity from the wind down of our former energy services business to total approximately $45 million on an after-tax basis, which consists of approximately $23 million paid in 2015, $11 million in 2016, $6 million in 2017, and $5 million during the period from 2018 through 2023.
	Results of Operations of Discontinued Operations - The results of operations for our former natural gas distribution business, including ONEOK Energy Marketing Company, and energy services business have been reported as discontinued operations for all periods presented. The tables below provide selected financial information reported in discontinued operations in the Consolidated Statements of Income for the periods presented:
		Year Ended
		31-Dec-14
		Natural Gas				Energy			Total
		Distribution				Services
		(Thousands of dollars)
	Revenues	$	287,249			$	353,404		$	640,653
	Cost of sales and fuel	190,893				364,648			555,541
	Net margin	96,356				(11,244		)	85,112
	Operating costs	60,847			(a)	5,051			65,898
	Depreciation and amortization	11,035				319			11,354
	Operating income (loss)	24,474				(16,614		)	7,860
	Other income (expense), net	(888		)		(7		)	(895		)
	Interest expense, net	(4,592		)		(413		)	(5,005		)
	Income tax benefit (expense)	(16,415		)		8,848			(7,567		)
	Income (loss) from discontinued operations, net	$	2,579			$	(8,186	)	$	(5,607	)
	(a) - Includes approximately $23.0 million for the year ended December 31, 2014, of costs related to the ONE Gas separation.
		Year Ended
		31-Dec-13
		Natural Gas				Energy			Total
		Distribution				Services
		(Thousands of dollars)
	Revenues	$	1,689,945			$	1,381,636		$	3,071,581
	Cost of sales and fuel	876,944				1,554,621			2,431,565
	Net margin	813,001				(172,985		)	640,016
	Operating costs	436,281			(a)	12,586			448,867
	Depreciation and amortization	144,758				276			145,034
	Operating income (loss)	231,962				(185,847		)	46,115
	Other income (expense), net	2,484				135			2,619
	Interest expense, net	(61,366		)		(2,195		)	(63,561		)
	Income tax benefit (expense)	(64,307		)		67,005			2,698
	Income (loss) from discontinued operations, net	$	108,773			$	(120,902	)	$	(12,129	)
	(a) - Includes approximately $9.4 million for the year ended December 31, 2013, of costs related to the ONE Gas separation.
		Year Ended
		31-Dec-12
		Natural Gas				Energy			Total
		Distribution				Services
		(Thousands of dollars)
	Revenues	$	1,404,248			$	1,421,171		$	2,825,419
	Cost of sales and fuel	646,220				1,470,514			2,116,734
	Net margin	758,028				(49,343		)	708,685
	Operating costs	400,247				17,414			417,661
	Depreciation and amortization	130,158				360			130,518
	Goodwill impairment	—				10,255			10,255
	Operating income (loss)	227,623				(77,372		)	150,251
	Other income (expense), net	1,439				147			1,586
	Interest expense, net	(60,794		)		(3,874		)	(64,668		)
	Income tax benefit (expense)	(63,647		)		28,743			(34,904		)
	Income (loss) from discontinued operations, net	$	104,621			$	(52,356	)	$	52,265
	Prior to the ONE Gas separation, natural gas sales and transportation and storage services provided to our former natural gas distribution business by ONEOK Partners were $7.5 million, $64.5 million and $49.4 million for the years ended December 31, 2014, 2013 and 2012, respectively. Prior to February 1, 2014, these revenues and related costs were eliminated in consolidation. Beginning February 1, 2014, these revenues represent third-party transactions with ONE Gas and are not eliminated in consolidation for all periods presented, as such sales and services have continued subsequent to the separation and are expected to continue in future periods.
Prior to the completion of the energy services wind down, natural gas sales and transportation and storage services provided to our energy services business by ONEOK Partners were $46.0 million, $276.3 million and $299.9 million for the years ended December 31, 2014, 2013 and 2012, respectively. While these transactions were eliminated in consolidation in previous periods, they are reflected now as affiliate transactions and not eliminated in consolidation for all periods presented, as these transactions have continued with third parties.
Statement of Financial Position of Discontinued Operations - The following tables present the carrying value of assets and liabilities of our former natural gas distribution and energy services businesses included in assets and liabilities of discontinued operations in the Consolidated Balance Sheets for the periods presented:
	31-Dec-14
	Energy Services
	(Thousands of dollars)
Assets
Other current assets	$	16,717
Other assets	20,020
Total assets	$	36,737
Liabilities
Other current liabilities	$	44,901
Other deferred credits	36,424
Total liabilities	$	81,325
	31-Dec-13
	Natural Gas				Energy			Total
	Distribution				Services
	(Thousands of dollars)
Assets
Cash and cash equivalents	$	3,535			$	213		$	3,748
Accounts receivable, net	368,214				87,315			455,529
Natural gas and natural gas liquids in storage	166,128				62,663			228,791
Other current assets	30,328				29,476			59,804
Net property, plant and equipment	3,065,272				279			3,065,551
Goodwill	157,953				—			157,953
Other assets	402,161				385			402,546
Total assets	$	4,193,591			$	180,331		$	4,373,922
Liabilities
Current maturities of long-term debt	$	6			$	—		$	6
Accounts payable	168,785				77,287			246,072
Other current liabilities	168,964				40,646			209,610
Long-term debt, excluding current maturities	1,318				—			1,318
Deferred income taxes	826,921				(35,221		)	791,700
Other deferred credits	184,214				70,998			255,212
Total liabilities	$	1,350,208			$	153,710		$	1,503,918
ONEOK provided cash management and financial services for our former energy services and natural gas distribution businesses, which included short-term borrowings and long-term notes payable. These intercompany borrowings were eliminated in consolidation and as such are not included in the liabilities of discontinued operations in the tables above. For our former energy services business, short-term borrowings due to ONEOK at December 31, 2013 was $25.1 million, and notes payable to ONEOK at December 31, 2013 was $21.4 million. For our former natural gas distribution business, short-term borrowings due to ONEOK at December 31, 2013 was $130.0 million and notes payable to ONEOK at December 31, 2013 was $1.0 billion.
Restructuring and Related Costs [Table Text Block]	The following table summarizes the change in our liability related to released capacity contracts for the period indicated:
		Years Ended December 31,
		2014				2013
		(Millions of dollars)
	Beginning balance	$	122			$	—
	Noncash charges	1.7				138.6
	Settlements	(51.8		)		(17.7		)
	Accretion	1.9				1.1
	Ending balance	$	73.8			$	122

ACQUISITIONS_ACQUISITIONS

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

FAIR_VALUE_MEASUREMENTS

FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	D.FAIR VALUE MEASUREMENTS
	Recurring Fair Value Measurements - The following tables set forth our recurring fair value measurements for the periods indicated:
		December 31, 2014
		Level 1			Level 2			Level 3			Total - Gross			Netting (a)			Total - Net (b)
		(Thousands of dollars)
	Assets
	Derivatives
	Commodity contracts
	Financial contracts	$	42,880		$	—		$	354		$	43,234		$	(25,979	)	$	17,255
	Physical contracts	—			—			9,922			9,922			—			9,922
	Interest-rate contracts	—			2,288			—			2,288			—			2,288
	Total derivative assets	42,880			2,288			10,276			55,444			(25,979		)	29,465
	Available-for-sale investment securities	1,773			—			—			1,773			—			1,773
	Total assets	$	44,653		$	2,288		$	10,276		$	57,217		$	(25,979	)	$	31,238
	Liabilities
	Derivatives
	Commodity contracts
	Financial contracts	$	(169	)	$	—		$	(968	)	$	(1,137	)	$	1,137		$	—
	Physical contracts	—			—			(23		)	(23		)	—			(23		)
	Interest-rate contracts	—			(44,843		)	—			(44,843		)	—			(44,843		)
	Total derivative liabilities	$	(169	)	$	(44,843	)	$	(991	)	$	(46,003	)	$	1,137		$	(44,866	)
	(a) - 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 ONEOK Partners. At December 31, 2014, ONEOK Partners had $24.8 million of cash held from various counterparties and posted no cash collateral.
	(b) - Included in other current assets, other assets or other current liabilities in our Consolidated Balance Sheets.
		December 31, 2013
		Level 1			Level 2			Level 3			Total - Gross			Netting (a)			Total - Net (b)
		(Thousands of dollars)
	Assets
	Derivatives
	Commodity contracts
	Financial contracts	$	—		$	3,657		$	2,812		$	6,469		$	(1,746	)	$	4,723
	Physical contracts	—			—			2,023			2,023			(946		)	1,077
	Interest-rate contracts	—			54,503			—			54,503			—			54,503
	Total derivative assets	—			58,160			4,835			62,995			(2,692		)	60,303
	Available-for-sale investment securities	1,569			—			—			1,569			—			1,569
	Total assets	$	1,569		$	58,160		$	4,835		$	64,564		$	(2,692	)	$	61,872
	Liabilities
	Derivatives
	Commodity contracts
	Financial contracts	$	—		$	(2,953	)	$	(2,154	)	$	(5,107	)	$	1,746		$	(3,361	)
	Physical contracts	—			—			(3,463		)	(3,463		)	946			(2,517		)
	Total derivative liabilities	$	—		$	(2,953	)	$	(5,617	)	$	(8,570	)	$	2,692		$	(5,878	)
	(a) - 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 ONEOK Partners. At December 31, 2013, ONEOK Partners had no cash collateral held or posted.
	(b) - Included in other current assets, other assets or other current liabilities in our Consolidated Balance Sheets.
	The following tables set forth the reconciliation of our Level 3 fair value measurements for our continuing operations for the periods indicated:
		Years Ended December 31,
	Derivative Assets (Liabilities)	2014			2013
		(Thousands of dollars)
	Net assets (liabilities) at beginning of period	$	(782	)	$	(2,423	)
	Total realized/unrealized gains (losses):
	Included in earnings (a)	(927		)	959
	Included in other comprehensive income (loss)	7,260			682
	Purchases, issuances and settlements	3,734			—
	Net assets (liabilities) at end of period	$	9,285		$	(782	)
	Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets and liabilities still held as of the end of the period (a)	$	31		$	959
	(a) - Reported in commodity sales revenues in our Consolidated Statements of Income.
	During the years ended December 31, 2014 and 2013, there were no transfers between levels.
	Other Financial Instruments - The approximate fair value of cash and cash equivalents, accounts receivable, accounts payable and notes payable is equal to book value, due to the short-term nature of these items. Our cash and cash equivalents are comprised of bank and money market accounts and are classified as Level 1. Our notes payable are classified as Level 2 since the estimated fair value of the notes payable can be determined using information available in the commercial paper market.
	The estimated fair value of our consolidated long-term debt, including current maturities, was $7.5 billion and $8.2 billion at December 31, 2014 and 2013, respectively.  The book value of long-term debt, including current maturities, was $7.2 billion and $7.8 billion at December 31, 2014 and 2013, respectively.  The estimated fair value of the aggregate of ONEOK’s and ONEOK Partners’ long-term debt outstanding was determined using quoted market prices for similar issues with similar terms and maturities.  The estimated fair value of our consolidated long-term debt is classified as Level 2.
	During 2014, ONEOK Partners recorded a noncash impairment to its equity investment in Bighorn Gas Gathering. The valuation of this investment required use of significant unobservable inputs. ONEOK Partners used an income approach to estimate the fair value of its investment. ONEOK Partners’ discounted cash flow analysis included the following inputs that are not readily available: a discount rate reflective of its cost of capital and estimated contract rates, volumes, operating and maintenance costs and capital expenditures. The estimated fair value of this investment is classified as Level 3. See Note P for additional information about ONEOK Partners’ investment in Bighorn Gas Gathering and the impairment charge.

RISK_MANAGEMENT_AND_HEDGING_AC

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES
	E.	RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES
	Risk-Management Activities - ONEOK Partners is 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. ONEOK Partners uses physical-forward sales and financial derivatives to secure a certain price for a portion of its natural gas, condensate and NGL products. ONEOK Partners follows established policies and procedures to assess risk and approve, monitor and report its risk-management activities. ONEOK Partners has not used these instruments for trading purposes. We and ONEOK Partners are also subject to the risk of interest-rate fluctuation in the normal course of business.
	Commodity price risk - ONEOK Partners is exposed to the risk of loss in cash flows and future earnings arising from adverse changes in the price of natural gas, NGLs and condensate. ONEOK Partners uses the following commodity derivative instruments to mitigate the near-term commodity price risk associated with a portion of the forecasted sales of these commodities:
	•	Futures contracts - Standardized contracts to purchase or sell natural gas and crude oil for future delivery or settlement under the provisions of exchange regulations;
	•	Forward contracts - Nonstandardized commitments between two parties to purchase or sell natural gas, crude oil or NGLs for future physical delivery. These contracts are typically nontransferable and can only be canceled with the consent of both parties; and
	•	Swaps - Exchange of one or more payments based on the value of one or more commodities. These instruments transfer the financial risk associated with a future change in value between the counterparties of the transaction, without also conveying ownership interest in the asset or liability.
	We may also use other instruments including options or collars to mitigate commodity price risk. Options are contractual agreements that give the holder the right, but not the obligation, to buy or sell a fixed quantity of a commodity, at a fixed price, within a specified period of time. Options may either be standardized and exchange traded or customized and nonexchange traded. A collar is a combination of a purchased put option and a sold call option, which places a floor and a ceiling price for commodity sales being hedged.
	The Natural Gas Gathering and Processing segment is exposed to commodity price risk as a result of receiving commodities in exchange for services associated with its POP contracts. ONEOK Partners is also exposed to basis risk between the various production and market locations where it receives and sells commodities. As part of ONEOK Partners’ hedging strategy, it uses the previously described commodity derivative financial instruments and physical-forward contracts to reduce the impact of price fluctuations related to natural gas, NGLs and condensate.
	The Natural Gas Liquids segment is 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, ONEOK Partners is 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. ONEOK Partners utilizes physical-forward contracts to reduce the impact of price fluctuations related to NGLs. At December 31, 2014 and 2013, there were no financial derivative instruments with respect to ONEOK Partners’ natural gas liquids operations.
	The Natural Gas Pipelines segment is exposed to commodity price risk because its intrastate and interstate natural gas pipelines retain natural gas from its customers for operations or as part of its fee for services provided. When the amount of natural gas consumed in operations by these pipelines differs from the amount provided by its customers, ONEOK Partners’ pipelines must buy or sell natural gas, or store or use natural gas from inventory, which can expose it to commodity price risk depending on the regulatory treatment for this activity. To the extent that commodity price risk in the Natural Gas Pipelines segment is not mitigated by fuel cost-recovery mechanisms, it uses physical-forward sales or purchases to reduce the impact of price fluctuations related to natural gas. At December 31, 2014 and 2013, there were no financial derivative instruments with respect to ONEOK Partners’ natural gas pipeline operations.
	Interest-rate risk - We and ONEOK Partners manage interest-rate risk through the use of fixed-rate debt, floating-rate debt and interest-rate swaps. Interest-rate swaps are agreements to exchange interest payments at some future point based on specified notional amounts. At December 31, 2014 and 2013, ONEOK Partners had forward-starting interest-rate swaps with notional amounts totaling $900 million and $400 million, respectively, that have been designated as cash flow hedges of the variability of interest payments on a portion of forecasted debt issuances that may result from changes in the benchmark interest rate before the debt is issued. At December 31, 2014, notional amounts totaling $400 million have settlement dates greater than 12 months.
	Fair Values of Derivative Instruments - The following table sets forth the fair values of our derivative instruments for our continuing operations for the periods indicated:
		December 31, 2014								December 31, 2013
		Assets (a)				(Liabilities) (a)				Assets (a)				(Liabilities) (a)
		(Thousands of dollars)
	Derivatives designated as hedging instruments
	Commodity contracts
	Financial contracts	$	43,234			$	(1,137	)		$	6,469			$	(5,107	)
	Physical contracts	9,922				—				1,064				(3,463		)
	Interest-rate contracts	2,288				(44,843		)		54,503				—
	Total derivatives designated as hedging instruments	55,444				(45,980		)		62,036				(8,570		)
	Derivatives not designated as hedging instruments
	Commodity contracts
	Physical contracts	—				(23		)		959				—
	Total derivatives not designated as hedging instruments	—				(23		)		959				—
	Total derivatives	$	55,444			$	(46,003	)		$	62,995			$	(8,570	)
	(a) - Included on a net basis in other current assets, other assets or other current liabilities on our Consolidated Balance Sheets.
	Notional Quantities for Derivative Instruments - The following table sets forth the notional quantities for derivative instruments held for our continuing operations for the periods indicated:
				December 31, 2014								December 31, 2013
		Contract		Purchased/				Sold/				Purchased/				Sold/
		Type		Payor				Receiver				Payor				Receiver
	Derivatives designated as hedging instruments:
	Cash flow hedges
	Fixed price
	-Natural gas (Bcf)	Futures and swaps		—				(41.2		)		—				(48.1		)
	-Crude oil and NGLs (MMBbl)	Futures, forwards and swaps		—				(0.5		)		—				(4.0		)
	Basis
	-Natural gas (Bcf)	Futures and swaps		—				(41.2		)		—				(48.1		)
	Interest-rate contracts (Millions of dollars)	Forward-starting		$	900			$	—			$	400			$	—
		swaps
	These notional amounts are used to summarize the volume of financial instruments; however, they do not reflect the extent to which the positions offset one another and consequently do not reflect our actual exposure to market or credit risk.
	Cash Flow Hedges - ONEOK Partners uses derivative instruments to hedge the cash flows associated with anticipated purchases and sales of natural gas, NGLs and condensate and cost of fuel used in the transportation of natural gas.  Accumulated other comprehensive income (loss) at December 31, 2014, includes gains of approximately $12.8 million, net of tax, related to these hedges that will be recognized within the next 12 months as the forecasted transactions affect earnings and if commodity prices remain at current levels.  The amount deferred in accumulated other comprehensive income (loss) attributable to our settled interest-rate swaps is a loss of $38.4 million, net of tax, which will be recognized over the life of the long-term, fixed-rate debt. We expect that losses of $4.7 million, net of tax, 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 ONEOK Partners’ forward-starting interest-rate swaps, which will be amortized to interest expense over the life of long-term, fixed-rate debt upon issuance of ONEOK Partners debt.
	For the year ended December 31, 2013, income from discontinued operations in our Consolidated Statement of Income related to our former energy services business included $10.1 million reflecting an adjustment to natural gas inventory at the lower of cost or market value. We reclassified $8.0 million of deferred gains, before income taxes, on associated cash flow hedges from accumulated other comprehensive income (loss) into earnings.
	For the year ended December 31, 2012, income from discontinued operations in our Consolidated Statement of Income included losses of $29.9 million related to certain financial contracts that were used to hedge forecasted purchases of natural gas.  As a result of the continued decline in natural gas prices, the combination of the cost basis of the forecasted purchases of inventory and the financial contracts exceeded the amount expected to be recovered through sales of that inventory after considering related sales hedges, which required reclassification of the loss from accumulated other comprehensive loss to current period earnings.
	The following table sets forth the unrealized effect of cash flow hedges recognized in other comprehensive income (loss) for the periods indicated:
	Derivatives in Cash Flow		Years Ended December 31,
	Hedging Relationships		2014				2013				2012
			(Thousands of dollars)
	Continuing Operations
	Commodity contracts		$	32,354			$	(14,475	)		$	46,804
	Interest-rate contracts		(96,993		)		46,616				(29,471		)
	Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion) for continuing operations		(64,639		)		32,141				17,333
	Discontinued Operations
	Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion) for discontinued operations - commodity contracts		(3,697		)		(958		)		16,094
	Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion)		$	(68,336	)		$	31,183			$	33,427
	The following tables set forth the effect of cash flow hedges on our Consolidated Statements of Income for the periods indicated:
			Location of Gain (Loss) Reclassified from
	Derivatives in Cash Flow		Accumulated Other Comprehensive Income		Years Ended December 31,
	Hedging Relationships		(Loss) into Net Income (Effective Portion)		2014				2013				2012
					(Thousands of dollars)
	Continuing Operations
	Commodity contracts		Commodity sales revenues		$	(21,052	)		$	1,689			$	61,526
	Interest-rate contracts		Interest expense		(21,966		)		(14,560		)		(7,155		)
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income from continuing operations on derivatives (effective portion)				(43,018		)		(12,871		)		54,371
Discontinued Operations
Commodity contracts		Income (loss) from discontinued operations -		(12,803		)		17,360				79,336
		Commodity sales revenues
Commodity contracts		Income (loss) from discontinued operations -		—				(14,320		)		(73,881		)
		Cost of sales and fuel
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income from discontinued operations on derivatives (effective portion)				(12,803		)		3,040				5,455
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion)				$	(55,821	)		$	(9,831	)		$	59,826
Ineffectiveness related to our former energy services business’ and ONEOK Partners’ cash flow hedges was not material for the years ended December 31, 2014, 2013 and 2012.  In the event that it becomes probable that a forecasted transaction will not occur, we will discontinue cash flow hedge treatment, which will affect earnings.  For the year ended December 31, 2014, we reclassified losses of $4.6 million, net of taxes of $3.1 million, to interest expense from accumulated other comprehensive income (loss) due to the discontinuance of cash flow hedge treatment from the de-designation of interest-rate swaps related to the early retirement of long-term debt. See Note I for additional information. For the years ended December 31, 2013 and 2012, there were no gains or losses due to the discontinuance of cash flow hedge treatment in our continuing operations as a result of the underlying transactions being no longer probable.
Fair Value Hedges - In prior years, we terminated various interest-rate swap agreements that had been designated as fair value hedges. The net savings from the termination of these swaps is being recognized in interest expense over the terms of the debt instruments originally hedged.  Interest expense savings from the amortization of terminated swaps were $1.7 million for each of the years ended December 31, 2014, 2013 and 2012.
Credit Risk - In the first quarter 2014, outstanding commodity derivative positions with third parties entered into by our energy services business on ONEOK Partners’ behalf were transferred to ONEOK Partners. Beginning in the second quarter 2014, ONEOK Partners enters into all commodity derivative financial contracts directly with unaffiliated third parties.
We and ONEOK Partners monitor the creditworthiness of counterparties and compliance with policies and limits established by our Risk Oversight and Strategy Committee. We and ONEOK Partners maintain credit policies on counterparties that we and ONEOK Partners believe minimize overall credit risk.  These policies include an evaluation of potential counterparties’ financial condition (including credit ratings, bond yields and credit default swap rates), collateral requirements under certain circumstances and the use of standardized master-netting agreements that allow us to net the positive and negative exposures associated with a single counterparty.  ONEOK Partners has counterparties whose credit is not rated, and for those customers it uses internally developed credit ratings.
Some of ONEOK Partners’ financial derivative instruments contain provisions that require it to maintain an investment-grade credit rating from S&P and/or Moody’s.  If ONEOK Partners’ credit ratings on senior unsecured long-term debt were to decline below investment grade, the counterparties to the derivative instruments could request collateralization on derivative instruments in net liability positions. There were no financial derivative instruments with contingent features related to credit risk that were in a net liability position as of December 31, 2014.
The counterparties to ONEOK Partners’ derivative contracts consist primarily of major energy companies, financial institutions and commercial and industrial end users.  This concentration of counterparties may affect ONEOK Partners’ overall exposure to credit risk, either positively or negatively, in that the counterparties may be affected similarly by changes in economic, regulatory or other conditions.  Based on ONEOK Partners’ policies, exposures, credit and other reserves, it does not anticipate a material adverse effect on its financial position or results of operations as a result of counterparty nonperformance.
At December 31, 2014, the net credit exposure from our derivative assets is primarily with investment-grade companies in the financial services sector.

PROPERTY_PLANT_AND_EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT
	F.	PROPERTY, PLANT AND EQUIPMENT
	The following table sets forth our property, plant and equipment for our continuing operations by property type, for the periods indicated:
			Estimated Useful	December 31,			December 31,
			Lives (Years)	2014			2013
				(Thousands of dollars)
	Nonregulated
	Gathering pipelines and related equipment		5 to 40	$	2,449,343		$	2,173,271
	Processing and fractionation and related equipment		3 to 40	2,880,572			2,295,983
	Storage and related equipment		5 to 54	478,276			362,704
	Transmission pipelines and related equipment		5 to 54	518,585			302,718
	General plant and other		2 to 60	364,976			314,919
	Construction work in process		—	1,236,138			1,085,185
	Regulated
	Storage and related equipment		5 to 54	115,799			135,922
	Natural gas transmission pipelines and related equipment		5 to 77	1,478,035			1,420,517
	Natural gas liquids transmission pipelines and related equipment		5 to 80	3,822,799			2,049,461
	General plant and other		2 to 53	63,424			53,315
	Construction work in process		—	194,700			776,261
	Property, plant and equipment			13,602,647			10,970,256
	Accumulated depreciation and amortization - nonregulated			(1,221,387		)	(1,090,268		)
	Accumulated depreciation and amortization - regulated			(718,823		)	(648,034		)
	Net property, plant and equipment			$	11,662,437		$	9,231,954
	The average depreciation rates for our regulated property are set forth, by segment, in the following table for the periods indicated:
			Years Ended December 31,
			2014	2013		2012
	Natural Gas Liquids		2.00%	2.00%		1.90%
	Natural Gas Pipelines		2.10%	2.20%		2.20%
	We and ONEOK Partners incurred liabilities for construction work in process that had not been paid at December 31, 2014, 2013 and 2012, of $187.2 million, $237.2 million and $220.2 million, respectively. Such amounts are not included in capital expenditures (less allowance for equity funds used during construction) on the Consolidated Statements of Cash Flows.

GOODWILL_AND_INTANGIBLE_ASSETS

GOODWILL AND INTANGIBLE ASSETS	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS
	G.	GOODWILL AND INTANGIBLE ASSETS
	Goodwill - The following table sets forth our goodwill by segment for the periods indicated:
		December 31,				December 31,
		2014				2013
		(Thousands of dollars)
	Natural Gas Gathering and Processing	$	122,291			$	122,291
	Natural Gas Liquids	268,544				268,544
	Natural Gas Pipelines	134,700				134,700
	Total goodwill	$	525,535			$	525,535
	In September 2013 ONEOK Partners completed the Sage Creek acquisition, which included goodwill of $20 million and $72 million for the Natural Gas Gathering and Processing segment and Natural Gas Liquids segment, respectively. For additional information related to the acquisition, see Note C.
	Intangible Assets - The following table sets forth the gross carrying amount and accumulated amortization of intangible assets for our continuing operations for the periods indicated:
			December 31,				December 31,
			2014				2013
			(Thousands of dollars)
	Gross intangible assets		$	567,215			$	565,215
	Accumulated amortization		(78,010		)		(66,188		)
	Net intangible assets		$	489,205			$	499,027
	At December 31, 2014 and 2013, ONEOK Partners has $333.6 million and $343.5 million, respectively, of intangible assets related primarily to contracts acquired through acquisitions in the Natural Gas Gathering and Processing and Natural Gas Liquids segments, which are being amortized over a period of 20 to 40 years.  The remaining intangible asset balance has an indefinite life.  Amortization expense for intangible assets for 2014, 2013 and 2012 was $11.8 million, $8.7 million and $7.7 million, respectively, and the aggregate amortization expense for each of the next five years is estimated to be approximately $11.8 million.

CREDIT_FACILITIES_AND_SHORTTER

CREDIT FACILITIES AND SHORT-TERM NOTES PAYABLE CREDIT FACILITIES AND SHORT-TERM NOTES PAYABLE (Notes)	12 Months Ended
	Dec. 31, 2014
CREDIT FACILITIES AND SHORT-TERM NOTES PAYABLE [Abstract]
Short-term Debt [Text Block]
	H.	CREDIT FACILITIES AND SHORT-TERM NOTES PAYABLE
	ONEOK Credit Agreement - The ONEOK Credit Agreement was amended, effective upon the separation of our natural gas distribution business on January 31, 2014, and will expire in January 2019. This amendment reduced the size of our revolving credit facility to $300 million from $1.2 billion and contains certain financial, operational and legal covenants.  Among other things, these covenants include maintaining a ratio of indebtedness to Consolidated EBITDA (EBITDA, as defined in our ONEOK Credit Agreement) of no more than 4.0 to 1. Upon breach of certain covenants by us in our ONEOK Credit Agreement, amounts outstanding under our ONEOK Credit Agreement, if any, may become due and payable immediately. At December 31, 2014, ONEOK’s ratio of indebtedness to Consolidated EBITDA was 2.3 to 1, and ONEOK was in compliance with all covenants under the ONEOK Credit Agreement. As a result of a reduction in the borrowing capacity of the ONEOK Credit Agreement, we wrote off approximately $2.9 million in interest expense of previously deferred credit agreement issuance costs in the first quarter 2014.
	This ONEOK Credit Agreement includes a $50 million sublimit for the issuance of standby letters of credit and a $50 million sublimit for swingline loans.  Under the terms of the ONEOK Credit Agreement, ONEOK may request an increase in the size of the facility to an aggregate of $500 million from $300 million by either commitments from new lenders or increased commitments from existing lenders.  The ONEOK Credit Agreement contains provisions for an applicable margin rate and an annual facility fee, both of which adjust with changes in our credit rating. Based on our current credit rating, borrowings, if any, will accrue interest at LIBOR plus 125 basis points, and the annual facility fee is 25 basis points.
	At December 31, 2014, ONEOK had $1.9 million letters of credit issued. In February 2014, we repaid all commercial paper outstanding, which totaled approximately $600.5 million, and terminated the program.
	ONEOK had no short-term debt outstanding at December 31, 2014.
	ONEOK Partners Credit Agreement - The ONEOK Partners Credit Agreement is available for general partnership purposes, including repayment of ONEOK Partners’ commercial paper notes, if necessary. Amounts outstanding under ONEOK Partners’ commercial paper program reduce the borrowing capacity under the ONEOK Partners Credit Agreement. At December 31, 2014, ONEOK Partners had $1.1 billion of commercial paper outstanding, $14.0 million letters of credit issued and no borrowings under the ONEOK Partners Credit Agreement.
	The ONEOK Partners Credit Agreement, which was amended and restated effective on January 31, 2014, and expires in January 2019, is a $1.7 billion revolving credit facility and includes a $100 million sublimit for the issuance of standby letters of credit, a $150 million swingline sublimit and an option to request an increase in the size of the facility to an aggregate of $2.4 billion from $1.7 billion by either commitments from new lenders or increased commitments from existing lenders. The ONEOK Partners Credit Agreement is available for general partnership purposes. During the second quarter 2014, ONEOK Partners increased the size of its commercial paper program to $1.7 billion from $1.2 billion. In addition, in February 2015, ONEOK Partners notified its lenders of its intent to exercise its option to increase the capacity of the facility to an aggregate of $2.4 billion by increased commitments from existing lenders and/or commitments from one or more new lenders, which is pending lenders’ approval. Amounts outstanding under ONEOK Partners’ commercial paper program reduce the borrowing capacity under the ONEOK Partners Credit Agreement.
	The ONEOK Partners Credit Agreement contains provisions for an applicable margin rate and an annual facility fee, both of which adjust with changes in ONEOK Partners’ credit rating. Under the terms of the ONEOK Partners Credit Agreement, based on our current credit rating, borrowings, if any, will accrue at LIBOR plus 117.5 basis points, and the annual facility fee is 20 basis points. The ONEOK Partners Credit Agreement is guaranteed fully and unconditionally by ONEOK Partners’ wholly owned subsidiary, the Intermediate Partnership. Borrowings under ONEOK Partners Credit Agreement are nonrecourse to ONEOK.
	The ONEOK Partners Credit Agreement contains certain financial, operational and legal covenants that remained substantially the same with the amendment. Among other things, these covenants include maintaining a ratio of indebtedness to adjusted EBITDA (EBITDA, as defined in ONEOK Partners 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 ONEOK Partners consummates one or more acquisitions in which the aggregate purchase price is $25 million or more, the allowable ratio of indebtedness to adjusted EBITDA will increase to 5.5 to 1 for the quarter of the acquisition and the two following quarters. As a result of the West Texas LPG acquisition ONEOK Partners completed in the fourth quarter 2014, the allowable ratio of indebtedness to adjusted EBITDA increased to 5.5 to 1 through the second quarter 2015. If ONEOK Partners were to breach certain covenants in the ONEOK Partners Credit Agreement, amounts outstanding, if any, may become due and payable immediately. At December 31, 2014, ONEOK Partners’ ratio of indebtedness to adjusted EBITDA was 3.7 to 1, and ONEOK Partners was in compliance with all covenants under the ONEOK Partners Credit Agreement.
	Neither ONEOK nor ONEOK Partners guarantees the debt or other similar commitments of unaffiliated parties. ONEOK does not guarantee the debt, commercial paper or other similar commitments of ONEOK Partners, and ONEOK Partners does not guarantee the debt, commercial paper or other similar commitments of ONEOK.
	ONE Gas Credit Agreement - In December 2013, ONE Gas, while it was a wholly owned subsidiary of ONEOK, entered into the ONE Gas Credit Agreement, which became effective upon the separation of the natural gas distribution business on January 31, 2014.
	Upon completion of the separation on January 31, 2014, ONEOK’s obligations related to the ONE Gas Credit Agreement terminated.

LONGTERM_DEBT

LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2014
Long-term Debt, Unclassified [Abstract]
LONG-TERM DEBT
	I.	LONG-TERM DEBT
	All notes are senior unsecured obligations, ranking equally in right of payment with all of our existing and future unsecured senior indebtedness.  The following table sets forth our long-term debt for the periods indicated:
			December 31,			December 31,
			2014			2013
			(Thousands of dollars)
	ONEOK
	$400,000 at 5.2% due 2015		$	—		$	400,000
	$700,000 at 4.25% due 2022		547,397			700,000
	$100,000 at 6.5% due 2028		87,619			87,649
	$100,000 at 6.875% due 2028		100,000			100,000
	$400,000 at 6.0% due 2035		400,000			400,000
	Total ONEOK senior notes payable		1,135,016			1,687,649
	ONEOK Partners
	$650,000 at 3.25% due 2016		650,000			650,000
	$450,000 at 6.15% due 2016		450,000			450,000
	$400,000 at 2.0% due 2017		400,000			400,000
	$425,000 at 3.2% due 2018		425,000			425,000
	$500,000 at 8.625% due 2019		500,000			500,000
	$900,000 at 3.375 % due 2022		900,000			900,000
	$425,000 at 5.0 % due 2023		425,000			425,000
	$600,000 at 6.65% due 2036		600,000			600,000
	$600,000 at 6.85% due 2037		600,000			600,000
	$650,000 at 6.125% due 2041		650,000			650,000
	$400,000 at 6.2% due 2043		400,000			400,000
	Guardian Pipeline
	Average 7.88%, due 2022		59,557			67,208
	Total ONEOK Partners senior notes payable		6,059,557			6,067,208
	Total long-term notes payable		7,194,573			7,754,857
	Unamortized portion of terminated swaps		23,622			25,340
	Unamortized debt discount		(14,616		)	(15,890		)
	Current maturities		(10,650		)	(10,650		)
	Long-term debt		$	7,192,929		$	7,753,657
	The aggregate maturities of long-term debt outstanding for the years 2015 through 2019 are shown below:
			ONEOK			ONEOK			Guardian		Total
						Partners			Pipeline
			(Millions of dollars)
	2015		$	3		$	—		$	7.7	$	10.7
	2016		$	3		$	1,100.00		$	7.7	$	1,110.70
	2017		$	3		$	400		$	7.7	$	410.7
	2018		$	3		$	425		$	7.7	$	435.7
	2019		$	3		$	500		$	7.7	$	510.7
	Additionally, our senior notes due 2028 (6.5 percent) are callable at par at our option from now until maturity.
	ONE Gas Debt Issuance - In January 2014, ONE Gas, which at the time was our wholly owned subsidiary, completed a private placement of three series of senior notes aggregating $1.2 billion, consisting of $300 million of five-year senior notes at 2.07 percent; $300 million of 10-year senior notes at 3.61 percent; and $600 million of 30-year senior notes at 4.658 percent. ONE Gas received approximately $1.19 billion from the offering, net of issuance costs. Our obligations related to the ONE Gas Senior Notes terminated in connection with the completion of the separation of ONE Gas.
	ONEOK Debt Repayment - ONE Gas made a cash payment to ONEOK of approximately $1.13 billion from the proceeds of the ONE Gas senior notes offering. In February 2014, we retired approximately $152.5 million of the 4.25 percent senior notes due 2022 through a tender offer. The total amount paid, including fees and other charges, was approximately $150 million.
	In February 2014, we called our $400 million, 5.2 percent senior notes due in 2015. The full repayment occurred in March 2014 and totaled $430.1 million, including accrued but unpaid interest to the redemption date. We recorded a loss on extinguishment of $24.8 million related to the debt retirements, which is included in other expense in our Consolidated Statements of Income.
	ONEOK Debt Issuance - In January 2012, we completed an underwritten public offering of $700 million, 4.25 percent senior notes due 2022. The net proceeds from the offering, after deducting underwriting discounts and offering expenses, of approximately $694.3 million were used to repay amounts outstanding under our commercial paper program and for general corporate purposes.
	ONEOK Debt Covenants - The indentures governing ONEOK’s senior notes due 2028 (6.5 percent and 6.875 percent) include an event of default upon acceleration of other indebtedness of $15 million or more, and the indentures governing the senior notes due 2022 and 2035 include an event of default upon the 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 the outstanding senior notes due 2022, 2028 and 2035 to declare those senior notes immediately due and payable in full.
	ONEOK may redeem the senior notes due 2028 (6.875 percent) and 2035, in whole or in part, at any time prior to their maturity at a redemption price equal to the principal amount, plus accrued and unpaid interest and a make-whole premium. ONEOK may redeem the senior notes due 2028 (6.5 percent), in whole or in part, at any time prior to their maturity at a redemption price equal to the principal amount, plus accrued and unpaid interest.  ONEOK may redeem the remaining balance of its 4.25 percent senior notes due 2022 at a redemption price equal to the principal amount, plus accrued and unpaid interest, starting three months before the maturity date.  Prior to this date, ONEOK may redeem these senior notes on the same basis as its other senior notes due 2028 (6.875 percent) and 2035.  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.  ONEOK’s senior notes due 2022, 2028 and 2035 are senior unsecured obligations, ranking equally in right of payment with all of ONEOK’s existing and future unsecured senior indebtedness.
	ONEOK Partners’ Debt Issuance and Maturities - In September 2013, ONEOK Partners 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 its commercial paper program, and the balance was used for general partnership purposes, including but not limited to capital expenditures.
	In September 2012, ONEOK Partners 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 its commercial paper program, and the balance was used for general partnership purposes, including but not limited to capital expenditures.
	ONEOK Partners repaid its $350 million, 5.9 percent senior notes at maturity in April 2012 with a portion of the proceeds from its March 2012 equity offering.
	ONEOK Partners’ Debt Covenants - ONEOK Partners senior notes are governed by an indenture, dated as of September 25, 2006, between ONEOK Partners 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 ONEOK Partners’ ability to place liens on its property or assets and to sell and lease back its 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 ONEOK Partners’ outstanding senior notes to declare those notes immediately due and payable in full.
	ONEOK Partners may redeem its senior notes due 2016 (6.15 percent), 2019, 2036 and 2037, in whole or in part, at any time prior to their maturity at a redemption price equal to the principal amount, plus accrued and unpaid interest and a make-whole premium.  The redemption price will never be less than 100 percent of the principal amount of the respective note plus accrued and unpaid interest to the redemption date.
	ONEOK Partners may redeem its senior notes due 2017 and its senior notes due 2022 at par starting one month and three months, respectively, before their maturity dates. ONEOK Partners may redeem its senior notes due 2016 (3.25 percent) and 2041 at a redemption price equal to the principal amount, plus accrued and unpaid interest, starting one month and six months, respectively, before their maturity dates. Prior to these dates, ONEOK Partners may redeem these senior 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. ONEOK Partners may redeem its senior notes due 2018, 2023, and 2043 at par, plus accrued and unpaid interest to the redemption date, starting one month, three months, and six months, respectively, before their maturity dates. Prior to these dates, ONEOK Partners 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.
	ONEOK Partners’ senior notes are senior unsecured obligations, ranking equally in right of payment with all of ONEOK Partners’ existing and future unsecured senior indebtedness, and are structurally subordinate to any of the existing and future debt and other liabilities of any nonguarantor subsidiaries.  ONEOK Partners’ senior notes are nonrecourse to ONEOK.
	ONEOK Partners’ Debt Guarantee - ONEOK Partners’ senior notes are guaranteed fully and unconditionally on a senior unsecured basis by the Intermediate Partnership. The Intermediate Partnership’s guarantee is full and unconditional, subject to certain customary automatic release provisions. The guarantee ranks equally in right of payment to all of the Intermediate Partnership’s existing and future unsecured senior indebtedness. ONEOK Partners, L.P. has no significant assets or operations other than its investment in the Intermediate Partnership, which is also consolidated. At December 31, 2014, the Intermediate Partnership held the equity of ONEOK Partners’ subsidiaries, as well as a 50 percent interest in Northern Border Pipeline. ONEOK Partners’ long-term debt is nonrecourse to ONEOK.
	Guardian Pipeline Senior Notes - These senior notes were issued under a master shelf agreement dated November 8, 2001, with certain financial institutions. Principal payments are due quarterly through 2022. These senior notes contain financial covenants that require the maintenance of certain ratios defined in the master shelf agreement based on Guardian Pipeline’s financial position and results of operations. Upon any breach of these covenants, all amounts outstanding under the master shelf agreement may become due and payable immediately. At December 31, 2014, Guardian Pipeline was in compliance with its financial covenants.
	Other - We amortize premiums, discounts and expenses incurred in connection with the issuance of long-term debt consistent with the terms of the respective debt instrument.

EQUITY

EQUITY	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
EQUITY
	J.	EQUITY
	Series A and B Convertible Preferred Stock - There are no shares of Series A or Series B Preferred Stock currently issued or outstanding.
	Common Stock - At December 31, 2014, we had approximately 363.0 million shares of authorized and unreserved common stock available for issuance.
	Dividends - Dividends paid totaled $443.8 million, $304.7 million and $262.0 million for 2014, 2013 and 2012, respectively. The following table sets forth the quarterly dividends per share declared and paid on our common stock for the periods indicated:
			Years Ended December 31,
			2014		2013		2012
	First Quarter		$	0.4	$	0.36	$	0.305
	Second Quarter		$	0.56	$	0.36	$	0.305
	Third Quarter		$	0.575	$	0.38	$	0.33
	Fourth Quarter		$	0.59	$	0.38	$	0.33
	Total		$	2.125	$	1.48	$	1.27
	Additionally, a quarterly dividend of $0.605 per share was declared in January 2015, payable in the first quarter 2015.
	Stock Repurchase Program - We executed a $150 million repurchase of approximately 3.4 million shares in September 2012 and did not repurchase any shares of our common stock in 2013 under a stock repurchase program that expired on December 31, 2013.
	See Note Q for a discussion of ONEOK Partners’ issuance of common units and distributions to noncontrolling interests.

ACCUMULATED_OTHER_COMPREHENSIV

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	12 Months Ended
	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
	K.	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
	The following table sets forth the balance in accumulated other comprehensive income (loss) for the periods indicated:
		Unrealized Gains				Unrealized				Pension and			Accumulated
		(Losses) on Energy				Holding Gains				Postretirement			Other
		Marketing and				(Losses)				Benefit Plan			Comprehensive
		Risk-Management				on Investment				Obligations (a) (b)			Income (Loss) (a)
		Assets/Liabilities (a)				Securities (a)
		(Thousands of dollars)
	1-Jan-13	$	(55,030	)		$	1,034			$	(162,802	)	$	(216,798	)
	Other comprehensive income (loss) before	8,842				(177		)		37,144			45,809
	reclassifications
	Amounts reclassified from accumulated other	3,020				—				45,982			49,002
	comprehensive income (loss)
	Other comprehensive income	11,862				(177		)		83,126			94,811
	(loss) attributable to ONEOK
	31-Dec-13	(43,168		)		857				(79,676		)	(121,987		)
	Other comprehensive income (loss) before	(16,225		)		98				(33,987		)	(50,114		)
	reclassifications
	Amounts reclassified from accumulated other	22,044				—				10,315			32,359
	comprehensive income (loss)
	Other comprehensive income	5,819				98				(23,672		)	(17,755		)
	(loss) attributable to ONEOK
	Transfer to ONE Gas	—				—				3,389			3,389
	31-Dec-14	$	(37,349	)		$	955			$	(99,959	)	$	(136,353	)
	(a) All amounts are presented net of tax.
	(b) Includes amounts related to supplemental executive retirement plan.
	The following table sets forth the effect of reclassifications from accumulated other comprehensive income (loss) on our Consolidated Statements of Income for the periods indicated:
	Details about Accumulated Other		Years Ended December 31,								Affected Line Item
	Comprehensive Income (Loss) Components										in the Consolidated
			2014				2013				Statements of Income
			(Thousands of dollars)
	Unrealized (gains) losses on energy marketing and
	risk-management assets/liabilities
	Commodity contracts		$	21,052			$	(1,689	)		Commodity sales revenues
	Interest-rate contracts		21,966				14,560				Interest expense
			43,018				12,871				Income before income taxes
			(8,977		)		(3,081		)		Income tax expense
			34,041				9,790				Income from continuing operations
			7,682				(1,864		)		Income (loss) from discontinued
											operations
			41,723				7,926				Net income
	Noncontrolling interest		19,679				4,906				Less: Net income attributable to
											noncontrolling interest
			$	22,044			$	3,020			Net income attributable to ONEOK
	Pension and postretirement benefit plan obligations (a)
	Amortization of net loss		$	15,914			$	21,407
	Amortization of unrecognized prior service cost		(1,469		)		(1,560		)
	Amortization of unrecognized net asset at adoption		—				49
			14,445				19,896				Income before income taxes
			(5,778		)		(7,958		)		Income tax expense
			8,667				11,938				Income from continuing operations
			1,648				34,044				Income from discontinued operations
			$	10,315			$	45,982			Net income attributable to ONEOK
	Total reclassifications for the period attributable to ONEOK		$	32,359			$	49,002			Net income attributable to ONEOK
	(a) These components of accumulated other comprehensive income (loss) are included in the computation of net periodic benefit cost. See Note N for additional detail of our net periodic benefit cost.

EARNINGS_PER_SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
EARNINGS PER SHARE
	L.	EARNINGS PER SHARE
	The following tables set forth the computation of basic and diluted EPS from continuing operations for the periods indicated:
			Year Ended December 31, 2014
			Income		Shares	Per Share
						Amount
			(Thousands, except per share amounts)
	Basic EPS from continuing operations
	Income from continuing operations attributable to ONEOK available for		$	319,714	209,391	$	1.53
	common stock
	Diluted EPS from continuing operations
	Effect of options and other dilutive securities		—		1,036
	Income from continuing operations attributable to ONEOK available for		$	319,714	210,427	$	1.52
	common stock and common stock equivalents
			Year Ended December 31, 2013
			Income		Shares	Per Share
						Amount
			(Thousands, except per share amounts)
	Basic EPS from continuing operations
	Income from continuing operations attributable to ONEOK available for		$	278,662	206,044	$	1.35
	common stock
	Diluted EPS from continuing operations
	Effect of options and other dilutive securities		—		3,651
	Income from continuing operations attributable to ONEOK available for		$	278,662	209,695	$	1.33
	common stock and common stock equivalents
			Year Ended December 31, 2012
			Income		Shares	Per Share
						Amount
			(Thousands, except per share amounts)
	Basic EPS from continuing operations
	Income from continuing operations attributable to ONEOK available for		$	294,837	206,140	$	1.43
	common stock
	Diluted EPS from continuing operations
	Effect of options and other dilutive securities		—		4,570
	Income from continuing operations attributable to ONEOK available for		$	294,837	210,710	$	1.4
	common stock and common stock equivalents
	There were no option shares excluded from the calculation of diluted earnings per share for 2014, 2013 and 2012.

SHAREBASED_PAYMENTS

SHARE-BASED PAYMENTS	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
SHARE-BASED PAYMENTS
	M.	SHARE-BASED PAYMENTS
	The ONEOK, Inc. Equity Compensation Plan (ECP) and the ONEOK, Inc. Long-Term Incentive Plan (LTIP) provide for the granting of stock-based compensation, including incentive stock options, nonstatutory stock options, stock bonus awards, restricted stock awards, restricted stock-unit awards, performance stock awards and performance-unit awards to eligible employees and the granting of stock awards to nonemployee directors. We have reserved 10.0 million and 15.6 million shares of common stock for issuance under the ECP and LTIP, respectively. At December 31, 2014, we had approximately 2.8 million and 1.0 million shares available for issuance under the ECP and LTIP, respectively, which reflect shares issued and estimated shares expected to be issued upon vesting of outstanding awards granted under these plans, less forfeitures.  These plans allow for the deferral of awards granted in stock or cash, in accordance with Internal Revenue Code section 409A requirements.
	Restricted Stock Units - We have granted restricted stock units to key employees that vest over a three-year period and entitle the grantee to receive shares of our common stock.  Restricted stock unit awards are measured at fair value as if they were vested and issued on the grant date, reduced by expected dividend payments and adjusted for estimated forfeitures.  No dividends were paid prior to vesting on the restricted stock units granted prior to 2013.  Beginning in 2013, restricted stock unit awards granted accrue dividend equivalents in the form of additional restricted stock units prior to vesting. Compensation expense is recognized on a straight-line basis over the vesting period of the award.
	Performance-Unit Awards - We have granted performance-unit awards to key employees.  The shares of our common stock underlying the performance units vest at the expiration of a period determined by the Executive Compensation Committee if certain performance criteria are met by the company.  Outstanding performance units vest at the expiration of a three-year period. Upon vesting, a holder of outstanding performance units is entitled to receive a number of shares of our common stock equal to a percentage (0 percent to 200 percent) of the performance units granted, based on our total shareholder return over the vesting period, compared with the total shareholder return of a peer group of other energy companies over the same period. Compensation expense is recognized on a straight-line basis over the period of the award.
	If paid, the outstanding performance unit awards entitle the grantee to receive the grant in shares of our common stock. Our outstanding performance unit awards are equity awards with a market-based condition, which results in the compensation cost for these awards being recognized over the requisite service period, provided that the requisite service period is fulfilled, regardless of when, if ever, the market condition is satisfied. The fair value of these performance units was estimated on the grant date based on a Monte Carlo model. No dividends were paid prior to vesting on performance stock units granted prior to 2013. Beginning in 2013, performance stock unit awards granted accrue dividend equivalents in the form of additional performance units prior to vesting. The compensation expense on these awards only will be adjusted for changes in forfeitures.
	Options - No stock options have been granted since 2003. Stock option activity was not material in 2013 and 2012. All previously issued stock options expired or were exercised as of February 2013.
	Stock Compensation Plan for Non-Employee Directors
	The ONEOK, Inc. Stock Compensation Plan for Non-Employee Directors (the DSCP) provides for the granting of stock options, stock bonus awards, including performance-unit awards, restricted stock awards and restricted stock unit awards. Under the DSCP, these awards may be granted by the Executive Compensation Committee at any time, until grants have been made for all shares authorized under the DSCP.  We have reserved a total of 1.4 million shares of common stock for issuance under the DSCP, and at December 31, 2014, we had approximately 1.0 million shares available for issuance under the plan. The maximum number of shares of common stock that can be issued to a participant under the DSCP during any year is 40,000. No performance unit awards or restricted stock awards have been made to nonemployee directors under the DSCP.
	General
	For all awards outstanding, we used a 3 percent forfeiture rate based on historical forfeitures under our share-based payment plans. We primarily use treasury stock to satisfy our share-based payment obligations.
	Compensation cost expensed for our share-based payment plans described above was $21.3 million, $34.0 million and $26.9 million during 2014, 2013 and 2012, respectively, which is net of tax benefits of $4.9 million, $12.2 million and $9.8 million, respectively. Compensation cost expensed included in income from continuing operations for each respective year was $18.6 million, $21.1 million, and $15.1 million, net of tax benefits. Capitalized share-based compensation cost was not material for 2014, 2013 and 2012.
	Cash received from the exercise of awards under all share-based payment arrangements was not material for 2014, 2013 and 2012.  The tax benefit realized for the anticipated tax deductions of the exercise of share-based payment arrangements was not material for 2014, 2013 and 2012.
	Impact of ONE Gas Separation on Stock Compensation Plans
	In connection with the separation of our former natural gas distribution business on January 31, 2014, ONEOK entered into an Employee Matters Agreement with ONE Gas, which provides that employees of ONE Gas no longer participate in stock compensation plans sponsored or maintained by ONEOK. Pursuant to the Employee Matters Agreement, we made certain adjustments to the number of our share-based compensation awards, with the intention of preserving the intrinsic value of each award immediately prior to the separation. Unless otherwise indicated, information presented below is on a pre-separation basis and reflects employees and costs of both continuing and discontinued operations.
	Restricted Stock Unit Activity
	As of December 31, 2014, we had $7.9 million of total unrecognized compensation cost related to our nonvested restricted stock unit awards, which is expected to be recognized over a weighted-average period of 1.8 years.  The following tables set forth activity and various statistics for our restricted stock unit awards:
			Number of			Weighted
			Shares			Average Price
	Nonvested December 31, 2013		776,596			$	35.27
	Granted		145,342			$	58.23
	Released to participants		(366,302	)		$	29.07
	Forfeited		(28,822	)		$	43.96
	Awards surrendered as a result of the separation		(124,263	)		$	42.9
	Awards granted in conversion as a result of the separation		45,381			$	—
	Nonvested December 31, 2014		447,932			$	41.54
			2014				2013		2012
	Weighted-average grant date fair value (per share)		$	58.23			$	47.46	$	36.65
	Fair value of shares granted (thousands of dollars)		$	8,463			$	7,940	$	11,030
	Restricted stock units held by an employee who separated from ONEOK and became an employee of ONE Gas were surrendered as a result of the separation. The number of restricted stock units held by employees who remained with ONEOK following the separation was adjusted by issuing additional units to preserve the intrinsic value of the units immediately prior to the separation.
	Performance-Unit Activity
	As of December 31, 2014, we had $13.6 million of total unrecognized compensation cost related to the nonvested performance-unit awards, which is expected to be recognized over a weighted-average period of 1.7 years.  The following tables set forth activity and various statistics related to the performance-unit awards and the assumptions used in the valuations of the 2014, 2013 and 2012 grants at the grant date:
			Number of			Weighted
			Units			Average Price
	Nonvested December 31, 2013		1,652,145			$	41.1
	Granted		186,436			$	64.75
	Released to participants		(743,897	)		$	34.68
	Forfeited		(53,927	)		$	48.99
	Awards surrendered as a result of the separation		(265,750	)		$	47.62
	Awards granted in conversion as a result of the separation		97,723			$	—
	Nonvested December 31, 2014		872,730			$	44.55
			2014		2013		2012
	Volatility (a)		25.48%		22.27%		27.00%
	Dividend Yield		2.63%		3.04%		2.86%
	Risk-free Interest Rate		0.69%		0.42%		0.38%
	(a) - Volatility was based on historical volatility over three years using daily stock price observations.
			2014				2013		2012
	Weighted-average grant date fair value (per share)		$	64.75			$	52.34	$	42.39
	Fair value of shares granted (thousands of dollars)		$	12,071			$	19,742	$	25,466
	Performance-unit awards held by employees who separated from ONEOK and became employees of ONE Gas were surrendered as a result of the separation. The number of performance unit awards held by employees who remained with ONEOK following the separation was adjusted by issuing additional units to preserve the intrinsic value of the performance units immediately prior to the separation.
	Employee Stock Purchase Plan
	We have reserved a total of 11.6 million shares of common stock for issuance under our ONEOK, Inc. Employee Stock Purchase Plan (the ESPP).  Subject to certain exclusions, all full-time employees are eligible to participate in the ESPP. Employees can choose to have up to 10 percent of their annual base pay withheld to purchase our common stock, subject to terms and limitations of the plan.  The Executive Compensation Committee may allow contributions to be made by other means, provided that in no event will contributions from all means exceed 10 percent of the employee’s annual base pay.  The purchase price of the stock is 85 percent of the lower of its grant date or exercise date market price.  Approximately 67 percent, 52 percent and 55 percent of employees participated in the plan in 2014, 2013 and 2012, respectively. Compensation expense for continuing operations for the ESPP was not material in 2014, 2013 and 2012. Under the plan, we sold 110,592 shares at $43.85 in 2014, 254,960 shares at $35.97 per share in 2013 and 256,490 shares at $35.97 per share in 2012.
	For those employees who separated from ONEOK and became employees of ONE Gas, their enrollment in the plan was terminated upon the separation. Employees who separated from ONEOK and became employees of ONE Gas received shares of ONEOK common stock at the end of the offering period based upon the contributions made while employed at ONEOK. There was no impact to enrollment for those employees who remained at ONEOK. The grant date market price for ONEOK stock was adjusted to reflect the impact of the distribution of ONE Gas shares.
	Employee Stock Award Program
	Under our Employee Stock Award Program, we issued, for no monetary consideration, to all eligible employees one share of our common stock when the per-share closing price of our common stock on the NYSE was for the first time at or above $13 per share.  The total number of shares of our common stock available for issuance under this program was 900,000.  Shares issued to employees under this program during 2014, 2013 and 2012 totaled 49,864, 63,975 and 42,467 respectively, and compensation expense related to the Employee Stock Award Plan was $2.1 million, $3.6 million and $1.9 million in 2014, 2013 and 2012, respectively.
	Deferred Compensation Plan for Non-Employee Directors
	The ONEOK, Inc. Nonqualified Deferred Compensation Plan for Non-Employee Directors provides our nonemployee directors the option to defer all or a portion of their compensation for their service on our Board of Directors. Under the plan, directors may elect either a cash deferral option or a phantom stock option. Under the cash deferral option, directors may defer the receipt of all or a portion of their annual retainer fees, plus accrued interest. Under the phantom stock option, directors may defer all or a portion of their annual retainer fees and receive such fees on a deferred basis in the form of shares of common stock under our Long-Term Incentive Plan or Equity Compensation Plan. Shares are distributed to nonemployee directors at the fair market value of our common stock at the date of distribution.
	Deferred shares associated with vested restricted stock unit awards or performance unit awards held by directors or employees were treated in the same manner as regular shareholders in connection with the ONE Gas separation, by crediting one deferred share of ONE Gas common stock for every four deferred shares of ONEOK common stock.

EMPLOYEE_BENEFIT_PLANS

EMPLOYEE BENEFIT PLANS	12 Months Ended
	Dec. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
EMPLOYEE BENEFIT PLANS
	N.	EMPLOYEE BENEFIT PLANS
	Retirement and Postretirement Benefit Plans
	Retirement Plans - We have a defined benefit pension plan covering employees hired before January 1, 2005. Employees hired after December 31, 2004, and employees who accepted a one-time opportunity to opt out of our pension plan are covered by our Profit-Sharing Plan. In addition, we have a supplemental executive retirement plan for the benefit of certain officers. No new participants in our supplemental executive retirement plan have been approved since 2005, and effective January 2014 the plan formally was closed to new participants. We fund our pension costs at a level needed to maintain or exceed the minimum funding levels required by the Employee Retirement Income Security Act of 1974, as amended, and the Pension Protection Act of 2006.
	Postretirement Benefit Plans - We sponsor health and welfare plans that provide postretirement medical and life insurance benefits to certain employees who retire with at least five years of service.  The postretirement medical plan is contributory based on hire date, age and years of service, with retiree contributions adjusted periodically, and contains other cost-sharing features such as deductibles and coinsurance.
	Obligations and Funded Status - The following tables set forth our pension and postretirement benefit plans benefit obligations and fair value of plan assets for our continuing operations for the periods indicated:
			Pension Benefits						Postretirement Benefits
			December 31,						December 31,
			2014			2013			2014			2013
	Change in Benefit Obligation		(Thousands of dollars)
	Benefit obligation, beginning of period		$	361,578		$	383,979		$	50,232		$	56,843
	Service cost		7,238			6,127			710			458
	Interest cost		18,324			15,626			2,433			1,164
	Plan participants’ contributions		—			—			1,537			730
	Actuarial loss (gain)		42,891			(32,120		)	6,822			(5,833		)
	Benefits paid		(12,101		)	(12,034		)	(4,815		)	(3,130		)
	Other adjustments		(3,749		)	—			(256		)	—
	Benefit obligation, end of period		414,181			361,578			56,663			50,232
	Change in Plan Assets
	Fair value of plan assets, beginning of period		274,936			243,525			28,626			24,147
	Actual return on plan assets		17,619			43,445			1,765			4,481
	Employer contributions		—			—			2,000			147
	Plan participants’ contributions		—			—			1,233			—
	Benefits paid		(12,101		)	(12,034		)	(3,968		)	(149		)
	Other adjustments		(2,886		)	—			(227		)	—
	Fair value of assets, end of period		277,568			274,936			29,429			28,626
	Balance at December 31		$	(136,613	)	$	(86,642	)	$	(27,234	)	$	(21,606	)
	Current liabilities		$	(4,634	)	$	(4,645	)	$	—		$	—
	Noncurrent liabilities		(131,979		)	(81,997		)	(27,234		)	(21,606		)
	Balance at December 31		$	(136,613	)	$	(86,642	)	$	(27,234	)	$	(21,606	)
	The table above includes the supplemental executive retirement plan obligation. ONEOK has investments included in Other assets on the Consolidated Balance Sheets, which totaled $82.4 million and $77.3 million at December 31, 2014 and 2013, respectively, for the purpose of funding the obligation. These assets are excluded from the table above as those are not assets of the supplemental executive retirement plan.
	In connection with the separation of the natural gas distribution business, ONEOK entered into an Employee Matters Agreement with ONE Gas, which provides that employees of ONE Gas no longer participate in benefit plans sponsored or maintained by ONEOK as of January 1, 2014. The ONEOK defined benefit pension plans and postretirement benefit plans transferred an allocable portion of assets and obligations related to those employees transferring as employees to ONE Gas to newly established trusts for the ONE Gas plans. This resulted in a decrease in ONEOK’s sponsored qualified and nonqualified pension and postretirement plan obligations of approximately $1.1 billion and a decrease in ONEOK’s sponsored pension and postretirement plan assets of approximately $1.0 billion. Additionally, as a result of the transfer of unrecognized losses to ONE Gas, ONEOK’s deferred income taxes and regulatory assets decreased approximately $86.0 million and $331.1 million, respectively. The accumulated benefit obligation for our pension plans for our continuing operations was $393.3 million and $343.2 million at December 31, 2014 and 2013, respectively.
	There are no plan assets expected to be withdrawn and returned to us in 2015.
	Components of Net Periodic Benefit Cost - The following tables set forth the components of net periodic benefit cost for our pension and postretirement benefit plans for our continuing operations for the periods indicated:
			Pension Benefits
			Years Ended December 31,
			2014			2013			2012
			(Thousands of dollars)
	Components of net periodic benefit cost
	Service cost		$	7,238		$	6,127		$	5,633
	Interest cost		18,324			15,626			17,205
	Expected return on assets		(19,526		)	(19,874		)	(20,595		)
	Amortization of prior service cost		193			239			252
	Amortization of net loss		15,078			19,016			14,403
	Net periodic benefit cost		$	21,307		$	21,134		$	16,898
			Postretirement Benefits
			Years Ended December 31,
			2014			2013			2012
			(Thousands of dollars)
	Components of net periodic benefit cost
	Service cost		$	710		$	458		$	414
	Interest cost		2,433			1,164			1,158
	Expected return on assets		(2,163		)	(1,218		)	(891		)
	Amortization of unrecognized net asset at adoption		—			49			169
	Amortization of prior service cost		(1,662		)	(1,799		)	(2,493		)
	Amortization of net loss		836			2,391			2,975
	Net periodic benefit cost		$	154		$	1,045		$	1,332
	Other Comprehensive Income (Loss) - The following tables set forth the amounts recognized in other comprehensive income (loss) related to our pension benefits and postretirement benefits for our continuing operations for the periods indicated:
			Pension Benefits
			Years Ended December 31,
			2014			2013			2012
			(Thousands of dollars)
	Net gain (loss) arising during the period		$	(49,293	)	$	51,874		$	(29,625	)
	Amortization of prior service credit		193			239			252
Amortization of net loss		15,078			19,016			14,403
Deferred income taxes		13,609			(28,452		)	5,988
Total recognized in other comprehensive income (loss)		$	(20,413	)	$	42,677		$	(8,982	)
		Postretirement Benefits
		Years Ended December 31,
		2014			2013			2012
		(Thousands of dollars)
Net gain (loss) arising during the period		$	(7,220	)	$	9,096		$	(2,423	)
Amortization of transition obligation		—			49			169
Amortization of prior service cost		(1,662		)	(1,799		)	(2,493		)
Amortization of net loss		836			2,391			2,975
Deferred income taxes		3,218			(3,895		)	709
Total recognized in other comprehensive income (loss)		$	(4,828	)	$	5,842		$	(1,063	)
The table below sets forth the amounts in accumulated other comprehensive income (loss) that had not yet been recognized as components of net periodic benefit expense for our continuing operations for the periods indicated:
		Pension Benefits						Postretirement Benefits
		December 31,						December 31,
		2014			2013			2014			2013
		(Thousands of dollars)
Prior service credit (cost)		$	(94	)	$	(287	)	$	6,873		$	8,535
Accumulated loss		(156,985		)	(122,770		)	(16,396		)	(10,012		)
Accumulated other comprehensive loss		(157,079		)	(123,057		)	(9,523		)	(1,477		)
Deferred income taxes		62,832			49,223			3,811			591
Accumulated other comprehensive loss, net of tax		$	(94,247	)	$	(73,834	)	$	(5,712	)	$	(886	)
The following table sets forth the amounts recognized in accumulated comprehensive income (loss) expected to be recognized as components of net periodic benefit expense for our continuing operations in the next fiscal year.
		Pension			Postretirement
		Benefits			Benefits
Amounts to be recognized in 2015		(Thousands of dollars)
Prior service (credit) cost		$	94		$	(1,662	)
Net loss		$	15,981		$	1,743
Actuarial Assumptions - The following table sets forth the weighted-average assumptions used to determine benefit obligations for pension and postretirement benefits for the periods indicated:
		Pension Benefits			Postretirement Benefits
		December 31,			December 31,
		2014		2013	2014		2013
Discount rate		4.50%		5.25%	4.25%		5.00%
Compensation increase rate		3.15%		3.20%	3.15%		3.20%
The following table sets forth the weighted-average assumptions used to determine net periodic benefit costs for the periods indicated:
		Years Ended December 31,
		2014		2013	2012
Discount rate - pension plans		5.25%		4.25%	5.00%
Discount rate - postretirement plans		5.00%		4.00%	5.00%
Expected long-term return on plan assets		7.75%		8.25%	8.25%
Compensation increase rate		3.20%		3.50%	3.80%
We determine our overall expected long-term rate of return on plan assets, based on our review of historical returns and economic growth models.
We determine our discount rates annually.  We estimate our discount rate based upon a comparison of the expected cash flows associated with our future payments under our pension and postretirement obligations to a hypothetical bond portfolio created using high-quality bonds that closely match expected cash flows.  Bond portfolios are developed by selecting a bond for each of the next 60 years based on the maturity dates of the bonds.  Bonds selected to be included in the portfolios are only those rated by Moody’s as AA- or better and exclude callable bonds, bonds with less than a minimum issue size, yield outliers and other filtering criteria to remove unsuitable bonds.
Health Care Cost Trend Rates - The following table sets forth the assumed health care cost-trend rates for the periods indicated:
		2014		2013
Health care cost-trend rate assumed for next year		4.0% - 7.75%		4.0% - 8.25%
Rate to which the cost-trend rate is assumed to decline		4.0% - 5.0%		5.00%
(the ultimate trend rate)
Year that the rate reaches the ultimate trend rate		2022		2022
Assumed health care cost-trend rates have an impact on the amounts reported for our health care plans.  A one percentage point change in assumed health care cost-trend rates would have the following effects on our continuing operations:
		One Percentage			One Percentage
		Point Increase			Point Decrease
		(Thousands of dollars)
Effect on total of service and interest cost		$	74		$	(67	)
Effect on postretirement benefit obligation		$	1,131		$	(1,025	)
Plan Assets - Our investment strategy is to invest plan assets in accordance with sound investment practices that emphasize long-term fundamentals.  The goal of this strategy is to maximize investment returns while managing risk in order to meet the plan’s current and projected financial obligations. The investment policy follows a glide path approach toward liability-driven investing that shifts a higher portfolio weighting to fixed income as the plan's funded status increases.  The purpose of liability-driven investing is to structure the asset portfolio to more closely resemble the pension liability and thereby more effectively hedge against changes in the liability. The plan’s current investments include a diverse blend of various domestic and international equities, investments in various classes of debt securities, insurance contracts and venture capital.  The target allocation for the assets of our pension plan as of December 31, 2014, is as follows:
U.S. large-cap equities		37	%
Aggregate bonds		24	%
Developed foreign large-cap equities		10	%
Alternative investments		8	%
Mid-cap equities		6	%
Emerging markets equities		5	%
Small-cap equities		4	%
High-yield bonds		3	%
Developed foreign bonds		2	%
Emerging market bonds		1	%
Total		100	%
As part of our risk management for the plans, minimums and maximums have been set for each of the asset classes listed above. All investment managers for the plan are subject to certain restrictions on the securities they purchase and, with the exception of indexing purposes, are prohibited from owning our stock.
The following tables set forth our pension benefits and postretirement benefits plan assets by fair value category for our continuing operations as of the measurement date:
		Pension Benefits
		31-Dec-14
Asset Category		Level 1			Level 2			Level 3			Total
		(Thousands of dollars)
Investments:
Equity securities (a)		$	160,421		$	15,315		$	—		$	175,736
Government obligations		—			21,044			—			21,044
Corporate obligations (b)		—			55,948			—			55,948
Cash and money market funds (c)		4,610			—			—			4,610
Other investments (d)		—			—			20,230			20,230
Total assets		$	165,031		$	92,307		$	20,230		$	277,568
(a) - This category represents securities of the respective market sector from diverse industries.
(b) - This category represents bonds from diverse industries.
(c) - This category is primarily money market funds.
(d) - This category represents alternative investments.
		Pension Benefits
		31-Dec-13
Asset Category		Level 1			Level 2			Level 3			Total
		(Thousands of dollars)
Investments:
Equity securities (a)		$	178,329		$	15,809		$	—		$	194,138
Government obligations		—			29,160			—			29,160
Corporate obligations (b)		—			25,005			—			25,005
Cash and money market funds (c)		7,258			—			—			7,258
Other investments (d)		—			—			19,375			19,375
Total assets		$	185,587		$	69,974		$	19,375		$	274,936
(a) - This category represents securities of the respective market sector from diverse industries.
(b) - This category represents bonds from diverse industries.
(c) - This category is primarily money market funds.
(d) - This category represents alternative investments.
		Postretirement Benefits
		31-Dec-14
Asset Category		Level 1			Level 2			Level 3			Total
		(Thousands of dollars)
Investments:
Equity securities (a)		$	1,599		$	—		$	—		$	1,599
Cash and money market funds		1,644			—			—			1,644
Insurance and group annuity contracts		—			26,186			—			26,186
Total assets		$	3,243		$	26,186		$	—		$	29,429
(a) - This category represents securities of the respective market sector from diverse industries.
		Postretirement Benefits
		31-Dec-13
Asset Category		Level 1			Level 2			Level 3			Total
		(Thousands of dollars)
Investments:
Equity securities (a)		$	1,464		$	—		$	—		$	1,464
Cash and money market funds (b)		1,300			—			—			1,300
Insurance and group annuity contracts		—			25,862			—			25,862
Total assets		$	2,764		$	25,862		$	—		$	28,626
(a) - This category represents securities of the respective market sector from diverse industries.
(b) - This category represents money market funds.
The following tables set forth the reconciliation of Level 3 fair value measurements of our pension plan for our continuing operations for the periods indicated:
		Pension Benefits
		Years Ended December 31,
		2014			2013
		(Thousands of dollars)
Fair value of plan assets at beginning of period		$	19,375		$	17,842
Net realized and unrealized gains (losses)		855			1,533
Fair value of plan assets at end of period		$	20,230		$	19,375
Contributions - During 2014, we made no contributions to our defined benefit pension plan and $2.0 million in contributions to our postretirement benefit plans for our continuing operations.  At December 31, 2014, we expect to make $1.5 million in contributions to our defined benefit pension plan and postretirement plans in 2015.
Pension and Postretirement Benefit Payments - Benefit payments for our pension and postretirement benefit plans for the period ending December 31, 2014, were $12.1 million and $4.8 million, respectively.  The following table sets forth the pension benefits and postretirement benefits payments expected to be paid in 2015-2024 for our continuing operations:
		Pension			Postretirement
		Benefits			Benefits
Benefits to be paid in:		(Thousands of dollars)
2015		$	13,928		$	2,865
2016		$	14,914		$	3,011
2017		$	15,887		$	3,260
2018		$	16,979		$	3,442
2019		$	18,025		$	3,601
2020 through 2024		$	104,652		$	19,023
The expected benefits to be paid are based on the same assumptions used to measure our benefit obligation at December 31, 2014, and include estimated future employee service.
Other Employee Benefit Plans
401(k) Plan - We have a 401(k) Plan covering all employees, and employee contributions are discretionary.  We match 100 percent of employee contributions up to 6 percent of each participant’s eligible compensation, subject to certain limits. Our contributions made to the plan for our continuing operations were $9.3 million, $8.4 million and $7.6 million in 2014, 2013 and 2012, respectively.
Profit-Sharing Plan - We have a profit-sharing plan (Profit-Sharing Plan) for all employees hired after December 31, 2004. Employees who were employed prior to January 1, 2005, were given a one-time opportunity to make an irrevocable election to participate in the Profit-Sharing Plan and not accrue any additional benefits under our defined benefit pension plan after December 31, 2004. We plan to make a contribution to the Profit-Sharing Plan each quarter equal to 1 percent of each participant’s eligible compensation during the quarter. Additional discretionary employer contributions may be made at the end of each year. Employee contributions are not allowed under the plan.  Our contributions made to the plan for our continuing operations were $4.6 million, $3.4 million and $4.4 million in 2014, 2013 and 2012, respectively.
Nonqualified Deferred Compensation Plan - The Nonqualified Deferred Compensation Plan provides select employees, as approved by our Chief Executive Officer, with the option to defer portions of their compensation and provides nonqualified deferred compensation benefits that are not available due to limitations on employer and employee contributions to qualified defined contribution plans under the federal tax laws.  Our contributions made to the plan were not material in 2014, 2013 and 2012.

INCOME_TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
INCOME TAXES
	O.	INCOME TAXES
	The following table sets forth our provisions for income taxes for the periods indicated:
			Years Ended December 31,
			2014			2013			2012
	Current income taxes		(Thousands of dollars)
	Federal		$	10,180		$	(9,531	)	$	41,246
	State		3,311			1,812			1,798
	Total current income taxes from continuing operations		13,491			(7,719		)	43,044
	Deferred income taxes
	Federal		152,352			156,818			134,208
	State		(14,685		)	16,981			3,506
	Total deferred income taxes from continuing operations		137,667			173,799			137,714
	Total provision for income taxes from continuing operations		151,158			166,080			180,758
	Discontinued operations		7,567			(2,698		)	43,186
	Total provision for income taxes		$	158,725		$	163,382		$	223,944
	The following table is a reconciliation of our income tax provision from continuing operations for the periods indicated:
			Years Ended December 31,
			2014			2013			2012
			(Thousands of dollars)
	Income from continuing operations before income taxes		$	819,873		$	755,170		$	858,506
	Less: Net income attributable to noncontrolling interest		349,001			310,428			382,911
	Income from continuing operations attributable to ONEOK before		470,872			444,742			475,595
	income taxes
	Federal statutory income tax rate		35		%	35		%	35		%
	Provision for federal income taxes		164,805			155,660			166,458
	State income taxes, net of federal tax benefit		14,278			12,102			7,908
	State deferred tax rate change, net of valuation allowance		(25,653		)	—			—
	Other, net		(2,272		)	(1,682		)	6,392
	Income tax provision from continuing operations		$	151,158		$	166,080		$	180,758
	The following table sets forth the tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and liabilities for our continuing operations for the periods indicated:
			December 31,			December 31,
			2014			2013
	Deferred tax assets		(Thousands of dollars)
	Employee benefits and other accrued liabilities		$	81,905		$	78,136
	Federal net operating loss		80,851			12,484
	State net operating loss and benefits		38,429			38,322
	Derivative instruments		22,511			22,872
	Other		13,133			7,582
	Total deferred tax assets		236,829			159,396
	Valuation allowance for state tax credits
	Carryforward expected to expire prior to utilization		(8,807		)	—
	Net deferred tax assets		228,022			159,396
	Deferred tax liabilities
	Excess of tax over book depreciation		89,379			60,725
	Investment in partnerships		1,466,456			1,217,605
	Regulatory assets		1,961			2,625
	Total deferred tax liabilities		1,557,796			1,280,955
	Net deferred tax liabilities before discontinued operations		1,329,774			1,121,559
	Discontinued operations		(35,559		)	775,862
	Net deferred tax liabilities		$	1,294,215		$	1,897,421
	We have changed our presentation of deferred tax assets related to timing differences arising from balances in accumulated other comprehensive income to separately present amounts from pension and other postretirement benefit plans and derivative financial instruments. Prior periods have been recast to conform to the current year presentation.
	Our income tax payable balance at December 31, 2014, was not material. We had income taxes receivable of approximately $24.7 million at December 31, 2013.
	Tax benefits related to net operating loss (NOL) carryforwards will begin expiring in 2032. We believe that it is more likely than not that the tax benefits of the net operating loss carryforwards will be utilized prior to their expirations; therefore, no valuation allowance is necessary.
	Deferred tax assets related to tax benefits of employee share-based compensation have been reduced for performance share units and restricted share units that vested in periods in which ONEOK was in an NOL position. This vesting resulted in tax deductions in excess of previously recorded benefits based on the performance share unit and restricted share unit value at the time of grant. Although these additional tax benefits are reflected in NOL carryforwards in the tax return, the additional tax benefit is not recognized until the deduction reduces taxes payable. A portion of the tax benefit does not reduce ONEOK’s current taxes payable due to NOL carryforwards; accordingly, these tax benefits are not reflected in ONEOK’s NOLs in deferred tax assets. Cumulative tax benefits included in NOL carryforwards but not reflected in deferred tax assets were $54.3 million as of December 31, 2014, and $35.9 million as of December 31, 2013.
	ONE Gas Separation - ONE Gas was included in our consolidated federal and state income tax returns through the date of the separation. Any changes to the estimated ONE Gas taxes at the separation date will result in a reimbursement between us and ONE Gas under the terms of the tax sharing agreement. We are principally responsible for managing any income tax audits by the various tax jurisdictions for periods prior to the separation.
	Deferred tax liabilities and deferred income tax expense were reduced by $34.6 million in the first quarter 2014 primarily due to a reduction in our estimate of the effective state income tax rate to reflect a change in the mix of taxable income in the states in which we now operate, resulting from the separation of our former natural gas distribution business and the wind down of our energy services business. We also recorded a valuation allowance of $8.2 million in the first quarter 2014 for state tax credits as it is more likely than not that we will not be able to utilize these credits as a result of the separation of our former natural gas distribution business and the wind down of our energy services business. Together, these adjustments resulted in a net $26.4 million reduction in deferred tax liabilities and deferred income tax expense.

UNCONSOLIDATED_AFFILIATES

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

ONEOK_PARTNERS_ONEOK_PARTNERS_

ONEOK PARTNERS ONEOK PARTNERS (Notes)	12 Months Ended
	Dec. 31, 2014
Related Party Transaction [Line Items]
Related Party Transactions Disclosure [Text Block]
	Q.	ONEOK PARTNERS
	Ownership Interest in ONEOK Partners - Our ownership interest in ONEOK Partners is shown in the table below as of December 31, 2014:
	General partner interest		2	%
	Limited partner interest (a)		35.8	%
	Total ownership interest		37.8	%
	(a) - Represents 19.8 million common units and approximately 73.0 million Class B units, which are convertible, at our option, into common units.
	Equity Issuances - In May 2014, ONEOK Partners completed an underwritten public offering of approximately 13.9 million common units at a public offering price of $52.94 per common unit, generating net proceeds of approximately $714.5 million. In conjunction with this issuance, we contributed approximately $15.0 million in order to maintain our 2 percent general partner interest in ONEOK Partners. ONEOK Partners used the proceeds to repay commercial paper, fund its capital expenditures and for general partnership purposes.
	ONEOK Partners has an “at-the-market” equity program for the offer and sale from time to time of its common units. In November 2014, ONEOK Partners entered into an equity distribution agreement in the aggregate amount of $650 million. The program allows ONEOK Partners to offer and sell its common units at prices it deems 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 ONEOK Partners and the sales agent. ONEOK Partners is under no obligation to offer and sell common units under the program. During 2014, ONEOK Partners utilized the remainder of its previous equity distribution agreement in the aggregate amount of $300 million. At December 31, 2014, ONEOK Partners had approximately $514 million of registered common units available for issuance under its “at-the-market” equity program.
	During the year ended December 31, 2014, ONEOK Partners sold approximately 7.9 million common units through its “at-the-market” equity program. The net proceeds, including our contribution to maintain our 2 percent general partner interest in ONEOK Partners, were approximately $402.1 million, which were used for general partnership purposes.
	As a result of these transactions, our aggregate ownership interest in ONEOK Partners decreased to 37.8 percent at December 31, 2014, from 41.2 percent at December 31, 2013.
	In August 2013, ONEOK Partners 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 ONEOK Partners. ONEOK Partners used a portion of the proceeds from its August 2013 equity issuance to repay amounts outstanding under its commercial paper program and the balance was used for general partnership purposes.
	During the year ended December 31, 2013, ONEOK Partners sold approximately 681 thousand common units through its “at-the-market” equity program. The net proceeds, including our contribution to maintain our 2 percent general partner interest in ONEOK Partners, were approximately $36.1 million, which were used for general partnership purposes.
	In March 2012, ONEOK Partners 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. ONEOK Partners also sold 8.0 million common units to us 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 ONEOK Partners. ONEOK Partners used the net proceeds from the issuances to repay $295 million of borrowings under its commercial paper program, to repay amounts on the maturity of its $350 million, 5.9 percent senior notes due in April 2012 and for other general partnership purposes, including capital expenditures. As a result of these transactions, our aggregate ownership interest in ONEOK Partners increased to 43.4 percent in December 31, 2012, from 42.8 percent at December 31, 2011.
	We account for the difference between the carrying amount of our investment in ONEOK Partners and the underlying book value arising from issuance of common units by ONEOK Partners as an equity transaction.  If ONEOK Partners issues common units at a price different than our carrying value per unit, we account for the premium or deficiency as an adjustment to paid-in capital.  As a result of ONEOK Partners’ issuance of common units, we recognized an increase to paid-in capital of approximately $156.1 million, net of taxes, in 2014 and an increase to paid-in capital of approximately $87.3 million, net of taxes, in 2013, and a decrease to paid-in capital of approximately $51.1 million, net of taxes, in 2012.
	Cash Distributions - We receive distributions from ONEOK Partners on our common and Class B units and our 2 percent general partner interest, which includes our incentive distribution rights. Under ONEOK Partners’ partnership agreement, as amended, distributions are made to the partners with respect to each calendar quarter in an amount equal to 100 percent of available cash as defined in the ONEOK Partners partnership agreement (Partnership Agreement), as amended. Available cash generally will be distributed 98 percent to limited partners and 2 percent to the general partner. The 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 ONEOK Partners’ partnership agreement, as amended, the 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.
	The following table shows ONEOK Partners’ distributions paid during the periods indicated:
			Years Ended December 31,
			2014		2013		2012
			(Thousands, except per unit amounts)
	Distribution per unit		$	3.01	$	2.87	$	2.59
	General partner distributions		$	21,044	$	18,193	$	15,217
	Incentive distributions		304,999		251,664		186,130
	Distributions to general partner		326,043		269,857		201,347
	Limited partner distributions to ONEOK		279,292		266,302		235,442
	Limited partner distributions to noncontrolling interest		446,910		373,554		324,123
	Total distributions paid		$	1,052,245	$	909,713	$	760,912
	ONEOK Partners’ distributions are declared and paid within 45 days of the end of each quarter. The following table shows ONEOK Partners’ distributions declared for the periods indicated:
			Years Ended December 31,
			2014		2013		2012
			(Thousands, except per unit amounts)
	Distribution per unit		$	3.07	$	2.89	$	2.69
	General partner distributions		$	22,109	$	18,625	$	16,355
	Incentive distributions		326,022		259,466		210,095
	Distributions to general partner		348,131		278,091		226,450
	Limited partner distributions to ONEOK		284,860		268,157		249,600
	Limited partner distributions to noncontrolling interest		472,466		384,988		341,704
	Total distributions declared		$	1,105,457	$	931,236	$	817,754
	Relationship - We consolidate ONEOK Partners in our consolidated financial statements; however, we are restricted from the assets and cash flows of ONEOK Partners except for the distributions we receive. Distributions are declared quarterly by ONEOK Partners’ general partner based on the terms of the ONEOK Partners partnership agreement. See Note S for more information on ONEOK Partners’ results.
	Affiliate Transactions - Prior to the wind down of the energy services business, ONEOK Partners sold natural gas from its natural gas gathering and processing operations to our former energy services business. In addition, a portion of ONEOK Partners’ revenues from its natural gas pipelines business were from our former energy services and natural gas distribution businesses, which contracted with ONEOK Partners for natural gas transportation and storage services. ONEOK Partners also purchased natural gas from our former energy services business for its natural gas liquids and its natural gas gathering and processing operations. While these transactions were eliminated in consolidation in prior periods, they are now reflected as affiliate transactions and not eliminated in consolidation for all periods presented as these transactions have continued with either ONE Gas or other unaffiliated third parties. See Note B for additional information.
	We provide a variety of services to our affiliates, including cash management and financial services, employee benefits, legal and administrative services by our employees and management, insurance and office space leased in our headquarters building and other field locations. Where costs are incurred specifically on behalf of an affiliate, the costs are billed directly to the affiliate by us. In other situations, the costs may be allocated to the affiliates through a variety of methods, depending upon the nature of the expenses and the activities of the affiliates. Beginning in the second quarter 2014, we allocate substantially all of our general overhead costs to ONEOK Partners as a result of the separation of our former natural gas distribution business and the wind down of our former energy services business in the first quarter 2014. For the first quarter 2014 and years ended December 31, 2013 and 2012, it is not practicable to determine what these general overhead costs would be on a stand-alone basis.
	The following table shows ONEOK Partners’ transactions with us for the periods indicated:
			Years Ended December 31,
			2014		2013		2012
			(Thousands of dollars)
	Revenues		$	53,526	$	340,743	$	352,099
	Expenses
	Cost of sales and fuel		$	10,835	$	37,963	$	33,094
	Administrative and general expenses		330,541		265,448		246,050
	Total expenses		$	341,376	$	303,411	$	279,144
	Prior to the ONE Gas separation, ONEOK Partners provided natural gas sales and transportation and storage services to our former natural gas distribution business. Prior to February 1, 2014, these revenues and related costs were eliminated in consolidation. Beginning February 1, 2014, these revenues represent third-party transactions with ONE Gas and are not eliminated in consolidation, as such sales and services have continued subsequent to the separation and are expected to continue in future periods. Prior to the completion of the energy services wind down, ONEOK Partners provided natural gas and natural gas liquids sales and transportation and storage services to our energy services business. While these transactions were eliminated in consolidation in previous periods, they are now reflected as affiliate transactions and not eliminated in consolidation as these transactions have continued with third parties. See Note B for additional detail on these revenues.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES
	R.	COMMITMENTS AND CONTINGENCIES
	Commitments - Operating leases represent future minimum lease payments under noncancelable leases covering office space, pipeline equipment, and vehicles. Rental expense in 2014, 2013 and 2012 was not material. ONEOK and ONEOK Partners have no material operating leases. Firm transportation and storage contracts are fixed-price contracts that provide us with firm transportation and storage capacity. The following table sets forth ONEOK Partners’ firm transportation and storage contract payments for our continuing operations for the periods indicated:
	ONEOK		Firm
	Partners		Transportation
			and Storage
			Contracts
			(Millions of dollars)
	2015		$	33.6
	2016		32.1
	2017		30.4
	2018		29.4
	2019		28.8
	Thereafter		68.5
	Total		$	222.8
	Environmental Matters - ONEOK Partners is 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 ONEOK Partners 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 ONEOK Partners to fines, penalties and/or interruptions in our operations that could be material to its results of operations. For example, if a leak or spill of hazardous substances or petroleum products occurs from pipelines or facilities that ONEOK Partners owns, operates or otherwise uses, ONEOK Partners could be held jointly and severally liable for all resulting liabilities, including response, investigation and cleanup costs, which could affect materially its results of operations and cash flows. In addition, emissions controls and/or other regulatory or permitting mandates under the Clean Air Act and other similar federal and state laws could require unexpected capital expenditures at ONEOK Partners’ facilities. ONEOK Partners cannot assure that existing environmental statutes and regulations will not be revised or that new regulations will not be adopted or become applicable to it.
	In June 2013, the Executive Office of the President of the United States (the President) issued the President’s Climate Action Plan, which includes, among other things, plans for further regulatory actions to reduce carbon emissions from various sources. On March 28, 2014, the President released the Climate Action Plan - Strategy to Reduce Methane Emissions (Methane Strategy) that lists a number of actions the federal agencies will undertake to continue to reduce above-ground methane emissions from several industries, including the oil and natural gas sectors. The proposed measures outlined in the Methane Strategy include, without limitation, the following: collaboration with the states to encourage emission reductions; standards to minimize natural gas venting and flaring on public lands; policy recommendations for reducing emissions from energy infrastructure to increase the performance of the nation’s energy transmission, storage and distribution systems; and continued efforts by PHMSA to require pipeline operators to take steps to eliminate leaks and prevent accidental methane releases and evaluate the progress of states in replacing cast-iron pipelines. The impact of any such regulatory actions on ONEOK Partners’ facilities and operations is unknown. ONEOK Partners continues to monitor these developments and the impact they may have on its businesses. Revised or additional statutes or regulations that result in increased compliance costs or additional operating restrictions could have a significant impact on ONEOK Partners’ 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 2014, 2013 or 2012.
	The EPA’s “Tailoring Rule” regulates GHG emissions at new or modified facilities that meet certain criteria. Affected facilities are required to review best available control technology (BACT), conduct air-quality analysis, impact analysis and public reviews with respect to such emissions.  At current emission threshold levels, this rule has had a minimal impact on ONEOK Partners’ existing facilities. In addition, on June 23, 2014, the Supreme Court of the United States, in a case styled, Utility Air Regulatory Group v. EPA, 530 U.S. (2014), held that an industrial facility’s potential to emit GHG emissions alone cannot subject a facility to the permitting requirements for major stationary source provisions of the Clean Air Act. The decision invalidated the EPA’s current Triggering and Tailoring Rule for GHG Prevention of Significant Deterioration (PSD) and Title V requirements as applied to facilities considered major sources only for GHGs. However, the Court also ruled that to the extent a source pursues a capital project (new construction or expansion of existing facility), which otherwise subjects the source to major source PSD permitting for conventional criteria pollutants, the permitting authorities may impose BACT analysis and emission limits for GHGs from those sources. ONEOK Partners is in the process of evaluating the effects the decision and related pending judicial proceedings at the lower court level may have on its existing operations and the opportunities it creates for design decisions for new project applications.
	In July 2011, the EPA issued a proposed rule that would change the air emissions New Source Performance Standards, also known as NSPS, and Maximum Achievable Control Technology requirements applicable to the oil and natural gas industry, including natural gas production, processing, transmission and underground storage sectors. In April 2012, the EPA released the final rule, which includes new NSPS and air toxic standards for a variety of sources within natural gas processing plants, oil and natural gas production facilities and natural gas transmission stations. The rule also regulates emissions from the hydraulic fracturing of wells for the first time. The EPA’s final rule reflects significant changes from the proposal issued in 2011 and allows for more manageable compliance options. The NSPS final rule became effective in October 2012, but the dates for compliance vary and depend in part upon the type of affected facility and the date of construction, reconstruction or modification.
	The rule was most recently amended in December 2014. The EPA has indicated that further amendments may be issued in 2015. Based on the amendments, ONEOK Partners’ understanding of pending stakeholder responses to the NSPS rule and the proposed rule-making, ONEOK Partners does not anticipate a material impact to its 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 its 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. ONEOK Partners does not expect these expenditures will have a material impact on its results of operations, financial position or cash flows.
	Pipeline Safety - ONEOK Partners is subject to PHMSA regulations, including pipeline asset integrity-management regulations. The Pipeline Safety Improvement Act of 2002 requires pipeline companies operating high-pressure pipelines to perform integrity assessments on pipeline segments that pass through densely populated areas or near specifically designated high-consequence areas. In January 2012, The Pipeline Safety, Regulatory Certainty and Job Creation Act of 2011 was signed into law. The law increased maximum penalties for violating federal pipeline safety regulations and directs the DOT and Secretary of Transportation to conduct further review or studies on issues that may or may not be material to ONEOK Partners. These issues include but are not limited to the following:
	•	an evaluation on whether hazardous natural gas liquids and natural gas pipeline integrity-management requirements should be expanded beyond current high-consequence areas;
	•	a review of all natural gas and hazardous natural gas liquids gathering pipeline exemptions;
	•	a verification of records for pipelines in class 3 and 4 locations and high-consequence areas to confirm maximum allowable operating pressures; and
	•	a requirement to test previously untested pipelines operating above 30 percent yield strength in high-consequence areas.
	The potential capital and operating expenditures related to this legislation, the associated regulations or other new pipeline safety regulations are unknown.
	Legal Proceedings - Gas Index Pricing Litigation - As previously reported, ONEOK and its subsidiary, OESC, along with several other energy companies, are defending multiple lawsuits arising from alleged market manipulation or false reporting of natural gas prices to natural gas-index publications. On April 10, 2013, the United States Court of Appeals for the Ninth Circuit reversed the summary judgments that had been granted in favor of ONEOK, OESC and other unaffiliated defendants in the following cases: Reorganized FLI, Learjet, Arandell, Heartland and NewPage. The Ninth Circuit also reversed the summary judgment that had been granted in favor of OESC on all state law claims asserted in the Sinclair case. The Ninth Circuit remanded the cases back to the United States District Court for the District of Nevada for further proceedings. ONEOK, OESC and the other unaffiliated defendants filed a Petition for Writ of Certiorari with the United States Supreme Court on August 26, 2013, seeking review of the Ninth Circuit decision. The Ninth Circuit has ordered the cases stayed until the final disposition of the Petition for Writ of Certiorari. On July 1, 2014, the United States Supreme Court granted the Petition for Writ of Certiorari. Oral arguments were heard by the United States Supreme Court on January 12, 2015, and we expect a decision by mid-2015.
	Because of the uncertainty surrounding the Gas Index Pricing Litigation, including an insufficient description of the purported classes and other related matters, we cannot reasonably estimate a range of potential exposures at this time. However, it is reasonably possible that the ultimate resolution of these matters could result in future charges that may be material to our results of operations.
	Other Legal Proceedings -We are a party to various other litigation matters and claims that have arisen in the normal course of our operations. While the results of these various other litigation matters and claims cannot be predicted with certainty, we believe the reasonably possible losses on 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.
	ONE Gas Separation - In connection with the separation of ONE Gas, we entered into a Separation and Distribution Agreement with ONE Gas, which sets forth the agreements between us and ONE Gas regarding the principal transactions necessary to effect the separation, including cross-indemnities between us and ONE Gas. In general, we agreed to indemnify ONE Gas for any liabilities relating to our business following the separation, including ONEOK Partners and our energy services business, and ONE Gas agreed to indemnify us for liabilities relating to the natural gas distribution business. If a liability does not relate to either our remaining business or to ONE Gas, then we and ONE Gas will each be responsible for a portion of such liability.
	In addition, we entered into a Transition Services Agreement with ONE Gas. Under this agreement, ONEOK and ONE Gas agreed to provide each other with various services, including services relating to treasury and risk management, accounting, human resources and payroll management, tax compliance, telecommunications services and information technology services.

SEGMENTS

SEGMENTS	12 Months Ended
	Dec. 31, 2014
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
SEGMENTS
	S.	SEGMENTS
	Segment Descriptions - Following the separation of our natural gas distribution business into ONE Gas and wind down of our energy services business, our chief operating decision maker reviews the financial performance of each of the three businesses of ONEOK Partners on a regular basis to assess the performance of, and allocate resources to, ONEOK Partners. As a result, our reportable segments have changed to reflect the three business segments of ONEOK Partners. Prior periods presented have been recast to conform to the current presentation
	Our reportable business segments are the following:
	•	the Natural Gas Gathering and Processing segment gathers and processes natural gas;
	•	the Natural Gas Liquids segment gathers, treats, fractionates and transports NGLs and stores, markets and distributes NGL products; and
	•	the Natural Gas Pipelines segment operates regulated interstate and intrastate natural gas transmission pipelines and natural gas storage facilities.
	Other and eliminations consist of the operating and leasing operations of our headquarters building and related parking facility and other amounts needed to reconcile our reportable segments to our consolidated financial statements.
	Accounting Policies - We evaluate performance based principally on each segment’s operating income and equity earnings. The accounting policies of the segments are the same as those described in Note A. Intersegment and affiliate sales are recorded on the same basis as sales to unaffiliated customers and are discussed in further detail in Note Q. Net margin is comprised of total revenues less cost of sales and fuel. Cost of sales and fuel includes commodity purchases, fuel, storage and transportation costs. Revenues from sales and services provided by ONEOK Partners to our former natural gas distribution business, which were previously eliminated in consolidation, are now reported as third-party revenues for all periods presented.
	Customers - The primary customers of the Natural Gas Gathering and Processing segment are major and independent crude oil and natural gas production companies. The 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. The Natural Gas Pipelines segment’s customers include natural gas distribution, electric-generation, natural gas marketing, industrial and major and independent crude oil and natural gas production companies.
	For the years ended December 31, 2014, 2013 and 2012, ONEOK Partners had no single customer from which it 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:
	Year Ended December 31, 2014		Natural Gas			Natural Gas			Natural Gas		Other and			Total
			Gathering and			Liquids (a)			Pipelines (b)		Eliminations (c)
			Processing
			(Thousands of dollars)
	Sales to unaffiliated customers		$	1,478,729		$	10,329,609		$	329,801	$	3,426		$	12,141,565
	Sales to affiliated customers		41,214			—			12,312		—			53,526
	Intersegment revenues		1,447,665			215,772			8,343		(1,671,780		)	—
	Total revenues		$	2,967,608		$	10,545,381		$	350,456	$	(1,668,354	)	$	12,195,091
	Net margin		$	661,885		$	1,110,085		$	328,521	$	6,052		$	2,106,543
	Operating costs		257,658			296,402			111,037		9,790			674,887
	Depreciation and amortization		123,847			124,071			43,318		3,448			294,684
	Gain (loss) on sale of assets		219			(572		)	6,786		166			6,599
	Operating income		$	280,599		$	689,040		$	180,952	$	(7,020	)	$	1,143,571
	Equity earnings (loss) from investments		$	(56,141	)	$	27,326		$	69,818	$	—		$	41,003
	Investments in unconsolidated affiliates		$	254,818		$	490,582		$	387,253	$	—		$	1,132,653
	Total assets		$	4,727,201		$	8,082,692		$	1,823,917	$	670,750		$	15,304,560
	Noncontrolling interests in consolidated subsidiaries		$	4,251		$	163,671		$	—	$	3,245,846		$	3,413,768
	Capital expenditures		$	898,896		$	798,048		$	42,991	$	39,215		$	1,779,150
	(a) - The Natural Gas Liquids segment has regulated and nonregulated operations. The Natural Gas Liquids segment’s regulated operations had revenues of $695.9 million, of which $598.1 million was related to sales within the segment, net margin of $386.5 million and operating income of $196.1 million.
	(b) - The Natural Gas Pipelines segment has regulated and nonregulated operations. The Natural Gas Pipelines segment’s regulated operations had revenues of $290.0 million, net margin of $242.3 million and operating income of $106.5 million.
	(c) - Other and Eliminations includes assets and capital expenditures of discontinued operations of $28.0 million and $23.9 million, respectively.
	Year Ended December 31, 2013		Natural Gas			Natural Gas			Natural Gas		Other and			Total
			Gathering and			Liquids (a)			Pipelines (b)		Eliminations (c)
			Processing
			(Thousands of dollars)
	Sales to unaffiliated customers		$	665,169		$	10,644,117		$	219,244	$	2,606		$	11,531,136
	Sales to affiliated customers		238,600			—			102,143		—			340,743
	Intersegment revenues		1,147,713			133,910			4,127		(1,285,750		)	—
	Total revenues		$	2,051,482		$	10,778,027		$	325,514	$	(1,283,144	)	$	11,871,879
	Net margin		$	500,627		$	869,938		$	285,719	$	(6,618	)	$	1,649,666
	Operating costs		193,293			236,638			101,182		10,473			541,586
	Depreciation and amortization		103,962			89,240			43,541		2,600			239,343
	Gain (loss) on sale of assets		436			843			10,602		—			11,881
	Operating income		$	203,808		$	544,903		$	151,598	$	(19,691	)	$	880,618
	Equity earnings from investments		$	23,493		$	21,978		$	65,046	$	—		$	110,517
	Investments in unconsolidated affiliates		$	333,179		$	491,856		$	404,803	$	—		$	1,229,838
	Total assets		$	3,949,813		$	6,938,633		$	1,817,675	$	5,035,360		$	17,741,481
	Noncontrolling interests in consolidated subsidiaries		$	4,521		$	—		$	—	$	2,502,808		$	2,507,329
	Capital expenditures		$	774,379		$	1,128,345		$	34,699	$	319,162		$	2,256,585
	(a) - The Natural Gas Liquids segment has regulated and nonregulated operations. The Natural Gas Liquids segment’s regulated operations had revenues of $534.8 million, of which $449.9 million was related to sales within the segment, net margin of $327.4 million and operating income of $190.5 million.
	(b) - The Natural Gas Pipelines segment has regulated and nonregulated operations. The Natural Gas Pipelines segment’s regulated operations had revenues of $246.9 million, net margin of $217.6 million and operating income of $90.5 million.
	(c) - Other and Eliminations includes assets and capital expenditures of discontinued operations of $4.4 billion and $292.1 million, respectively.
	Year Ended December 31, 2012		Natural Gas			Natural Gas			Natural Gas		Other and			Total
			Gathering and			Liquids (a)			Pipelines (b)		Eliminations (c)
			Processing
			(Thousands of dollars)
	Sales to unaffiliated customers		$	436,629		$	9,176,389		$	217,034	$	1,970		$	9,832,022
	Sales to affiliated customers		253,136			—			98,963		—			352,099
	Intersegment revenues		825,948			80,274			4,388		(910,610		)	—
	Total revenues		$	1,515,713		$	9,256,663		$	320,385	$	(908,640	)	$	10,184,121
	Net margin		$	455,170		$	907,340		$	286,060	$	(4,768	)	$	1,643,802
	Operating costs		164,033			223,844			101,899		1,949			491,725
Depreciation and amortization		83,031			74,344			45,726		2,233			205,334
Gain (loss) on sale of assets		2,278			(932		)	5,390		—			6,736
Operating income		$	210,384		$	608,220		$	143,825	$	(8,950	)	$	953,479
Equity earnings from investments		$	29,103		$	20,701		$	73,220	$	—		$	123,024
Investments in unconsolidated affiliates		$	333,210		$	494,878		$	393,317	$	—		$	1,221,405
Total assets		$	3,040,198		$	5,620,420		$	1,812,711	$	5,427,644		$	15,900,973
Noncontrolling interests in consolidated subsidiaries		$	4,752		$	—		$	—	$	2,098,089		$	2,102,841
Capital expenditures		$	566,126		$	968,549		$	25,383	$	306,095		$	1,866,153
(a) - The Natural Gas Liquids segment has regulated and nonregulated operations. The Natural Gas Liquids segment’s regulated operations had revenues of $470.6 million, of which $397.7 million related to sales within the segment, net margin of $276.3 million and operating income of $162.8 million.
(b) - The Natural Gas Pipelines segment has regulated and nonregulated operations. The Natural Gas Pipelines segment’s regulated operations had revenues of $251.5 million, net margin of $220.3 million and operating income of $99.3 million.
(c) - Other and Eliminations includes assets and capital expenditures of discontinued operations of $4.5 billion and $280.3 million, respectively.

QUARTERLY_FINANCIAL_DATA_UNAUD

QUARTERLY FINANCIAL DATA (UNAUDITED)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY FINANCIAL DATA (UNAUDITED)
	T.	QUARTERLY FINANCIAL DATA (UNAUDITED)
			First		Second			Third			Fourth
	Year Ended December 31, 2014		Quarter		Quarter			Quarter			Quarter
			(Thousands of dollars except per share amounts)
	Total revenues		$	3,163,296	$	3,066,882		$	3,120,145		$	2,844,768
	Net margin		$	510,627	$	495,480		$	536,941		$	563,495
	Income from continuing operations		$	204,737	$	148,760		$	114,452		$	200,766
	Income (loss) from discontinued operations, net of tax		$	1,774	$	(8,009	)	$	(171	)	$	799
	Net income		$	206,511	$	140,751		$	114,281		$	201,565
	Net income attributable to ONEOK		$	93,515	$	61,590		$	64,458		$	94,544
	Earnings per share total
	Basic		$	0.45	$	0.29		$	0.31		$	0.45
	Diluted		$	0.45	$	0.29		$	0.31		$	0.45
			First		Second			Third			Fourth
	Year Ended December 31, 2013		Quarter		Quarter			Quarter			Quarter
			(Thousands of dollars except per share amounts)
	Total revenues		$	2,517,955	$	2,768,984		$	3,135,381		$	3,449,559
	Net margin		$	371,107	$	412,758		$	424,222		$	441,579
	Income from continuing operations		$	110,503	$	153,777		$	157,824		$	166,986
	Income (loss) from discontinued operations, net of tax		$	55,202	$	(74,282	)	$	(10,126	)	$	17,077
	Net income		$	165,705	$	79,495		$	147,698		$	184,063
	Net income attributable to ONEOK		$	112,521	$	919		$	62,356		$	90,737
	Earnings per share total
	Basic		$	0.55	$	—		$	0.3		$	0.44
	Diluted		$	0.54	$	—		$	0.3		$	0.43

SUMMARY_OF_SIGNIFICANT_ACCOUNT1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Consolidation	Consolidation - Our consolidated financial statements include the accounts of ONEOK and our subsidiaries over which we have control or are the primary beneficiary. We have recorded noncontrolling interests in consolidated subsidiaries on our Consolidated Balance Sheets to recognize the portion of ONEOK Partners that we do not own. We reflected our ownership interest in ONEOK Partners’ accumulated other comprehensive income (loss) in our consolidated accumulated other comprehensive income (loss). The remaining portion is reflected as an adjustment to noncontrolling interests in consolidated subsidiaries.
	ONEOK Partners provides natural gas sales and transportation and storage services to our former natural gas distribution business. Prior to the completion of the energy services wind down, ONEOK Partners provided natural gas sales and transportation and storage services to our former energy services business. While these transactions were eliminated in consolidation in previous periods, they are reflected now as affiliate transactions and not eliminated in consolidation for all periods presented as these transactions have continued with third parties. See Note B for additional information.
	All other significant intercompany balances and transactions have been eliminated in consolidation.
	Investments in unconsolidated affiliates are accounted for using the equity method if we have the ability to exercise significant influence over operating and financial policies of our investee. Under this method, an investment is carried at its acquisition cost and adjusted each period for contributions made, distributions received and our share of the investee’s comprehensive income. For the investments we account for under the equity method, the premium or excess cost over underlying fair value of net assets is referred to as equity method goodwill. Impairment of equity investments is recorded when the impairments are other than temporary. These amounts are recorded as investments in unconsolidated affiliates on our accompanying Consolidated Balance Sheets.  See Note P for disclosures of our unconsolidated affiliates.
	Distributions paid to us from our unconsolidated affiliates are classified as operating activities on our Consolidated Statements of Cash Flows until the cumulative distributions exceed our proportionate share of income from the unconsolidated affiliate since the date of our initial investment.  The amount of cumulative distributions paid to us that exceeds our cumulative proportionate share of income in each period represents a return of investment and is classified as an investing activity on our Consolidated Statements of Cash Flows.
Use of Estimates	Use of Estimates - The preparation of our consolidated financial statements and related disclosures in accordance with GAAP requires us to make estimates and assumptions with respect to values or conditions that cannot be known with certainty that affect the reported amount of assets and liabilities, and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements. These estimates and assumptions also affect the reported amounts of revenue and expenses during the reporting period. Items that may be estimated include, but are not limited to, the economic useful life of assets, fair value of assets, liabilities and equity method investments, obligations under employee benefit plans, provisions for uncollectible accounts receivable, unbilled revenues and cost of goods sold, expenses for services received but which no invoice has been received, provision for income taxes, including any deferred tax valuation allowances, the results of litigation and various other recorded or disclosed amounts.
	We evaluate these estimates on an ongoing basis using historical experience, consultation with experts and other methods we consider reasonable based on the particular circumstances. Nevertheless, actual results may differ significantly from the estimates. Any effects on our financial position or results of operations from revisions to these estimates are recorded in the period when the facts that give rise to the revision become known.
Fair Value Measurements	Fair Value Measurements - We define fair value as the price that would be received from the sale of an asset or the transfer of a liability in an orderly transaction between market participants at the measurement date. We use market and income approaches to determine the fair value of our assets and liabilities and consider the markets in which the transactions are executed. We measure the fair value of a group of financial assets and liabilities consistent with how a market participant would price the net risk exposure at the measurement date.
	While many of the contracts in ONEOK Partners’ portfolio are executed in liquid markets where price transparency exists, some contracts are executed in markets for which market prices may exist, but the market may be relatively inactive. This results in limited price transparency that requires management’s judgment and assumptions to estimate fair values. For certain transactions, we utilize modeling techniques using NYMEX-settled pricing data and implied forward LIBOR curves. Inputs into our fair value estimates include commodity-exchange prices, over-the-counter quotes, historical correlations of pricing data and LIBOR and other liquid money-market instrument rates. We also utilize internally developed basis curves that incorporate observable and unobservable market data. We validate our valuation inputs with third-party information and settlement prices from other sources, where available.
	In addition, as prescribed by the income approach, we compute the fair value of our derivative portfolio by discounting the projected future cash flows from our derivative assets and liabilities to present value using interest-rate yields to calculate present-value discount factors derived from LIBOR, Eurodollar futures and interest-rate swaps. We also take into consideration the potential impact on market prices of liquidating positions in an orderly manner over a reasonable period of time under current market conditions. We consider current market data in evaluating counterparties’, as well as our own, nonperformance risk, net of collateral, by using specific and sector bond yields and monitoring the credit default swap markets. Although we use our best estimates to determine the fair value of the derivative contracts we have executed, the ultimate market prices realized could differ from our estimates, and the differences could be material.
	The fair value of our forward-starting interest-rate swaps are determined using financial models that incorporate the implied forward LIBOR yield curve for the same period as the future interest swap settlements.
	Fair Value Hierarchy - At each balance sheet date, we utilize a fair value hierarchy to classify fair value amounts recognized or disclosed in our financial statements based on the observability of inputs used to estimate such fair value.  The levels of the hierarchy are described below:
	•	Level 1 - fair value measurements are based on unadjusted quoted prices for identical securities in active markets including NYMEX-settled prices. These balances are comprised predominantly of exchange-traded derivative contracts for natural gas and crude oil.
	•	Level 2 - fair value measurements are based on significant observable pricing inputs, such as NYMEX-settled prices for natural gas and crude oil and financial models that utilize implied forward LIBOR yield curves for interest-rate swaps.
	•	Level 3 - fair value measurements are based on inputs that may include one or more unobservable inputs, including internally developed basis curves that incorporate observable and unobservable market data, NGL price curves from broker quotes, market volatilities derived from the most recent NYMEX close spot prices and forward LIBOR curves, and adjustments for the credit risk of our counterparties. We corroborate the data on which our fair value estimates are based using our market knowledge of recent transactions, analysis of historical correlations and validation with independent broker quotes. These balances categorized as Level 3 are comprised of derivatives for natural gas and NGLs. We do not believe that our Level 3 fair value estimates have a material impact on our results of operations, as the majority of our derivatives are accounted for as hedges for which ineffectiveness is not material.
	Determining the appropriate classification of our fair value measurements within the fair value hierarchy requires management’s judgment regarding the degree to which market data is observable or corroborated by observable market data. We categorize derivatives for which fair value is determined using multiple inputs within a single level, based on the lowest level input that is significant to the fair value measurement in its entirety.
	See Note D for discussion of our fair value measurements.
Cash and Cash Equivalents	Cash and Cash Equivalents - Cash equivalents consist of highly liquid investments, which are readily convertible into cash and have original maturities of three months or less.
Revenue Recognition	Revenue Recognition - Our reportable segments recognize revenue when services are rendered or product is delivered. The Natural Gas Gathering and Processing segment records revenues when gas is processed in or transported through its facilities. The Natural Gas Liquids segment records revenues based upon contracted services and actual volumes exchanged or stored under service agreements in the period services are provided. Revenues for the Natural Gas Pipelines segment and a portion of the Natural Gas Liquids segment is recognized based upon contracted capacity and contracted volumes transported and stored under service agreements in the period services are provided.
	Our former natural gas distribution business’s major industrial and commercial natural gas distribution customers were invoiced at the end of each month. All natural gas distribution residential customers and some commercial customers were invoiced on a cyclical basis throughout the month, and the utilities accrued unbilled revenues at the end of each month. Revenues from our former natural gas distribution business are included in discontinued operations.
	Our revenues from sales to our former energy services business’s wholesale customers were accrued in the month of physical delivery based on contracted sales price and estimated volumes. Demand payments received for requirements contracts were recognized in the period in which the service was provided. Our fixed-price physical sales were accounted for as derivatives and were recorded at fair value. Revenues from our former energy services business are included in discontinued operations.
Accounts Receivable	Accounts Receivable - Accounts receivable represent valid claims against nonaffiliated customers for products sold or services rendered, net of allowances for doubtful accounts. We assess the creditworthiness of our counterparties on an ongoing basis and require security, including prepayments and other forms of collateral, when appropriate. Outstanding customer receivables are reviewed regularly for possible nonpayment indicators and allowances for doubtful accounts are recorded based upon management’s estimate of collectability at each balance sheet date. At December 31, 2014 and 2013, the allowance for doubtful accounts was not material.
Inventories	Inventory - The values of current natural gas and NGLs in storage are determined using the lower of weighted-average cost or market method.  Noncurrent natural gas and NGLs are classified as property and valued at cost.  Materials and supplies are valued at average cost.
Commodity Imbalances	Commodity Imbalances - Commodity imbalances represent amounts payable or receivable for NGL exchange contracts and natural gas pipeline imbalances and are valued at market prices. Under the majority of our NGL exchange agreements, we physically receive volumes of unfractionated NGLs, including the risk of loss and legal title to such volumes, from the exchange counterparty. In turn, we deliver NGL products back to the customer and charge them gathering and fractionation fees. To the extent that the volumes we receive under such agreements differ from those we deliver, we record a net exchange receivable or payable position with the counterparties. These net exchange receivables and payables are settled with movements of NGL products rather than with cash. Natural gas pipeline imbalances are settled in cash or in-kind, subject to the terms of the pipelines’ tariffs or by agreement.
Derivatives and Risk Management Activities	Derivatives and Risk Management - We and ONEOK Partners utilize derivatives to reduce our market risk exposure to commodity price and interest-rate fluctuations and to achieve more predictable cash flows.  We and ONEOK Partners record all derivative instruments at fair value, with the exception of normal purchases and normal sales transactions that are expected to result in physical delivery.  Commodity price and interest-rate volatility may have a significant impact on the fair value of derivative instruments as of a given date.
	The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and, if so, the reason for holding it.  The table below summarizes the various ways in which we account for our derivative instruments and the impact on our consolidated financial statements:
			Recognition and Measurement
	Accounting Treatment		Balance Sheet		Income Statement
	Normal purchases and	-	Fair value not recorded	-	Change in fair value not recognized in earnings
	normal sales
	Mark-to-market	-	Recorded at fair value	-	Change in fair value recognized in earnings
	Cash flow hedge	-	Recorded at fair value	-	Ineffective portion of the gain or loss on the
					derivative instrument is recognized in earnings
		-	Effective portion of the gain or loss on the	-	Effective portion of the gain or loss on the
			derivative instrument is reported initially as a		derivative instrument is reclassified out of
			component of accumulated other		accumulated other comprehensive income (loss)
			comprehensive income (loss)		into earnings when the forecasted transaction
					affects earnings
	Fair value hedge	-	Recorded at fair value	-	The gain or loss on the derivative instrument is
					recognized in earnings
		-	Change in fair value of the hedged item is	-	Change in fair value of the hedged item is
			recorded as an adjustment to book value		recognized in earnings
	To reduce our exposure to fluctuations in natural gas, NGLs and condensate prices, we and ONEOK Partners periodically enter into futures, forward sales, options or swap transactions in order to hedge anticipated purchases and sales of natural gas, NGLs and condensate.  Interest-rate swaps are used from time to time to manage interest-rate risk.  Under certain conditions, we and ONEOK Partners designate these derivative instruments as a hedge of exposure to changes in cash flow.  We and ONEOK Partners formally document all relationships between hedging instruments and hedged items, as well as risk-management objectives and strategies for undertaking various hedge transactions and methods for assessing and testing correlation and hedge ineffectiveness.  We and ONEOK Partners specifically identify the forecasted transaction that has been designated as the hedged item with a cash flow hedge.  We and ONEOK Partners 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.  ONEOK Partners also documents its normal purchases and normal sales transactions that are expected to result in physical delivery and that ONEOK Partners elects to exempt from derivative accounting treatment.
	The realized revenues and purchase costs of our and ONEOK Partners 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 Consolidated Statement of Cash Flows category as the cash flows from the related hedged items.
	Income from discontinued operations in our Consolidated Statements of Income includes revenues from financial trading margins, as well as certain physical natural gas transactions with our trading counterparties. Revenues and cost of sales and fuel from such physical transactions are reported on a net basis. See Note B for disclosures of our discontinued operations.
	See Notes D and E for more discussion of our fair value measurements and risk management and hedging activities using derivatives.
Property, Plant and Equipment	Property, Plant and Equipment - Our properties are stated at cost, including AFUDC. Generally, the cost of regulated property retired or sold, plus removal costs, less salvage, is charged to accumulated depreciation. Gains and losses from sales or transfers of nonregulated properties or an entire operating unit or system of our regulated properties are recognized in income. Maintenance and repairs are charged directly to expense.
	The interest portion of AFUDC represents the cost of borrowed funds used to finance construction activities. We capitalize interest costs during the construction or upgrade of qualifying assets. Capitalized interest is recorded as a reduction to interest expense. The equity portion of AFUDC represents the capitalization of the estimated average cost of equity used during the construction of major projects and is recorded in the cost of our regulated properties and as a credit to the allowance for equity funds used during construction.
	Our properties are depreciated using the straight-line method over their estimated useful lives. Generally, we apply composite depreciation rates to functional groups of property having similar economic circumstances. We periodically conduct depreciation studies to assess the economic lives of our assets. For our regulated assets, these depreciation studies are completed as a part of our rate proceedings or tariff filings, and the changes in economic lives, if applicable, are implemented prospectively when the new rates are billed. For our nonregulated assets, if it is determined that the estimated economic life changes, the changes are made prospectively. Changes in the estimated economic lives of our property, plant and equipment could have a material effect on our financial position or results of operations.
	Property, plant and equipment on our Consolidated Balance Sheets includes construction work in process for capital projects that have not yet been placed in service and therefore are not being depreciated. Assets are transferred out of construction work in process when they are substantially complete and ready for their intended use.
	See Note F for disclosures of our property, plant and equipment.
Impairment of Goodwill and Long-Lived Assets, including Intangible Assets	Impairment of Goodwill and Long-Lived Assets, Including Intangible Assets - We assess our goodwill and indefinite-lived intangible assets for impairment at least annually as of July 1. Our goodwill impairment analysis performed as of July 1, 2014, did not result in an impairment charge nor did our analysis reflect any reporting units at risk, and subsequent to that date, no event has occurred indicating that the implied fair value of each of our reporting units (including its inherent goodwill) is less than the carrying value of its net assets.
	There were no impairment charges resulting from our 2014 and 2013 annual impairment tests. As a result of the decline in natural gas prices and its effect on location and seasonal price differentials, we performed an interim impairment assessment of our former energy services business’s goodwill balance as of March 31, 2012.  As a result of that assessment, goodwill with a carrying amount of $10.3 million was written down to its implied fair value of zero, with a resulting impairment charge of $10.3 million recorded in 2012 earnings, which is included in income from discontinued operations. There were no impairment indicators for ONEOK Partners or our former natural gas distribution business as the cash flows generated from each of these businesses are derived from predominately fee-based, nondiscretionary services.
	As part of our impairment test, we first assess qualitative factors (including macroeconomic conditions, industry and market considerations, cost factors and overall financial performance) to determine whether it is more likely than not that the fair value of each of our reporting units is less than its carrying amount. If further testing is necessary, we perform a two-step impairment test for goodwill. In the first step, an initial assessment is made by comparing the fair value of a reporting unit with its book value, including goodwill. If the fair value is less than the book value, an impairment is indicated, and we must perform a second test to measure the amount of the impairment. In the second test, we calculate the implied fair value of the goodwill by deducting the fair value of all tangible and intangible net assets of the reporting unit from the fair value determined in step one of the assessment. If the carrying value of the goodwill exceeds the implied fair value of the goodwill, we will record an impairment charge.
	To estimate the fair value of our reporting units, we use two generally accepted valuation approaches, an income approach and a market approach, using assumptions consistent with a market participant’s perspective. Under the income approach, we use anticipated cash flows over a period of years plus a terminal value and discount these amounts to their present value using appropriate discount rates. Under the market approach, we apply EBITDA multiples to forecasted EBITDA. The multiples used are consistent with historical asset transactions. The forecasted cash flows are based on average forecasted cash flows for a reporting unit over a period of years.
	As part of our indefinite-lived intangible asset impairment test, we first assess qualitative factors similar to those considered in the goodwill impairment test to determine whether it is more likely than not that the indefinite-lived intangible asset was impaired. If further testing is necessary, we compare the estimated fair value of our indefinite-lived intangible asset with its book value. The fair value of our indefinite-lived intangible asset is estimated using the market approach. Under the market approach, we apply multiples to forecasted cash flows of the assets associated with our indefinite-lived intangible asset. The multiples used are consistent with historical asset transactions. After assessing qualitative factors, we determined that there were no impairments to our indefinite-lived intangible asset in 2014. There were also no impairment charges resulting from our 2013 and 2012 annual impairment tests.
	We assess our long-lived assets, including intangible assets with finite useful lives, for impairment whenever events or changes in circumstances indicate that an asset’s carrying amount may not be recoverable. An impairment is indicated if the carrying amount of a long-lived asset exceeds the sum of the undiscounted future cash flows expected to result from the use and eventual disposition of the asset. If an impairment is indicated, we record an impairment loss equal to the difference between the carrying value and the fair value of the long-lived asset. We determined that there were no asset impairments in 2014, 2013 or 2012.
	For the investments we account for under the equity method, the impairment test considers whether the fair value of the equity investment as a whole, not the underlying net assets, has declined and whether that decline is other than temporary. Therefore, we periodically reevaluate the amount at which we carry our equity method investments to determine whether current events or circumstances warrant adjustments to our carrying value.
	See Notes F, G and P for our long-lived assets, goodwill and intangible assets and investment in unconsolidated affiliates disclosures.
Regulation	Regulation - ONEOK Partners’ intrastate natural gas transmission pipelines and our former natural gas distribution business are subject to the rate regulation and accounting requirements of the OCC, KCC, RRC and various municipalities in Texas. ONEOK Partners’ interstate natural gas and natural gas liquids pipelines are subject to regulation by the FERC. In Kansas and Texas, natural gas storage may be regulated by the state and the FERC for certain types of services. Oklahoma Natural Gas, Kansas Gas Service, Texas Gas Service, which are all part of our former natural gas distribution business, and portions of the Natural Gas Liquids and Natural Gas Pipelines segments follow the accounting and reporting guidance for regulated operations. During the rate-making process for certain of ONEOK Partners’ assets, regulatory authorities set the framework for what we can charge customers for our services and establish the manner that our costs are accounted for, including allowing us to defer recognition of certain costs and permitting recovery of the amounts through rates over time, as opposed to expensing such costs as incurred. Certain examples of types of regulatory guidance include costs for fuel and losses, acquisition costs, contributions in aid of construction, charges for depreciation and gains or losses on disposition of assets. This allows us to stabilize rates over time rather than passing such costs on to the customer for immediate recovery. Actions by regulatory authorities could have an effect on the amount recovered from rate payers. Any difference in the amount recoverable and the amount deferred is recorded as income or expense at the time of the regulatory action. A write-off of regulatory assets and costs not recovered may be required if all or a portion of the regulated operations have rates that are no longer:
	•	established by independent, third-party regulators;
	•	designed to recover the specific entity’s costs of providing regulated services; and
	•	set at levels that will recover our costs when considering the demand and competition for our services.
	In December 2013, the KCC approved a settlement agreement for the separation of our Kansas Gas Service natural gas distribution business to ONE Gas from ONEOK. The terms of the settlement agreement provided that amounts previously recorded as a regulatory asset related to ONEOK’s acquisition of Kansas Gas Service in 1997 would no longer be recovered in rates. As a result, the carrying amount of the regulatory asset was written off, and we recorded a noncash charge to income from discontinued operations of approximately $10.2 million in the fourth quarter 2013.
	At December 31, 2014 and 2013, we recorded regulatory assets of approximately $6.1 million and $383.6 million, respectively, which are being recovered or are expected to be recovered as a result of various approved rate proceedings.  Of these amounts, the total regulatory assets related to our former natural gas distribution business were $376.8 million at December 31, 2013, which are included in assets of discontinued operations. The natural gas distribution balances included approximately $341.1 million related to our pension and postretirement benefit plans at December 31, 2013, which are discussed in Note N. Regulatory assets for our continuing operations, which are reflected in other assets in our Consolidated Balance Sheets, are being recovered as a result of approved rate proceedings over varying time periods up to 40 years.
Pension and Postretirement Employee Benefits	Pension and Postretirement Employee Benefits - We have a defined benefit retirement plan covering certain full-time employees. We sponsor welfare plans that provide postretirement medical and life insurance benefits to certain employees who retire with at least five years of service.  Our actuarial consultant calculates the expense and liability related to these plans and uses statistical and other factors that attempt to anticipate future events. These factors include assumptions about the discount rate, expected return on plan assets, rate of future compensation increases, mortality and employment length. In determining the projected benefit obligations and costs, assumptions can change from period to period and may result in material changes in the costs and liabilities we recognize. See Note N for more discussion of pension and postretirement employee benefits.
	We determine our overall expected long-term rate of return on plan assets, based on our review of historical returns and economic growth models.
	We determine our discount rates annually.  We estimate our discount rate based upon a comparison of the expected cash flows associated with our future payments under our pension and postretirement obligations to a hypothetical bond portfolio created using high-quality bonds that closely match expected cash flows.  Bond portfolios are developed by selecting a bond for each of the next 60 years based on the maturity dates of the bonds.  Bonds selected to be included in the portfolios are only those rated by Moody’s as AA- or better and exclude callable bonds, bonds with less than a minimum issue size, yield outliers and other filtering criteria to remove unsuitable bonds.
Income Taxes	Income Taxes - Deferred income taxes are provided for the difference between the financial statement and income tax basis of assets and liabilities and carryforward items based on income tax laws and rates existing at the time the temporary differences are expected to reverse.  Except for the regulated companies, the effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date of the rate change.  For regulated companies, the effect on deferred tax assets and liabilities of a change in tax rates is recorded as regulatory assets and regulatory liabilities in the period that includes the enactment date, if, as a result of an action by a regulator, it is probable that the effect of the change in tax rates will be recovered from or returned to customers through future rates.
	We utilize a more-likely-than-not recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position that is taken or expected to be taken in a tax return.  We reflect penalties and interest as part of income tax expense as they become applicable for tax provisions that do not meet the more-likely-than-not recognition threshold and measurement attribute.  During 2014, 2013 and 2012, our tax positions did not require an establishment of a material reserve.
	We utilize the “with-and-without” approach for intra-period tax allocation for purposes of allocating total tax expense (or benefit) for the year among the various financial statement components.
	We file numerous consolidated and separate income tax returns with federal tax authorities of the United States and Canada along with the tax authorities of several states.  There are no United States federal audits or statute waivers at this time. See Note O for additional discussion of income taxes.
Asset Retirement Obligations	Asset Retirement Obligations - Asset retirement obligations represent legal obligations associated with the retirement of long-lived assets that result from the acquisition, construction, development and/or normal use of the asset. Certain long-lived assets that comprise our former natural gas distribution systems and ONEOK Partners’ natural gas gathering and processing, natural gas liquids and pipeline facilities are subject to agreements or regulations that give rise to asset retirement obligations for removal or other disposition costs associated with retiring the assets in place upon the discontinued use of the assets. We recognize the fair value of a liability for an asset-retirement obligation in the period when it is incurred if a reasonable estimate of the fair value can be made. We are not able to estimate reasonably the fair value of the asset retirement obligations for portions of our former natural gas distribution and ONEOK Partners’ assets, primarily certain pipeline estimates, because the settlement dates are indeterminable given the expected continued use of the assets with proper maintenance. We expect our former natural gas distribution and ONEOK Partners’ pipeline assets, for which we are unable to estimate reasonably the fair value of the asset retirement obligation, will continue in operation as long as supply and demand for natural gas and natural gas liquids exists. Based on the widespread use of natural gas for heating and cooking activities for residential users and electric-power generation for commercial users, as well as use of natural gas liquids by the petrochemical industry, we expect supply and demand to exist for the foreseeable future.
	For our assets that we are able to make an estimate, the fair value of the liability is added to the carrying amount of the associated asset, and this additional carrying amount is depreciated over the life of the asset. The liability is accreted at the end of each period through charges to operating expense. If the obligation is settled for an amount other than the carrying amount of the liability, we will recognize a gain or loss on settlement. The depreciation and accretion expense are immaterial to our consolidated financial statements.
	In accordance with long-standing regulatory treatment, ONEOK Partners and our former natural gas distribution business collect, through rates, the estimated costs of removal on certain regulated properties through depreciation expense, with a corresponding credit to accumulated depreciation and amortization. These removal costs collected through rates include legal and nonlegal removal obligations; however, the amounts collected in excess of the asset-removal costs incurred are accounted for as a regulatory liability for financial reporting purposes. Historically, with the exception of the regulatory authority in Kansas, the regulatory authorities that have jurisdiction over our regulated operations have not required us to quantify this amount; rather, these costs are addressed prospectively in depreciation rates and are set in each general rate order. We have made an estimate of our regulatory liability using current rates since the last general rate order in each of our jurisdictions; however, for financial reporting purposes, significant uncertainty exists regarding the ultimate disposition of this regulatory liability, pending, among other issues, clarification of regulatory intent. We continue to monitor regulatory requirements, and the liability may be adjusted as more information is obtained.
Contingencies	Contingencies - Our accounting for contingencies covers a variety of business activities, including contingencies for legal and environmental exposures. We accrue these contingencies when our assessments indicate that it is probable that a liability has been incurred or an asset will not be recovered and an amount can be estimated reasonably. We expense legal fees as incurred and base our legal liability estimates on currently available facts and our estimates of the ultimate outcome or resolution. Accruals for estimated losses from environmental remediation obligations generally are recognized no later than completion of a remediation feasibility study. Recoveries of environmental remediation costs from other parties are recorded as assets when their receipt is deemed probable. Our expenditures for environmental evaluation, mitigation, remediation and compliance to date have not been significant in relation to our financial position or results of operations, and our expenditures related to environmental matters had no material effect on earnings or cash flows during 2014, 2013 and 2012. Actual results may differ from our estimates resulting in an impact, positive or negative, on earnings. See Note R for additional discussion of contingencies.
Share-Based Payments	Share-Based Payments - We expense the fair value of share-based payments net of estimated forfeitures.  We estimate forfeiture rates based on historical forfeitures under our share-based payment plans.
Earnings per Common Share	Earnings per Common Share - Basic EPS is calculated based on the daily weighted-average number of shares of common stock outstanding during the period. Diluted EPS is calculated based on the daily weighted-average number of shares of common stock outstanding during the period plus potentially dilutive components. The dilutive components are calculated based on the dilutive effect for each quarter. For fiscal-year periods, the dilutive components for each quarter are averaged to arrive at the fiscal year-to-date dilutive component.
Accounting Standards Update 2015-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In February 2015. the FASB issued ASU 2015-02, “Consolidation (Topic 810): Amendments to the Consolidation Analysis,” which eliminates the presumption that a general partner should consolidate a limited partnership. It also modifies the evaluation of whether limited partnerships are variable interest entities or voting interest entities and adds requirements that limited partnerships must meet to qualify as voting interest entities. This guidance is effective for public companies for fiscal years beginning after December 15, 2015. We will adopt this guidance in the first quarter 2016, and we are evaluating the impact on us.
Accounting Standards Update 2014-17 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In November 2014, the FASB issued ASU 2014-17, “Business Combination (Topic 805): Pushdown Accounting,” which provides an acquired entity with an option to apply pushdown accounting in its separate financial statements when a change-in-control event occurs. An acquired entity may elect the option to apply pushdown accounting in the reporting period in which the change-in-control event occurs. The standard applies to all entities and was effective on November 18, 2014. We adopted this guidance beginning in the fourth quarter 2014, and we do not expect it to materially impact us.
Accounting Standards Update 2014-15 [Domain]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In August 2014, the FASB issued ASU 2014-15, “Going Concern,” which provides guidance on determining when and how to disclose going-concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if conditions or events raise substantial doubt about the entity’s ability to continue as a going concern. The standard applies to all entities and is effective for annual periods ending after December 15, 2016, and interim periods thereafter, with early adoption permitted. We will adopt this guidance beginning in the first quarter 2016, and we do not expect it to materially impact us.
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In May 2014, the FASB issued ASU 2014-09, “Revenue from Contracts with Customers,” which outlines the principles an entity must apply to measure and recognize revenue for entities that enter into contracts to provide goods or services to their customers. The core principle is that an entity should recognize revenue at an amount that reflects the consideration to which the entity expects to be entitled in exchange for transferring goods or services to a customer. The amendment also requires more extensive disaggregated revenue disclosures in interim and annual financial statements. This update will be effective for interim and annual periods that begin on or after December 15, 2016, with either retrospective application for all periods presented or retrospective application with a cumulative effect adjustment. We will adopt this guidance beginning in the first quarter 2017, and we are evaluating the impact on us.
Accounting Standards Update 2014-08 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncements, Policy [Policy Text Block]	In April 2014, the FASB issued ASU 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity,” which alters the definition of a discontinued operation to include only asset disposals that represent a strategic shift with a major effect on an entity's operations and financial results.  The amendment also requires more extensive disclosures about a discontinued operation’s assets, liabilities, income, expenses and cash flows. This guidance will be effective for interim and annual periods for all assets that are disposed of or classified as being held for sale in fiscal years that begin on or after December 15, 2014. We will adopt this guidance beginning in the first quarter 2015, and it could impact us in the future if we dispose of any individually significant components.

ACQUISITIONS_ACQUISITIONS_Poli

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

LONGTERM_DEBT_LONGTERM_DEBT_Po

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

EMPLOYEE_BENEFIT_PLANS_EMPLOYE

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Pension and Other Postretirement Plans, Policy [Policy Text Block]	Pension and Postretirement Employee Benefits - We have a defined benefit retirement plan covering certain full-time employees. We sponsor welfare plans that provide postretirement medical and life insurance benefits to certain employees who retire with at least five years of service.  Our actuarial consultant calculates the expense and liability related to these plans and uses statistical and other factors that attempt to anticipate future events. These factors include assumptions about the discount rate, expected return on plan assets, rate of future compensation increases, mortality and employment length. In determining the projected benefit obligations and costs, assumptions can change from period to period and may result in material changes in the costs and liabilities we recognize. See Note N for more discussion of pension and postretirement employee benefits.
	We determine our overall expected long-term rate of return on plan assets, based on our review of historical returns and economic growth models.
	We determine our discount rates annually.  We estimate our discount rate based upon a comparison of the expected cash flows associated with our future payments under our pension and postretirement obligations to a hypothetical bond portfolio created using high-quality bonds that closely match expected cash flows.  Bond portfolios are developed by selecting a bond for each of the next 60 years based on the maturity dates of the bonds.  Bonds selected to be included in the portfolios are only those rated by Moody’s as AA- or better and exclude callable bonds, bonds with less than a minimum issue size, yield outliers and other filtering criteria to remove unsuitable bonds.

ONEOK_PARTNERS_ONEOK_PARTNERS_1

ONEOK PARTNERS ONEOK PARTNERS (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Incentive Distribution Policy, Managing Member or General Partner, Description [Policy Text Block]	We receive distributions from ONEOK Partners on our common and Class B units and our 2 percent general partner interest, which includes our incentive distribution rights. Under ONEOK Partners’ partnership agreement, as amended, distributions are made to the partners with respect to each calendar quarter in an amount equal to 100 percent of available cash as defined in the ONEOK Partners partnership agreement (Partnership Agreement), as amended. Available cash generally will be distributed 98 percent to limited partners and 2 percent to the general partner. The 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 ONEOK Partners’ partnership agreement, as amended, the 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.
Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block]	We account for the difference between the carrying amount of our investment in ONEOK Partners and the underlying book value arising from issuance of common units by ONEOK Partners as an equity transaction.  If ONEOK Partners issues common units at a price different than our carrying value per unit, we account for the premium or deficiency as an adjustment to paid-in capital.  As a result of ONEOK Partners’ issuance of common units, we recognized an increase to paid-in capital of approximately $156.1 million, net of taxes, in 2014 and an increase to paid-in capital of approximately $87.3 million, net of taxes, in 2013, and a decrease to paid-in capital of approximately $51.1 million, net of taxes, in 2012.

SEGMENTS_Accounting_Policies_P

SEGMENTS Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Segment Accounting Policy [Text Block]	We evaluate performance based principally on each segment’s operating income and equity earnings. The accounting policies of the segments are the same as those described in Note A. Intersegment and affiliate sales are recorded on the same basis as sales to unaffiliated customers and are discussed in further detail in Note Q. Net margin is comprised of total revenues less cost of sales and fuel. Cost of sales and fuel includes commodity purchases, fuel, storage and transportation costs. Revenues from sales and services provided by ONEOK Partners to our former natural gas distribution business, which were previously eliminated in consolidation, are now reported as third-party revenues for all periods presented.

DISCONTINUED_OPERATIONS_Tables

DISCONTINUED OPERATIONS (Tables)	12 Months Ended
	Dec. 31, 2014
Components of Net Income (Loss) [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operations	Results of Operations of Discontinued Operations - The results of operations for our former natural gas distribution business, including ONEOK Energy Marketing Company, and energy services business have been reported as discontinued operations for all periods presented. The tables below provide selected financial information reported in discontinued operations in the Consolidated Statements of Income for the periods presented:
		Year Ended
		31-Dec-14
		Natural Gas				Energy			Total
		Distribution				Services
		(Thousands of dollars)
	Revenues	$	287,249			$	353,404		$	640,653
	Cost of sales and fuel	190,893				364,648			555,541
	Net margin	96,356				(11,244		)	85,112
	Operating costs	60,847			(a)	5,051			65,898
	Depreciation and amortization	11,035				319			11,354
	Operating income (loss)	24,474				(16,614		)	7,860
	Other income (expense), net	(888		)		(7		)	(895		)
	Interest expense, net	(4,592		)		(413		)	(5,005		)
	Income tax benefit (expense)	(16,415		)		8,848			(7,567		)
	Income (loss) from discontinued operations, net	$	2,579			$	(8,186	)	$	(5,607	)
	(a) - Includes approximately $23.0 million for the year ended December 31, 2014, of costs related to the ONE Gas separation.
		Year Ended
		31-Dec-13
		Natural Gas				Energy			Total
		Distribution				Services
		(Thousands of dollars)
	Revenues	$	1,689,945			$	1,381,636		$	3,071,581
	Cost of sales and fuel	876,944				1,554,621			2,431,565
	Net margin	813,001				(172,985		)	640,016
	Operating costs	436,281			(a)	12,586			448,867
	Depreciation and amortization	144,758				276			145,034
	Operating income (loss)	231,962				(185,847		)	46,115
	Other income (expense), net	2,484				135			2,619
	Interest expense, net	(61,366		)		(2,195		)	(63,561		)
	Income tax benefit (expense)	(64,307		)		67,005			2,698
	Income (loss) from discontinued operations, net	$	108,773			$	(120,902	)	$	(12,129	)
	(a) - Includes approximately $9.4 million for the year ended December 31, 2013, of costs related to the ONE Gas separation.
		Year Ended
		31-Dec-12
		Natural Gas				Energy			Total
		Distribution				Services
		(Thousands of dollars)
	Revenues	$	1,404,248			$	1,421,171		$	2,825,419
	Cost of sales and fuel	646,220				1,470,514			2,116,734
	Net margin	758,028				(49,343		)	708,685
	Operating costs	400,247				17,414			417,661
	Depreciation and amortization	130,158				360			130,518
	Goodwill impairment	—				10,255			10,255
	Operating income (loss)	227,623				(77,372		)	150,251
	Other income (expense), net	1,439				147			1,586
	Interest expense, net	(60,794		)		(3,874		)	(64,668		)
	Income tax benefit (expense)	(63,647		)		28,743			(34,904		)
	Income (loss) from discontinued operations, net	$	104,621			$	(52,356	)	$	52,265
Carrying Value of Assets and Liabilities [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operations	Statement of Financial Position of Discontinued Operations - The following tables present the carrying value of assets and liabilities of our former natural gas distribution and energy services businesses included in assets and liabilities of discontinued operations in the Consolidated Balance Sheets for the periods presented:
		31-Dec-14
		Energy Services
		(Thousands of dollars)
	Assets
	Other current assets	$	16,717
	Other assets	20,020
	Total assets	$	36,737
	Liabilities
	Other current liabilities	$	44,901
	Other deferred credits	36,424
	Total liabilities	$	81,325
		31-Dec-13
		Natural Gas				Energy			Total
		Distribution				Services
		(Thousands of dollars)
	Assets
	Cash and cash equivalents	$	3,535			$	213		$	3,748
	Accounts receivable, net	368,214				87,315			455,529
	Natural gas and natural gas liquids in storage	166,128				62,663			228,791
	Other current assets	30,328				29,476			59,804
	Net property, plant and equipment	3,065,272				279			3,065,551
	Goodwill	157,953				—			157,953
	Other assets	402,161				385			402,546
	Total assets	$	4,193,591			$	180,331		$	4,373,922
	Liabilities
	Current maturities of long-term debt	$	6			$	—		$	6
	Accounts payable	168,785				77,287			246,072
	Other current liabilities	168,964				40,646			209,610
	Long-term debt, excluding current maturities	1,318				—			1,318
	Deferred income taxes	826,921				(35,221		)	791,700
	Other deferred credits	184,214				70,998			255,212
	Total liabilities	$	1,350,208			$	153,710		$	1,503,918

ACQUISITIONS_ACQUISITIONS_Tabl

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

FAIR_VALUE_MEASUREMENTS_Tables

FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Recurring Fair Value Measurments	Recurring Fair Value Measurements - The following tables set forth our recurring fair value measurements for the periods indicated:
		December 31, 2014
		Level 1			Level 2			Level 3			Total - Gross			Netting (a)			Total - Net (b)
		(Thousands of dollars)
	Assets
	Derivatives
	Commodity contracts
	Financial contracts	$	42,880		$	—		$	354		$	43,234		$	(25,979	)	$	17,255
	Physical contracts	—			—			9,922			9,922			—			9,922
	Interest-rate contracts	—			2,288			—			2,288			—			2,288
	Total derivative assets	42,880			2,288			10,276			55,444			(25,979		)	29,465
	Available-for-sale investment securities	1,773			—			—			1,773			—			1,773
	Total assets	$	44,653		$	2,288		$	10,276		$	57,217		$	(25,979	)	$	31,238
	Liabilities
	Derivatives
	Commodity contracts
	Financial contracts	$	(169	)	$	—		$	(968	)	$	(1,137	)	$	1,137		$	—
	Physical contracts	—			—			(23		)	(23		)	—			(23		)
	Interest-rate contracts	—			(44,843		)	—			(44,843		)	—			(44,843		)
	Total derivative liabilities	$	(169	)	$	(44,843	)	$	(991	)	$	(46,003	)	$	1,137		$	(44,866	)
	(a) - 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 ONEOK Partners. At December 31, 2014, ONEOK Partners had $24.8 million of cash held from various counterparties and posted no cash collateral.
	(b) - Included in other current assets, other assets or other current liabilities in our Consolidated Balance Sheets.
		December 31, 2013
		Level 1			Level 2			Level 3			Total - Gross			Netting (a)			Total - Net (b)
		(Thousands of dollars)
	Assets
	Derivatives
	Commodity contracts
	Financial contracts	$	—		$	3,657		$	2,812		$	6,469		$	(1,746	)	$	4,723
	Physical contracts	—			—			2,023			2,023			(946		)	1,077
	Interest-rate contracts	—			54,503			—			54,503			—			54,503
	Total derivative assets	—			58,160			4,835			62,995			(2,692		)	60,303
	Available-for-sale investment securities	1,569			—			—			1,569			—			1,569
	Total assets	$	1,569		$	58,160		$	4,835		$	64,564		$	(2,692	)	$	61,872
	Liabilities
	Derivatives
	Commodity contracts
	Financial contracts	$	—		$	(2,953	)	$	(2,154	)	$	(5,107	)	$	1,746		$	(3,361	)
	Physical contracts	—			—			(3,463		)	(3,463		)	946			(2,517		)
	Total derivative liabilities	$	—		$	(2,953	)	$	(5,617	)	$	(8,570	)	$	2,692		$	(5,878	)
	(a) - 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 ONEOK Partners. At December 31, 2013, ONEOK Partners had no cash collateral held or posted.
	(b) - Included in other current assets, other assets or other current liabilities in our Consolidated Balance Sheets.
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	The following tables set forth the reconciliation of our Level 3 fair value measurements for our continuing operations for the periods indicated:
		Years Ended December 31,
	Derivative Assets (Liabilities)	2014			2013
		(Thousands of dollars)
	Net assets (liabilities) at beginning of period	$	(782	)	$	(2,423	)
	Total realized/unrealized gains (losses):
	Included in earnings (a)	(927		)	959
	Included in other comprehensive income (loss)	7,260			682
	Purchases, issuances and settlements	3,734			—
	Net assets (liabilities) at end of period	$	9,285		$	(782	)
	Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets and liabilities still held as of the end of the period (a)	$	31		$	959
	(a) - Reported in commodity sales revenues in our Consolidated Statements of Income.

RISK_MANAGEMENT_AND_HEDGING_AC1

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair value of derivatives	Fair Values of Derivative Instruments - The following table sets forth the fair values of our derivative instruments for our continuing operations for the periods indicated:
		December 31, 2014								December 31, 2013
		Assets (a)				(Liabilities) (a)				Assets (a)				(Liabilities) (a)
		(Thousands of dollars)
	Derivatives designated as hedging instruments
	Commodity contracts
	Financial contracts	$	43,234			$	(1,137	)		$	6,469			$	(5,107	)
	Physical contracts	9,922				—				1,064				(3,463		)
	Interest-rate contracts	2,288				(44,843		)		54,503				—
	Total derivatives designated as hedging instruments	55,444				(45,980		)		62,036				(8,570		)
	Derivatives not designated as hedging instruments
	Commodity contracts
	Physical contracts	—				(23		)		959				—
	Total derivatives not designated as hedging instruments	—				(23		)		959				—
	Total derivatives	$	55,444			$	(46,003	)		$	62,995			$	(8,570	)
	(a) - Included on a net basis in other current assets, other assets or other current liabilities on our Consolidated Balance Sheets.
Notional amounts of derivative instruments	Notional Quantities for Derivative Instruments - The following table sets forth the notional quantities for derivative instruments held for our continuing operations for the periods indicated:
				December 31, 2014								December 31, 2013
		Contract		Purchased/				Sold/				Purchased/				Sold/
		Type		Payor				Receiver				Payor				Receiver
	Derivatives designated as hedging instruments:
	Cash flow hedges
	Fixed price
	-Natural gas (Bcf)	Futures and swaps		—				(41.2		)		—				(48.1		)
	-Crude oil and NGLs (MMBbl)	Futures, forwards and swaps		—				(0.5		)		—				(4.0		)
	Basis
	-Natural gas (Bcf)	Futures and swaps		—				(41.2		)		—				(48.1		)
	Interest-rate contracts (Millions of dollars)	Forward-starting		$	900			$	—			$	400			$	—
		swaps
Schedule of cash flow hedging instruments effect on comprehensive income (loss)	The following table sets forth the unrealized effect of cash flow hedges recognized in other comprehensive income (loss) for the periods indicated:
	Derivatives in Cash Flow		Years Ended December 31,
	Hedging Relationships		2014				2013				2012
			(Thousands of dollars)
	Continuing Operations
	Commodity contracts		$	32,354			$	(14,475	)		$	46,804
	Interest-rate contracts		(96,993		)		46,616				(29,471		)
	Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion) for continuing operations		(64,639		)		32,141				17,333
	Discontinued Operations
	Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion) for discontinued operations - commodity contracts		(3,697		)		(958		)		16,094
	Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion)		$	(68,336	)		$	31,183			$	33,427
Schedule of cash flow hedging instruments effect on income	The following tables set forth the effect of cash flow hedges on our Consolidated Statements of Income for the periods indicated:
			Location of Gain (Loss) Reclassified from
	Derivatives in Cash Flow		Accumulated Other Comprehensive Income		Years Ended December 31,
	Hedging Relationships		(Loss) into Net Income (Effective Portion)		2014				2013				2012
					(Thousands of dollars)
	Continuing Operations
	Commodity contracts		Commodity sales revenues		$	(21,052	)		$	1,689			$	61,526
	Interest-rate contracts		Interest expense		(21,966		)		(14,560		)		(7,155		)
	Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income from continuing operations on derivatives (effective portion)				(43,018		)		(12,871		)		54,371
	Discontinued Operations
	Commodity contracts		Income (loss) from discontinued operations -		(12,803		)		17,360				79,336
			Commodity sales revenues
	Commodity contracts		Income (loss) from discontinued operations -		—				(14,320		)		(73,881		)
			Cost of sales and fuel
	Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income from discontinued operations on derivatives (effective portion)				(12,803		)		3,040				5,455
	Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion)				$	(55,821	)		$	(9,831	)		$	59,826

PROPERTY_PLANT_AND_EQUIPMENT_T

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Components of Property, Plant and Equipment	The following table sets forth our property, plant and equipment for our continuing operations by property type, for the periods indicated:
		Estimated Useful	December 31,			December 31,
		Lives (Years)	2014			2013
			(Thousands of dollars)
	Nonregulated
	Gathering pipelines and related equipment	5 to 40	$	2,449,343		$	2,173,271
	Processing and fractionation and related equipment	3 to 40	2,880,572			2,295,983
	Storage and related equipment	5 to 54	478,276			362,704
	Transmission pipelines and related equipment	5 to 54	518,585			302,718
	General plant and other	2 to 60	364,976			314,919
	Construction work in process	—	1,236,138			1,085,185
	Regulated
	Storage and related equipment	5 to 54	115,799			135,922
	Natural gas transmission pipelines and related equipment	5 to 77	1,478,035			1,420,517
	Natural gas liquids transmission pipelines and related equipment	5 to 80	3,822,799			2,049,461
	General plant and other	2 to 53	63,424			53,315
	Construction work in process	—	194,700			776,261
	Property, plant and equipment		13,602,647			10,970,256
	Accumulated depreciation and amortization - nonregulated		(1,221,387		)	(1,090,268		)
	Accumulated depreciation and amortization - regulated		(718,823		)	(648,034		)
	Net property, plant and equipment		$	11,662,437		$	9,231,954
Average Depreciation Rates for Regulated Property	The average depreciation rates for our regulated property are set forth, by segment, in the following table for the periods indicated:
		Years Ended December 31,
		2014	2013		2012
	Natural Gas Liquids	2.00%	2.00%		1.90%
	Natural Gas Pipelines	2.10%	2.20%		2.20%

GOODWILL_AND_INTANGIBLE_ASSETS1

GOODWILL AND INTANGIBLE ASSETS (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill by Segment	Goodwill - The following table sets forth our goodwill by segment for the periods indicated:
		December 31,				December 31,
		2014				2013
		(Thousands of dollars)
	Natural Gas Gathering and Processing	$	122,291			$	122,291
	Natural Gas Liquids	268,544				268,544
	Natural Gas Pipelines	134,700				134,700
	Total goodwill	$	525,535			$	525,535
Gross Carrying Amount and Accumulated Amortization of Intangible Assets	Intangible Assets - The following table sets forth the gross carrying amount and accumulated amortization of intangible assets for our continuing operations for the periods indicated:
			December 31,				December 31,
			2014				2013
			(Thousands of dollars)
	Gross intangible assets		$	567,215			$	565,215
	Accumulated amortization		(78,010		)		(66,188		)
	Net intangible assets		$	489,205			$	499,027

LONGTERM_DEBT_Tables

LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2014
Long-term Debt, Unclassified [Abstract]
Long-Term Debt	The following table sets forth our long-term debt for the periods indicated:
		December 31,			December 31,
		2014			2013
		(Thousands of dollars)
	ONEOK
	$400,000 at 5.2% due 2015	$	—		$	400,000
	$700,000 at 4.25% due 2022	547,397			700,000
	$100,000 at 6.5% due 2028	87,619			87,649
	$100,000 at 6.875% due 2028	100,000			100,000
	$400,000 at 6.0% due 2035	400,000			400,000
	Total ONEOK senior notes payable	1,135,016			1,687,649
	ONEOK Partners
	$650,000 at 3.25% due 2016	650,000			650,000
	$450,000 at 6.15% due 2016	450,000			450,000
	$400,000 at 2.0% due 2017	400,000			400,000
	$425,000 at 3.2% due 2018	425,000			425,000
	$500,000 at 8.625% due 2019	500,000			500,000
	$900,000 at 3.375 % due 2022	900,000			900,000
	$425,000 at 5.0 % due 2023	425,000			425,000
	$600,000 at 6.65% due 2036	600,000			600,000
	$600,000 at 6.85% due 2037	600,000			600,000
	$650,000 at 6.125% due 2041	650,000			650,000
	$400,000 at 6.2% due 2043	400,000			400,000
	Guardian Pipeline
	Average 7.88%, due 2022	59,557			67,208
	Total ONEOK Partners senior notes payable	6,059,557			6,067,208
	Total long-term notes payable	7,194,573			7,754,857
	Unamortized portion of terminated swaps	23,622			25,340
	Unamortized debt discount	(14,616		)	(15,890		)
	Current maturities	(10,650		)	(10,650		)
	Long-term debt	$	7,192,929		$	7,753,657
Aggregate maturities of long-term debt outstanding	The aggregate maturities of long-term debt outstanding for the years 2015 through 2019 are shown below:
		ONEOK			ONEOK			Guardian		Total
					Partners			Pipeline
		(Millions of dollars)
	2015	$	3		$	—		$	7.7	$	10.7
	2016	$	3		$	1,100.00		$	7.7	$	1,110.70
	2017	$	3		$	400		$	7.7	$	410.7
	2018	$	3		$	425		$	7.7	$	435.7
	2019	$	3		$	500		$	7.7	$	510.7

EQUITY_Tables

EQUITY (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Quarterly dividends per share paid on common stock	Dividends - Dividends paid totaled $443.8 million, $304.7 million and $262.0 million for 2014, 2013 and 2012, respectively. The following table sets forth the quarterly dividends per share declared and paid on our common stock for the periods indicated:
		Years Ended December 31,
		2014		2013		2012
	First Quarter	$	0.4	$	0.36	$	0.305
	Second Quarter	$	0.56	$	0.36	$	0.305
	Third Quarter	$	0.575	$	0.38	$	0.33
	Fourth Quarter	$	0.59	$	0.38	$	0.33
	Total	$	2.125	$	1.48	$	1.27

ACCUMULATED_OTHER_COMPREHENSIV1

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	12 Months Ended
	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated other comprehensive income (loss)	The following table sets forth the balance in accumulated other comprehensive income (loss) for the periods indicated:
		Unrealized Gains				Unrealized				Pension and			Accumulated
		(Losses) on Energy				Holding Gains				Postretirement			Other
		Marketing and				(Losses)				Benefit Plan			Comprehensive
		Risk-Management				on Investment				Obligations (a) (b)			Income (Loss) (a)
		Assets/Liabilities (a)				Securities (a)
		(Thousands of dollars)
	1-Jan-13	$	(55,030	)		$	1,034			$	(162,802	)	$	(216,798	)
	Other comprehensive income (loss) before	8,842				(177		)		37,144			45,809
	reclassifications
	Amounts reclassified from accumulated other	3,020				—				45,982			49,002
	comprehensive income (loss)
	Other comprehensive income	11,862				(177		)		83,126			94,811
	(loss) attributable to ONEOK
	31-Dec-13	(43,168		)		857				(79,676		)	(121,987		)
	Other comprehensive income (loss) before	(16,225		)		98				(33,987		)	(50,114		)
	reclassifications
	Amounts reclassified from accumulated other	22,044				—				10,315			32,359
	comprehensive income (loss)
	Other comprehensive income	5,819				98				(23,672		)	(17,755		)
	(loss) attributable to ONEOK
	Transfer to ONE Gas	—				—				3,389			3,389
	31-Dec-14	$	(37,349	)		$	955			$	(99,959	)	$	(136,353	)
	(a) All amounts are presented net of tax.
	(b) Includes amounts related to supplemental executive retirement plan.
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]	The following table sets forth the effect of reclassifications from accumulated other comprehensive income (loss) on our Consolidated Statements of Income for the periods indicated:
	Details about Accumulated Other		Years Ended December 31,								Affected Line Item
	Comprehensive Income (Loss) Components										in the Consolidated
			2014				2013				Statements of Income
			(Thousands of dollars)
	Unrealized (gains) losses on energy marketing and
	risk-management assets/liabilities
	Commodity contracts		$	21,052			$	(1,689	)		Commodity sales revenues
	Interest-rate contracts		21,966				14,560				Interest expense
			43,018				12,871				Income before income taxes
			(8,977		)		(3,081		)		Income tax expense
			34,041				9,790				Income from continuing operations
			7,682				(1,864		)		Income (loss) from discontinued
											operations
			41,723				7,926				Net income
	Noncontrolling interest		19,679				4,906				Less: Net income attributable to
											noncontrolling interest
			$	22,044			$	3,020			Net income attributable to ONEOK
	Pension and postretirement benefit plan obligations (a)
	Amortization of net loss		$	15,914			$	21,407
	Amortization of unrecognized prior service cost		(1,469		)		(1,560		)
	Amortization of unrecognized net asset at adoption		—				49
			14,445				19,896				Income before income taxes
			(5,778		)		(7,958		)		Income tax expense
			8,667				11,938				Income from continuing operations
			1,648				34,044				Income from discontinued operations
			$	10,315			$	45,982			Net income attributable to ONEOK
	Total reclassifications for the period attributable to ONEOK		$	32,359			$	49,002			Net income attributable to ONEOK
	(a) These components of accumulated other comprehensive income (loss) are included in the computation of net periodic benefit cost. See Note N for additional detail of our net periodic benefit cost.

EARNINGS_PER_SHARE_Tables

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share	The following tables set forth the computation of basic and diluted EPS from continuing operations for the periods indicated:
		Year Ended December 31, 2014
		Income		Shares	Per Share
					Amount
		(Thousands, except per share amounts)
	Basic EPS from continuing operations
	Income from continuing operations attributable to ONEOK available for	$	319,714	209,391	$	1.53
	common stock
	Diluted EPS from continuing operations
	Effect of options and other dilutive securities	—		1,036
	Income from continuing operations attributable to ONEOK available for	$	319,714	210,427	$	1.52
	common stock and common stock equivalents
		Year Ended December 31, 2013
		Income		Shares	Per Share
					Amount
		(Thousands, except per share amounts)
	Basic EPS from continuing operations
	Income from continuing operations attributable to ONEOK available for	$	278,662	206,044	$	1.35
	common stock
	Diluted EPS from continuing operations
	Effect of options and other dilutive securities	—		3,651
	Income from continuing operations attributable to ONEOK available for	$	278,662	209,695	$	1.33
	common stock and common stock equivalents
		Year Ended December 31, 2012
		Income		Shares	Per Share
					Amount
		(Thousands, except per share amounts)
	Basic EPS from continuing operations
	Income from continuing operations attributable to ONEOK available for	$	294,837	206,140	$	1.43
	common stock
	Diluted EPS from continuing operations
	Effect of options and other dilutive securities	—		4,570
	Income from continuing operations attributable to ONEOK available for	$	294,837	210,710	$	1.4
	common stock and common stock equivalents

SHAREBASED_PAYMENTS_Tables

SHARE-BASED PAYMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Restricted Stock Unit and Performance Unit Activity	The following tables set forth activity and various statistics for our restricted stock unit awards:
		Number of			Weighted
		Shares			Average Price
	Nonvested December 31, 2013	776,596			$	35.27
	Granted	145,342			$	58.23
	Released to participants	(366,302	)		$	29.07
	Forfeited	(28,822	)		$	43.96
	Awards surrendered as a result of the separation	(124,263	)		$	42.9
	Awards granted in conversion as a result of the separation	45,381			$	—
	Nonvested December 31, 2014	447,932			$	41.54
		2014				2013		2012
	Weighted-average grant date fair value (per share)	$	58.23			$	47.46	$	36.65
	Fair value of shares granted (thousands of dollars)	$	8,463			$	7,940	$	11,030
	Restricted stock units held by an employee who separated from ONEOK and became an employee of ONE Gas were surrendered as a result of the separation. The number of restricted stock units held by employees who remained with ONEOK following the separation was adjusted by issuing additional units to preserve the intrinsic value of the units immediately prior to the separation.
	Performance-Unit Activity
	As of December 31, 2014, we had $13.6 million of total unrecognized compensation cost related to the nonvested performance-unit awards, which is expected to be recognized over a weighted-average period of 1.7 years.  The following tables set forth activity and various statistics related to the performance-unit awards and the assumptions used in the valuations of the 2014, 2013 and 2012 grants at the grant date:
		Number of			Weighted
		Units			Average Price
	Nonvested December 31, 2013	1,652,145			$	41.1
	Granted	186,436			$	64.75
	Released to participants	(743,897	)		$	34.68
	Forfeited	(53,927	)		$	48.99
	Awards surrendered as a result of the separation	(265,750	)		$	47.62
	Awards granted in conversion as a result of the separation	97,723			$	—
	Nonvested December 31, 2014	872,730			$	44.55
		2014		2013		2012
	Volatility (a)	25.48%		22.27%		27.00%
	Dividend Yield	2.63%		3.04%		2.86%
	Risk-free Interest Rate	0.69%		0.42%		0.38%
	(a) - Volatility was based on historical volatility over three years using daily stock price observations.
		2014				2013		2012
	Weighted-average grant date fair value (per share)	$	64.75			$	52.34	$	42.39
	Fair value of shares granted (thousands of dollars)	$	12,071			$	19,742	$	25,466

EMPLOYEE_BENEFIT_PLANS_Tables

EMPLOYEE BENEFIT PLANS (Tables)	12 Months Ended
	Dec. 31, 2014
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Pension and postretirement benefit plans obligations and fair value of plan assets	Obligations and Funded Status - The following tables set forth our pension and postretirement benefit plans benefit obligations and fair value of plan assets for our continuing operations for the periods indicated:
		Pension Benefits						Postretirement Benefits
		December 31,						December 31,
		2014			2013			2014			2013
	Change in Benefit Obligation	(Thousands of dollars)
	Benefit obligation, beginning of period	$	361,578		$	383,979		$	50,232		$	56,843
	Service cost	7,238			6,127			710			458
	Interest cost	18,324			15,626			2,433			1,164
	Plan participants’ contributions	—			—			1,537			730
	Actuarial loss (gain)	42,891			(32,120		)	6,822			(5,833		)
	Benefits paid	(12,101		)	(12,034		)	(4,815		)	(3,130		)
	Other adjustments	(3,749		)	—			(256		)	—
	Benefit obligation, end of period	414,181			361,578			56,663			50,232
	Change in Plan Assets
	Fair value of plan assets, beginning of period	274,936			243,525			28,626			24,147
	Actual return on plan assets	17,619			43,445			1,765			4,481
	Employer contributions	—			—			2,000			147
	Plan participants’ contributions	—			—			1,233			—
	Benefits paid	(12,101		)	(12,034		)	(3,968		)	(149		)
	Other adjustments	(2,886		)	—			(227		)	—
	Fair value of assets, end of period	277,568			274,936			29,429			28,626
	Balance at December 31	$	(136,613	)	$	(86,642	)	$	(27,234	)	$	(21,606	)
	Current liabilities	$	(4,634	)	$	(4,645	)	$	—		$	—
	Noncurrent liabilities	(131,979		)	(81,997		)	(27,234		)	(21,606		)
	Balance at December 31	$	(136,613	)	$	(86,642	)	$	(27,234	)	$	(21,606	)
Components of net periodic benefit cost for pension and postretirement benefit plans	Components of Net Periodic Benefit Cost - The following tables set forth the components of net periodic benefit cost for our pension and postretirement benefit plans for our continuing operations for the periods indicated:
		Pension Benefits
		Years Ended December 31,
		2014			2013			2012
		(Thousands of dollars)
	Components of net periodic benefit cost
	Service cost	$	7,238		$	6,127		$	5,633
	Interest cost	18,324			15,626			17,205
	Expected return on assets	(19,526		)	(19,874		)	(20,595		)
	Amortization of prior service cost	193			239			252
	Amortization of net loss	15,078			19,016			14,403
	Net periodic benefit cost	$	21,307		$	21,134		$	16,898
		Postretirement Benefits
		Years Ended December 31,
		2014			2013			2012
		(Thousands of dollars)
	Components of net periodic benefit cost
	Service cost	$	710		$	458		$	414
	Interest cost	2,433			1,164			1,158
	Expected return on assets	(2,163		)	(1,218		)	(891		)
	Amortization of unrecognized net asset at adoption	—			49			169
	Amortization of prior service cost	(1,662		)	(1,799		)	(2,493		)
	Amortization of net loss	836			2,391			2,975
	Net periodic benefit cost	$	154		$	1,045		$	1,332
Amounts recognized in other comprehensive income (loss)	Other Comprehensive Income (Loss) - The following tables set forth the amounts recognized in other comprehensive income (loss) related to our pension benefits and postretirement benefits for our continuing operations for the periods indicated:
		Pension Benefits
		Years Ended December 31,
		2014			2013			2012
		(Thousands of dollars)
	Net gain (loss) arising during the period	$	(49,293	)	$	51,874		$	(29,625	)
	Amortization of prior service credit	193			239			252
	Amortization of net loss	15,078			19,016			14,403
	Deferred income taxes	13,609			(28,452		)	5,988
	Total recognized in other comprehensive income (loss)	$	(20,413	)	$	42,677		$	(8,982	)
		Postretirement Benefits
		Years Ended December 31,
		2014			2013			2012
		(Thousands of dollars)
	Net gain (loss) arising during the period	$	(7,220	)	$	9,096		$	(2,423	)
	Amortization of transition obligation	—			49			169
	Amortization of prior service cost	(1,662		)	(1,799		)	(2,493		)
	Amortization of net loss	836			2,391			2,975
	Deferred income taxes	3,218			(3,895		)	709
	Total recognized in other comprehensive income (loss)	$	(4,828	)	$	5,842		$	(1,063	)
Amounts in accumulated other comprehensive income (loss)	The table below sets forth the amounts in accumulated other comprehensive income (loss) that had not yet been recognized as components of net periodic benefit expense for our continuing operations for the periods indicated:
		Pension Benefits						Postretirement Benefits
		December 31,						December 31,
		2014			2013			2014			2013
		(Thousands of dollars)
	Prior service credit (cost)	$	(94	)	$	(287	)	$	6,873		$	8,535
	Accumulated loss	(156,985		)	(122,770		)	(16,396		)	(10,012		)
	Accumulated other comprehensive loss	(157,079		)	(123,057		)	(9,523		)	(1,477		)
	Deferred income taxes	62,832			49,223			3,811			591
	Accumulated other comprehensive loss, net of tax	$	(94,247	)	$	(73,834	)	$	(5,712	)	$	(886	)
Amounts in either accumulated comprehensive income (loss) or regulatory assets expected to be recognized as components of net periodic benefit expense	The following table sets forth the amounts recognized in accumulated comprehensive income (loss) expected to be recognized as components of net periodic benefit expense for our continuing operations in the next fiscal year.
		Pension			Postretirement
		Benefits			Benefits
	Amounts to be recognized in 2015	(Thousands of dollars)
	Prior service (credit) cost	$	94		$	(1,662	)
	Net loss	$	15,981		$	1,743
Weighted-average assumptions used to determine benefit obligations and net periodic benefit costs	Actuarial Assumptions - The following table sets forth the weighted-average assumptions used to determine benefit obligations for pension and postretirement benefits for the periods indicated:
		Pension Benefits			Postretirement Benefits
		December 31,			December 31,
		2014		2013	2014		2013
	Discount rate	4.50%		5.25%	4.25%		5.00%
	Compensation increase rate	3.15%		3.20%	3.15%		3.20%
	The following table sets forth the weighted-average assumptions used to determine net periodic benefit costs for the periods indicated:
		Years Ended December 31,
		2014		2013	2012
	Discount rate - pension plans	5.25%		4.25%	5.00%
	Discount rate - postretirement plans	5.00%		4.00%	5.00%
	Expected long-term return on plan assets	7.75%		8.25%	8.25%
	Compensation increase rate	3.20%		3.50%	3.80%
Assumed health care cost trend rates	Health Care Cost Trend Rates - The following table sets forth the assumed health care cost-trend rates for the periods indicated:
		2014		2013
	Health care cost-trend rate assumed for next year	4.0% - 7.75%		4.0% - 8.25%
	Rate to which the cost-trend rate is assumed to decline	4.0% - 5.0%		5.00%
	(the ultimate trend rate)
	Year that the rate reaches the ultimate trend rate	2022		2022
Effects of a one percentage point change in assumed health care costs trend rates	Assumed health care cost-trend rates have an impact on the amounts reported for our health care plans.  A one percentage point change in assumed health care cost-trend rates would have the following effects on our continuing operations:
		One Percentage			One Percentage
		Point Increase			Point Decrease
		(Thousands of dollars)
	Effect on total of service and interest cost	$	74		$	(67	)
	Effect on postretirement benefit obligation	$	1,131		$	(1,025	)
Schedule of allocation of plan assets	Plan Assets - Our investment strategy is to invest plan assets in accordance with sound investment practices that emphasize long-term fundamentals.  The goal of this strategy is to maximize investment returns while managing risk in order to meet the plan’s current and projected financial obligations. The investment policy follows a glide path approach toward liability-driven investing that shifts a higher portfolio weighting to fixed income as the plan's funded status increases.  The purpose of liability-driven investing is to structure the asset portfolio to more closely resemble the pension liability and thereby more effectively hedge against changes in the liability. The plan’s current investments include a diverse blend of various domestic and international equities, investments in various classes of debt securities, insurance contracts and venture capital.  The target allocation for the assets of our pension plan as of December 31, 2014, is as follows:
	U.S. large-cap equities	37	%
	Aggregate bonds	24	%
	Developed foreign large-cap equities	10	%
	Alternative investments	8	%
	Mid-cap equities	6	%
	Emerging markets equities	5	%
	Small-cap equities	4	%
	High-yield bonds	3	%
	Developed foreign bonds	2	%
	Emerging market bonds	1	%
	Total	100	%
	As part of our risk management for the plans, minimums and maximums have been set for each of the asset classes listed above. All investment managers for the plan are subject to certain restrictions on the securities they purchase and, with the exception of indexing purposes, are prohibited from owning our stock.
	The following tables set forth our pension benefits and postretirement benefits plan assets by fair value category for our continuing operations as of the measurement date:
		Pension Benefits
		31-Dec-14
	Asset Category	Level 1			Level 2			Level 3			Total
		(Thousands of dollars)
	Investments:
	Equity securities (a)	$	160,421		$	15,315		$	—		$	175,736
	Government obligations	—			21,044			—			21,044
	Corporate obligations (b)	—			55,948			—			55,948
	Cash and money market funds (c)	4,610			—			—			4,610
	Other investments (d)	—			—			20,230			20,230
	Total assets	$	165,031		$	92,307		$	20,230		$	277,568
	(a) - This category represents securities of the respective market sector from diverse industries.
	(b) - This category represents bonds from diverse industries.
	(c) - This category is primarily money market funds.
	(d) - This category represents alternative investments.
		Pension Benefits
		31-Dec-13
	Asset Category	Level 1			Level 2			Level 3			Total
		(Thousands of dollars)
	Investments:
	Equity securities (a)	$	178,329		$	15,809		$	—		$	194,138
	Government obligations	—			29,160			—			29,160
	Corporate obligations (b)	—			25,005			—			25,005
	Cash and money market funds (c)	7,258			—			—			7,258
	Other investments (d)	—			—			19,375			19,375
	Total assets	$	185,587		$	69,974		$	19,375		$	274,936
	(a) - This category represents securities of the respective market sector from diverse industries.
	(b) - This category represents bonds from diverse industries.
	(c) - This category is primarily money market funds.
	(d) - This category represents alternative investments.
		Postretirement Benefits
		31-Dec-14
	Asset Category	Level 1			Level 2			Level 3			Total
		(Thousands of dollars)
	Investments:
	Equity securities (a)	$	1,599		$	—		$	—		$	1,599
	Cash and money market funds	1,644			—			—			1,644
	Insurance and group annuity contracts	—			26,186			—			26,186
	Total assets	$	3,243		$	26,186		$	—		$	29,429
	(a) - This category represents securities of the respective market sector from diverse industries.
		Postretirement Benefits
		31-Dec-13
	Asset Category	Level 1			Level 2			Level 3			Total
		(Thousands of dollars)
	Investments:
	Equity securities (a)	$	1,464		$	—		$	—		$	1,464
	Cash and money market funds (b)	1,300			—			—			1,300
	Insurance and group annuity contracts	—			25,862			—			25,862
	Total assets	$	2,764		$	25,862		$	—		$	28,626
	(a) - This category represents securities of the respective market sector from diverse industries.
(b) - This category represents money market funds.
Reconciliation of Level 3 fair value measurements of pension plan	The following tables set forth the reconciliation of Level 3 fair value measurements of our pension plan for our continuing operations for the periods indicated:
		Pension Benefits
		Years Ended December 31,
		2014			2013
		(Thousands of dollars)
	Fair value of plan assets at beginning of period	$	19,375		$	17,842
	Net realized and unrealized gains (losses)	855			1,533
	Fair value of plan assets at end of period	$	20,230		$	19,375
Pension benefits and postretirement benefit payments expected to be paid	The following table sets forth the pension benefits and postretirement benefits payments expected to be paid in 2015-2024 for our continuing operations:
		Pension			Postretirement
		Benefits			Benefits
	Benefits to be paid in:	(Thousands of dollars)
	2015	$	13,928		$	2,865
	2016	$	14,914		$	3,011
	2017	$	15,887		$	3,260
	2018	$	16,979		$	3,442
	2019	$	18,025		$	3,601
	2020 through 2024	$	104,652		$	19,023

INCOME_TAXES_Tables

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Provisions for Income Taxes	The following table sets forth our provisions for income taxes for the periods indicated:
		Years Ended December 31,
		2014			2013			2012
	Current income taxes	(Thousands of dollars)
	Federal	$	10,180		$	(9,531	)	$	41,246
	State	3,311			1,812			1,798
	Total current income taxes from continuing operations	13,491			(7,719		)	43,044
	Deferred income taxes
	Federal	152,352			156,818			134,208
	State	(14,685		)	16,981			3,506
	Total deferred income taxes from continuing operations	137,667			173,799			137,714
	Total provision for income taxes from continuing operations	151,158			166,080			180,758
	Discontinued operations	7,567			(2,698		)	43,186
	Total provision for income taxes	$	158,725		$	163,382		$	223,944
Reconciliation of Income Tax Provision	The following table is a reconciliation of our income tax provision from continuing operations for the periods indicated:
		Years Ended December 31,
		2014			2013			2012
		(Thousands of dollars)
	Income from continuing operations before income taxes	$	819,873		$	755,170		$	858,506
	Less: Net income attributable to noncontrolling interest	349,001			310,428			382,911
	Income from continuing operations attributable to ONEOK before	470,872			444,742			475,595
	income taxes
	Federal statutory income tax rate	35		%	35		%	35		%
	Provision for federal income taxes	164,805			155,660			166,458
	State income taxes, net of federal tax benefit	14,278			12,102			7,908
	State deferred tax rate change, net of valuation allowance	(25,653		)	—			—
	Other, net	(2,272		)	(1,682		)	6,392
	Income tax provision from continuing operations	$	151,158		$	166,080		$	180,758
Schedule of Deferred Tax Assets and Liabilities	The following table sets forth the tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and liabilities for our continuing operations for the periods indicated:
		December 31,			December 31,
		2014			2013
	Deferred tax assets	(Thousands of dollars)
	Employee benefits and other accrued liabilities	$	81,905		$	78,136
	Federal net operating loss	80,851			12,484
	State net operating loss and benefits	38,429			38,322
	Derivative instruments	22,511			22,872
	Other	13,133			7,582
	Total deferred tax assets	236,829			159,396
	Valuation allowance for state tax credits
	Carryforward expected to expire prior to utilization	(8,807		)	—
	Net deferred tax assets	228,022			159,396
	Deferred tax liabilities
	Excess of tax over book depreciation	89,379			60,725
	Investment in partnerships	1,466,456			1,217,605
	Regulatory assets	1,961			2,625
	Total deferred tax liabilities	1,557,796			1,280,955
	Net deferred tax liabilities before discontinued operations	1,329,774			1,121,559
	Discontinued operations	(35,559		)	775,862
	Net deferred tax liabilities	$	1,294,215		$	1,897,421

UNCONSOLIDATED_AFFILIATES_Tabl

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

ONEOK_PARTNERS_Tables

ONEOK PARTNERS (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill [Line Items]
Goodwill by Segment	Goodwill - The following table sets forth our goodwill by segment for the periods indicated:
		December 31,			December 31,
		2014			2013
		(Thousands of dollars)
	Natural Gas Gathering and Processing	$	122,291		$	122,291
	Natural Gas Liquids	268,544			268,544
	Natural Gas Pipelines	134,700			134,700
	Total goodwill	$	525,535		$	525,535
Ownership interest in ONEOK Partners	Ownership Interest in ONEOK Partners - Our ownership interest in ONEOK Partners is shown in the table below as of December 31, 2014:
	General partner interest		2	%
	Limited partner interest (a)		35.8	%
	Total ownership interest		37.8	%
	(a) - Represents 19.8 million common units and approximately 73.0 million Class B units, which are convertible, at our option, into common units.
ONEOK Partners' Distributions Paid	The following table shows ONEOK Partners’ distributions paid during the periods indicated:
			Years Ended December 31,
			2014			2013		2012
			(Thousands, except per unit amounts)
	Distribution per unit		$	3.01		$	2.87	$	2.59
	General partner distributions		$	21,044		$	18,193	$	15,217
	Incentive distributions		304,999			251,664		186,130
	Distributions to general partner		326,043			269,857		201,347
	Limited partner distributions to ONEOK		279,292			266,302		235,442
	Limited partner distributions to noncontrolling interest		446,910			373,554		324,123
	Total distributions paid		$	1,052,245		$	909,713	$	760,912
ONEOK Partners' Distributions Declared	The following table shows ONEOK Partners’ distributions declared for the periods indicated:
			Years Ended December 31,
			2014			2013		2012
			(Thousands, except per unit amounts)
	Distribution per unit		$	3.07		$	2.89	$	2.69
	General partner distributions		$	22,109		$	18,625	$	16,355
	Incentive distributions		326,022			259,466		210,095
	Distributions to general partner		348,131			278,091		226,450
	Limited partner distributions to ONEOK		284,860			268,157		249,600
	Limited partner distributions to noncontrolling interest		472,466			384,988		341,704
	Total distributions declared		$	1,105,457		$	931,236	$	817,754
Transactions With Related Parties [Table Text Block]	The following table shows ONEOK Partners’ transactions with us for the periods indicated:
			Years Ended December 31,
			2014			2013		2012
			(Thousands of dollars)
	Revenues		$	53,526		$	340,743	$	352,099
	Expenses
	Cost of sales and fuel		$	10,835		$	37,963	$	33,094
	Administrative and general expenses		330,541			265,448		246,050
	Total expenses		$	341,376		$	303,411	$	279,144

COMMITMENTS_AND_CONTINGENCIES_

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

SEGMENTS_Tables

SEGMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Segments	Operating Segment Information - The following tables set forth certain selected financial information for our operating segments for the periods indicated:
	Year Ended December 31, 2014	Natural Gas			Natural Gas			Natural Gas		Other and			Total
		Gathering and			Liquids (a)			Pipelines (b)		Eliminations (c)
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	1,478,729		$	10,329,609		$	329,801	$	3,426		$	12,141,565
	Sales to affiliated customers	41,214			—			12,312		—			53,526
	Intersegment revenues	1,447,665			215,772			8,343		(1,671,780		)	—
	Total revenues	$	2,967,608		$	10,545,381		$	350,456	$	(1,668,354	)	$	12,195,091
	Net margin	$	661,885		$	1,110,085		$	328,521	$	6,052		$	2,106,543
	Operating costs	257,658			296,402			111,037		9,790			674,887
	Depreciation and amortization	123,847			124,071			43,318		3,448			294,684
	Gain (loss) on sale of assets	219			(572		)	6,786		166			6,599
	Operating income	$	280,599		$	689,040		$	180,952	$	(7,020	)	$	1,143,571
	Equity earnings (loss) from investments	$	(56,141	)	$	27,326		$	69,818	$	—		$	41,003
	Investments in unconsolidated affiliates	$	254,818		$	490,582		$	387,253	$	—		$	1,132,653
	Total assets	$	4,727,201		$	8,082,692		$	1,823,917	$	670,750		$	15,304,560
	Noncontrolling interests in consolidated subsidiaries	$	4,251		$	163,671		$	—	$	3,245,846		$	3,413,768
	Capital expenditures	$	898,896		$	798,048		$	42,991	$	39,215		$	1,779,150
	(a) - The Natural Gas Liquids segment has regulated and nonregulated operations. The Natural Gas Liquids segment’s regulated operations had revenues of $695.9 million, of which $598.1 million was related to sales within the segment, net margin of $386.5 million and operating income of $196.1 million.
	(b) - The Natural Gas Pipelines segment has regulated and nonregulated operations. The Natural Gas Pipelines segment’s regulated operations had revenues of $290.0 million, net margin of $242.3 million and operating income of $106.5 million.
	(c) - Other and Eliminations includes assets and capital expenditures of discontinued operations of $28.0 million and $23.9 million, respectively.
	Year Ended December 31, 2013	Natural Gas			Natural Gas			Natural Gas		Other and			Total
		Gathering and			Liquids (a)			Pipelines (b)		Eliminations (c)
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	665,169		$	10,644,117		$	219,244	$	2,606		$	11,531,136
	Sales to affiliated customers	238,600			—			102,143		—			340,743
	Intersegment revenues	1,147,713			133,910			4,127		(1,285,750		)	—
	Total revenues	$	2,051,482		$	10,778,027		$	325,514	$	(1,283,144	)	$	11,871,879
	Net margin	$	500,627		$	869,938		$	285,719	$	(6,618	)	$	1,649,666
	Operating costs	193,293			236,638			101,182		10,473			541,586
	Depreciation and amortization	103,962			89,240			43,541		2,600			239,343
	Gain (loss) on sale of assets	436			843			10,602		—			11,881
	Operating income	$	203,808		$	544,903		$	151,598	$	(19,691	)	$	880,618
	Equity earnings from investments	$	23,493		$	21,978		$	65,046	$	—		$	110,517
	Investments in unconsolidated affiliates	$	333,179		$	491,856		$	404,803	$	—		$	1,229,838
	Total assets	$	3,949,813		$	6,938,633		$	1,817,675	$	5,035,360		$	17,741,481
	Noncontrolling interests in consolidated subsidiaries	$	4,521		$	—		$	—	$	2,502,808		$	2,507,329
	Capital expenditures	$	774,379		$	1,128,345		$	34,699	$	319,162		$	2,256,585
	(a) - The Natural Gas Liquids segment has regulated and nonregulated operations. The Natural Gas Liquids segment’s regulated operations had revenues of $534.8 million, of which $449.9 million was related to sales within the segment, net margin of $327.4 million and operating income of $190.5 million.
	(b) - The Natural Gas Pipelines segment has regulated and nonregulated operations. The Natural Gas Pipelines segment’s regulated operations had revenues of $246.9 million, net margin of $217.6 million and operating income of $90.5 million.
	(c) - Other and Eliminations includes assets and capital expenditures of discontinued operations of $4.4 billion and $292.1 million, respectively.
	Year Ended December 31, 2012	Natural Gas			Natural Gas			Natural Gas		Other and			Total
		Gathering and			Liquids (a)			Pipelines (b)		Eliminations (c)
		Processing
		(Thousands of dollars)
	Sales to unaffiliated customers	$	436,629		$	9,176,389		$	217,034	$	1,970		$	9,832,022
	Sales to affiliated customers	253,136			—			98,963		—			352,099
	Intersegment revenues	825,948			80,274			4,388		(910,610		)	—
	Total revenues	$	1,515,713		$	9,256,663		$	320,385	$	(908,640	)	$	10,184,121
	Net margin	$	455,170		$	907,340		$	286,060	$	(4,768	)	$	1,643,802
	Operating costs	164,033			223,844			101,899		1,949			491,725
	Depreciation and amortization	83,031			74,344			45,726		2,233			205,334
	Gain (loss) on sale of assets	2,278			(932		)	5,390		—			6,736
	Operating income	$	210,384		$	608,220		$	143,825	$	(8,950	)	$	953,479
	Equity earnings from investments	$	29,103		$	20,701		$	73,220	$	—		$	123,024
	Investments in unconsolidated affiliates	$	333,210		$	494,878		$	393,317	$	—		$	1,221,405
	Total assets	$	3,040,198		$	5,620,420		$	1,812,711	$	5,427,644		$	15,900,973
	Noncontrolling interests in consolidated subsidiaries	$	4,752		$	—		$	—	$	2,098,089		$	2,102,841
	Capital expenditures	$	566,126		$	968,549		$	25,383	$	306,095		$	1,866,153
	(a) - The Natural Gas Liquids segment has regulated and nonregulated operations. The Natural Gas Liquids segment’s regulated operations had revenues of $470.6 million, of which $397.7 million related to sales within the segment, net margin of $276.3 million and operating income of $162.8 million.
	(b) - The Natural Gas Pipelines segment has regulated and nonregulated operations. The Natural Gas Pipelines segment’s regulated operations had revenues of $251.5 million, net margin of $220.3 million and operating income of $99.3 million.
	(c) - Other and Eliminations includes assets and capital expenditures of discontinued operations of $4.5 billion and $280.3 million, respectively.

QUARTERLY_FINANCIAL_DATA_UNAUD1

QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly financial disclosure
		First		Second			Third			Fourth
	Year Ended December 31, 2014	Quarter		Quarter			Quarter			Quarter
		(Thousands of dollars except per share amounts)
	Total revenues	$	3,163,296	$	3,066,882		$	3,120,145		$	2,844,768
	Net margin	$	510,627	$	495,480		$	536,941		$	563,495
	Income from continuing operations	$	204,737	$	148,760		$	114,452		$	200,766
	Income (loss) from discontinued operations, net of tax	$	1,774	$	(8,009	)	$	(171	)	$	799
	Net income	$	206,511	$	140,751		$	114,281		$	201,565
	Net income attributable to ONEOK	$	93,515	$	61,590		$	64,458		$	94,544
	Earnings per share total
	Basic	$	0.45	$	0.29		$	0.31		$	0.45
	Diluted	$	0.45	$	0.29		$	0.31		$	0.45
		First		Second			Third			Fourth
	Year Ended December 31, 2013	Quarter		Quarter			Quarter			Quarter
		(Thousands of dollars except per share amounts)
	Total revenues	$	2,517,955	$	2,768,984		$	3,135,381		$	3,449,559
	Net margin	$	371,107	$	412,758		$	424,222		$	441,579
	Income from continuing operations	$	110,503	$	153,777		$	157,824		$	166,986
	Income (loss) from discontinued operations, net of tax	$	55,202	$	(74,282	)	$	(10,126	)	$	17,077
	Net income	$	165,705	$	79,495		$	147,698		$	184,063
	Net income attributable to ONEOK	$	112,521	$	919		$	62,356		$	90,737
	Earnings per share total
	Basic	$	0.55	$	—		$	0.3		$	0.44
	Diluted	$	0.54	$	—		$	0.3		$	0.43

SUMMARY_OF_SIGNIFICANT_ACCOUNT2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	Y
Entity [Line Items]
Ownership interest	37.80%	41.20%	43.40%	42.80%
Goodwill, Impairment Loss	$0	$0	$10,255,000
Impairment of Intangible Assets (Excluding Goodwill)	0	0	0
Impairment of Long-Lived Assets Held-for-use	0	0	0
Number of natural gas distribution services customers	2,000,000
Regulatory assets	6,100,000	383,600,000
Time period regulatory assets are being recovered (in years)	40
Number of years of service employees must work to be entitled to postretirement medical and life insurance benefits (in years)	5 years
Noncash charges	10,200,000
Distribution Regulated Segment [Member]
Entity [Line Items]
Regulatory assets		376,800,000
Distribution Regulated Segment [Member] | Pension Costs [Member]
Entity [Line Items]
Regulatory assets		341,100,000
Energy Services [Member]
Entity [Line Items]
Goodwill, Impairment Loss			$10,255,000

DISCONTINUED_OPERATIONS_Detail

DISCONTINUED OPERATIONS (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill, Impairment Loss									$0	$0	$10,255,000
Disposal Group, Including Discontinued Operation, Assets, Current	16,717,000				747,872,000				16,717,000	747,872,000
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents					3,748,000					3,748,000
Disposal Group, Including Discontinued Operation, Other Assets, Current					59,804,000					59,804,000
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment					3,065,551,000					3,065,551,000
Disposal Group, Including Discontinued Operation, Goodwill					157,953,000					157,953,000
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent	20,020,000				402,546,000				20,020,000	402,546,000
Disposal Group, Including Discontinued Operation, Assets	36,737,000				4,373,922,000				36,737,000	4,373,922,000
Disposal Group, Including Discontinued Operation, Liabilities, Current	44,901,000				455,688,000				44,901,000	455,688,000
Accumulated Charges Attributable To Exit Activities	73,800,000				122,000,000				73,800,000	122,000,000	0
Assets	15,304,560,000				17,741,481,000				15,304,560,000	17,741,481,000	15,900,973,000
Proceeds from Divestiture of Businesses and Interests in Affiliates											32,900,000
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax									0	0	13,517,000
Gain on sale of business, tax impact											8,300,000
Business Exit Costs									1,700,000	138,600,000
Effect on Future Cash Flows, Amount									45,000,000
Disposal Group, Including Discontinued Operation, Operating Expenses Related to Separation									23,000,000	9,400,000
Stockholders' Equity Note, Spinoff Transaction									-1,749,588,000
Proceeds from Divestiture of Businesses, Net of Cash Divested											22,500,000
Description and timing of discontinued operations											On February 1, 2012, we sold ONEOK Energy Marketing Company, our Natural Gas Distribution segmentbs retail natural gas marketing business, to Constellation Energy Group, Inc. for $22.5 million plus working capital.
Revenues									640,653,000	3,071,581,000	2,825,419,000
Cost of sales and fuel									555,541,000	2,431,565,000	2,116,734,000
Net margin									85,112,000	640,016,000	708,685,000
Operating costs									65,898,000	448,867,000	417,661,000
Operating income									7,860,000	46,115,000	150,251,000
Settlements of business exit costs									-51,800,000	-17,700,000
Accretion Expense									1,900,000	1,100,000
Disposal Group, Including Discontinued Operation, Depreciation and Amortization									11,354,000	145,034,000	130,518,000
Disposal Group, Including Discontinued Operation, Other Income									-895,000	2,619,000	1,586,000
Disposal Group, Including Discontinued Operation, Interest Expense									-5,005,000	-63,561,000	-64,668,000
Discontinued Operation, Tax Effect of Discontinued Operation									-7,567,000	2,698,000	-34,904,000
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	799,000	-171,000	-8,009,000	1,774,000	17,077,000	-10,126,000	-74,282,000	55,202,000	-5,607,000	-12,129,000	52,265,000
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net					455,529,000					455,529,000
Disposal Group, Including Discontinued Operation, Inventory					228,791,000					228,791,000
Disposal Group, Including Discontinued Operation, Current Maturities of Long-Term Debt					6,000					6,000
Disposal Group, Including Discontinued Operation, Accounts Payable					246,072,000					246,072,000
Disposal Group, Including Discontinued Operation, Other Liabilities, Current					209,610,000					209,610,000
Disposal Group, Including Discontinued Operation, Long Term Debt Excluding Current Portion					1,318,000					1,318,000
Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities, Noncurrent					791,700,000					791,700,000
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent	36,424,000				255,212,000				36,424,000	255,212,000
Disposal Group, Including Discontinued Operation, Liabilities	81,325,000				1,503,918,000				81,325,000	1,503,918,000
Natural Gas Distribution [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents					3,535,000					3,535,000
Disposal Group, Including Discontinued Operation, Other Assets, Current					30,328,000					30,328,000
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment					3,065,272,000					3,065,272,000
Disposal Group, Including Discontinued Operation, Goodwill					157,953,000					157,953,000
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent					402,161,000					402,161,000
Disposal Group, Including Discontinued Operation, Assets					4,193,591,000					4,193,591,000
Assets												4,300,000,000
Liabilities												2,600,000,000
Accounts Receivable, Related Parties, Current					130,000,000					130,000,000
Notes Receivable, Related Parties, Noncurrent					1,000,000,000					1,000,000,000
Stockholders' Equity Note, Spinoff Transaction				1,700,000,000
Description and timing of discontinued operations									On January 31, 2014, we completed the separation of ONE Gas. ONE Gas consists of our former natural gas distribution business that includes Kansas Gas Service, Oklahoma Natural Gas and Texas Gas Service. ONEOK shareholders of record at the close of business on January 21, 2014, retained their shares of ONEOK stock and received one share of ONE Gas stock for every four shares of ONEOK stock owned in a transaction that was tax-free to ONEOK and its shareholders. ONE Gas shares were distributed following the close of business on January 31, 2014.
Revenues									287,249,000	1,689,945,000	1,404,248,000
Cost of sales and fuel									190,893,000	876,944,000	646,220,000
Net margin									96,356,000	813,001,000	758,028,000
Operating costs									60,847,000	436,281,000	400,247,000
Operating income									24,474,000	231,962,000	227,623,000
Disposal Group, Including Discontinued Operation, Depreciation and Amortization									11,035,000	144,758,000	130,158,000
Disposal Group, Including Discontinued Operations, Goodwill Impairment											0
Disposal Group, Including Discontinued Operation, Other Income									-888,000	2,484,000	1,439,000
Disposal Group, Including Discontinued Operation, Interest Expense									-4,592,000	-61,366,000	-60,794,000
Discontinued Operation, Tax Effect of Discontinued Operation									-16,415,000	-64,307,000	-63,647,000
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest									2,579,000	108,773,000	104,621,000
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net					368,214,000					368,214,000
Disposal Group, Including Discontinued Operation, Inventory					166,128,000					166,128,000
Disposal Group, Including Discontinued Operation, Current Maturities of Long-Term Debt					6,000					6,000
Disposal Group, Including Discontinued Operation, Accounts Payable					168,785,000					168,785,000
Disposal Group, Including Discontinued Operation, Other Liabilities, Current					168,964,000					168,964,000
Disposal Group, Including Discontinued Operation, Long Term Debt Excluding Current Portion					1,318,000					1,318,000
Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities, Noncurrent					826,921,000					826,921,000
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent					184,214,000					184,214,000
Disposal Group, Including Discontinued Operation, Liabilities					1,350,208,000					1,350,208,000
Energy Services [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents					213,000					213,000
Disposal Group, Including Discontinued Operation, Other Assets, Current					29,476,000					29,476,000
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment					279,000					279,000
Disposal Group, Including Discontinued Operation, Goodwill					0					0
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent					385,000					385,000
Disposal Group, Including Discontinued Operation, Assets					180,331,000					180,331,000
Accounts Receivable, Related Parties, Current					25,100,000					25,100,000
Notes Receivable, Related Parties, Noncurrent					21,400,000					21,400,000
Description and timing of discontinued operations									On March 31, 2014, we completed the accelerated wind down of our energy services business. We executed agreements in 2013 to release a significant portion of our nonaffiliated natural gas transportation and storage contracts to third parties between July 1 and December 31, 2013.
Revenues									353,404,000	1,381,636,000	1,421,171,000
Cost of sales and fuel									364,648,000	1,554,621,000	1,470,514,000
Net margin									-11,244,000	-172,985,000	-49,343,000
Operating costs									5,051,000	12,586,000	17,414,000
Operating income									-16,614,000	-185,847,000	-77,372,000
Disposal Group, Including Discontinued Operation, Depreciation and Amortization									319,000	276,000	360,000
Disposal Group, Including Discontinued Operations, Goodwill Impairment											10,255,000
Disposal Group, Including Discontinued Operation, Other Income									-7,000	135,000	147,000
Disposal Group, Including Discontinued Operation, Interest Expense									-413,000	-2,195,000	-3,874,000
Discontinued Operation, Tax Effect of Discontinued Operation									8,848,000	67,005,000	28,743,000
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest									-8,186,000	-120,902,000	-52,356,000
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net					87,315,000					87,315,000
Disposal Group, Including Discontinued Operation, Inventory					62,663,000					62,663,000
Disposal Group, Including Discontinued Operation, Current Maturities of Long-Term Debt					0					0
Disposal Group, Including Discontinued Operation, Accounts Payable					77,287,000					77,287,000
Disposal Group, Including Discontinued Operation, Other Liabilities, Current					40,646,000					40,646,000
Disposal Group, Including Discontinued Operation, Long Term Debt Excluding Current Portion					0					0
Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities, Noncurrent					-35,221,000					-35,221,000
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent					70,998,000					70,998,000
Disposal Group, Including Discontinued Operation, Liabilities					153,710,000					153,710,000
2015 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Effect on Future Cash Flows, Amount									23,000,000
2016 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Effect on Future Cash Flows, Amount									11,000,000
2017 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Effect on Future Cash Flows, Amount									6,000,000
2018 - 2023 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Effect on Future Cash Flows, Amount									5,000,000
Oneok Partners [Member] | Natural Gas Distribution [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues									7,500,000	64,500,000	49,400,000
Oneok Partners [Member] | Energy Services [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party									$46,000,000	$276,300,000	$299,900,000

ACQUISITIONS_ACQUISITIONS_Deta

ACQUISITIONS ACQUISITIONS (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2014
		MMcf
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	$13,839,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	961,520,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		103,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	987,860,000	212,889,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		92,000,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest	800,934,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	9,132,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other	3,369,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable	-8,621,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other	-1,553,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	-10,174,000
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	-162,913,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	814,773,000
Business Combination, Cash Received	-13,839,000
West Texas LPG and Mesquite Systems [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest	800,000,000
Business Acquisition, Effective Date of Acquisition	30-Nov-14
Sage Creek Natural Gas Gathering And Processing [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest		304,889,000
Business Acquisition, Effective Date of Acquisition		30-Sep-13
Processing capacity of natural gas processing plant, per day		50
Maysville Natural Gas Processing Facility [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest		90,000,000
Business Acquisition, Effective Date of Acquisition		1-Dec-13
Business Acquisition, Percentage of Voting Interests Acquired		30.00%
Total Ownership Percentage of a Business		100.00%
West Texas LPG Pipeline Limited Partnership [Member]
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	80.00%
Mesquite Pipeline [Member]
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	100.00%
Minimum [Member] | Sage Creek Natural Gas Gathering And Processing [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		20 years
Maximum [Member] | Sage Creek Natural Gas Gathering And Processing [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		30 years
Regulated Operation [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	807,601,000
Nonregulated Operation [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	153,919,000
Pipelines [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		59,174,000
Gas Gathering and Processing Equipment [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		50,595,000
Manufacturing Facility [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		120,000
Natural Gas Gathering And Processing [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		40,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		131,844,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		20,000,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest		151,844,000
Natural Gas Gathering And Processing [Member] | Pipelines [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		41,129,000
Natural Gas Gathering And Processing [Member] | Gas Gathering and Processing Equipment [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		50,595,000
Natural Gas Gathering And Processing [Member] | Manufacturing Facility [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		120,000
Natural Gas Liquids [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		63,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		81,045,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		72,000,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest		153,045,000
Natural Gas Liquids [Member] | Pipelines [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		18,045,000
Natural Gas Liquids [Member] | Gas Gathering and Processing Equipment [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		0
Natural Gas Liquids [Member] | Manufacturing Facility [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		0
Partnership Credit Agreement [Member]
Business Acquisition [Line Items]
Maximum Amount Of Commercial Paper	$1,700,000,000		$1,200,000,000

FAIR_VALUE_MEASUREMENTS_Part_1

FAIR VALUE MEASUREMENTS - Part 1 (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Commodity contracts
Cash collateral held	$24,800,000	$0
Cash collateral posted	0	0
Fair Value, Measurements, Recurring [Member]
Commodity contracts
Financial contracts	17,255,000	4,723,000
Financial Instruments, Owned, Physical Commodities, at Fair Value	9,922,000	1,077,000
Interest Rate Derivative Assets, at Fair Value	2,288,000	54,503,000
Total derivatives	29,465,000	60,303,000
Available-for-sale investment securities	1,773,000	1,569,000
Assets, Fair Value Disclosure	31,238,000	61,872,000
Commodity contracts
Financial contracts	0	-3,361,000
Physical contracts	-23,000	-2,517,000
Interest Rate Derivative Liabilities, at Fair Value	-44,843,000
Total liabilities	-44,866,000	-5,878,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Commodity contracts
Financial contracts	42,880,000	0
Financial Instruments, Owned, Physical Commodities, at Fair Value	0	0
Interest Rate Derivative Assets, at Fair Value	0	0
Total derivatives	42,880,000	0
Available-for-sale investment securities	1,773,000	1,569,000
Assets, Fair Value Disclosure	44,653,000	1,569,000
Commodity contracts
Financial contracts	-169,000	0
Physical contracts	0	0
Interest Rate Derivative Liabilities, at Fair Value	0
Total liabilities	-169,000	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Commodity contracts
Financial contracts	0	3,657,000
Financial Instruments, Owned, Physical Commodities, at Fair Value	0	0
Interest Rate Derivative Assets, at Fair Value	2,288,000	54,503,000
Total derivatives	2,288,000	58,160,000
Available-for-sale investment securities	0	0
Assets, Fair Value Disclosure	2,288,000	58,160,000
Commodity contracts
Financial contracts	0	-2,953,000
Physical contracts	0	0
Interest Rate Derivative Liabilities, at Fair Value	-44,843,000
Total liabilities	-44,843,000	-2,953,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Commodity contracts
Financial contracts	354,000	2,812,000
Financial Instruments, Owned, Physical Commodities, at Fair Value	9,922,000	2,023,000
Interest Rate Derivative Assets, at Fair Value	0	0
Total derivatives	10,276,000	4,835,000
Available-for-sale investment securities	0	0
Assets, Fair Value Disclosure	10,276,000	4,835,000
Commodity contracts
Financial contracts	-968,000	-2,154,000
Physical contracts	-23,000	-3,463,000
Interest Rate Derivative Liabilities, at Fair Value	0
Total liabilities	-991,000	-5,617,000
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member]
Commodity contracts
Financial contracts	43,234,000	6,469,000
Financial Instruments, Owned, Physical Commodities, at Fair Value	9,922,000	2,023,000
Interest Rate Derivative Assets, at Fair Value	2,288,000	54,503,000
Total derivatives	55,444,000	62,995,000
Available-for-sale investment securities	1,773,000	1,569,000
Assets, Fair Value Disclosure	57,217,000	64,564,000
Commodity contracts
Financial contracts	-1,137,000	-5,107,000
Physical contracts	-23,000	-3,463,000
Interest Rate Derivative Liabilities, at Fair Value	-44,843,000
Total liabilities	-46,003,000	-8,570,000
Fair Value, Measurements, Recurring [Member] | Netting [Member]
Commodity contracts
Financial contracts	-25,979,000	-1,746,000
Financial Instruments, Owned, Physical Commodities, at Fair Value	0	-946,000
Interest Rate Derivative Assets, at Fair Value	0	0
Total derivatives	-25,979,000	-2,692,000
Available-for-sale investment securities	0	0
Assets, Fair Value Disclosure	-25,979,000	-2,692,000
Commodity contracts
Financial contracts	1,137,000	1,746,000
Physical contracts	0	946,000
Interest Rate Derivative Liabilities, at Fair Value	0
Total liabilities	1,137,000	2,692,000
Natural Gas Liquids [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Nonmonetary Notional Amount	0	0
Reported Value Measurement [Member]
Commodity contracts
Long-term Debt	7,203,579,000	7,800,000,000
Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	$7,500,000,000	$8,200,000,000

FAIR_VALUE_MEASUREMENTS_FAIR_V

FAIR VALUE MEASUREMENTS FAIR VALUE MEASUREMENTS - Part 2 (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Total realized/unrealized gains (losses): [Abstract]
Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) relating to assets and liabilities at end of period	$31	$959
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	0	0
Derivative Financial Instruments Assets Liabilities Net [Member]
Fair Value, Assets And Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net assets (liabilities) at beginning of period	-782	-2,423
Total realized/unrealized gains (losses): [Abstract]
Included in Earnings	-927	959
Included in other comprehensive income (loss)	7,260	682
Purchases, Issuances and Settlements	3,734	0
Net assets (liabilities) at end of period	$9,285	($782)

RISK_MANAGEMENT_AND_HEDGING_AC2

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

RISK_MANAGEMENT_AND_HEDGING_AC3

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

RISK_MANAGEMENT_AND_HEDGING_AC4

RISK MANAGEMENT AND HEDGING ACTIVITIES USING DERIVATIVES - Part 3 (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain Loss On Cash Flow Hedges Net Of Tax Accumulated Other Comprehensive Income Loss	$12,800,000
Amount recognized in the next 12 months	12,800,000
Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion)	-16,225,000	8,842,000
Interest Expense Savings From Amortization Of Terminated Swaps	1,700,000	1,700,000	1,700,000
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Price Risk Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net		8,000,000
Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion)	-68,336,000	31,183,000	33,427,000
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion)	-55,821,000	-9,831,000	59,826,000
Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	-4,600,000	0	0
Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Tax	3,100,000
Income (Loss) From Discontinued Operations [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Inventory Write-down		10,100,000
Derivative, Loss on Derivative			29,900,000
Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of accumulated other comprehensive income (loss) attributable primarily to settled interest-rate swaps.	-38,400,000
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	-4,700,000
Continuing Operations [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion)	-64,639,000	32,141,000	17,333,000
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion)	-43,018,000	-12,871,000	54,371,000
Continuing Operations [Member] | Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion)	32,354,000	-14,475,000	46,804,000
Continuing Operations [Member] | Commodity Contract [Member] | Sales [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion)	-21,052,000	1,689,000	61,526,000
Continuing Operations [Member] | Interest Rate Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion)	-96,993,000	46,616,000	-29,471,000
Continuing Operations [Member] | Interest Rate Contract [Member] | Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion)	-21,966,000	-14,560,000	-7,155,000
Discontinued Operations [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in other comprehensive income (loss) on derivatives (effective portion)	-3,697,000	-958,000	16,094,000
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion)	-12,803,000	3,040,000	5,455,000
Discontinued Operations [Member] | Commodity Contract [Member] | Sales [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion)	-12,803,000	17,360,000	79,336,000
Discontinued Operations [Member] | Commodity Contract [Member] | Cost of Sales [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) reclassified from accumulated other comprehensive income (loss) into net income on derivatives (effective portion)	$0	($14,320,000)	($73,881,000)

PROPERTY_PLANT_AND_EQUIPMENT_P

PROPERTY, PLANT AND EQUIPMENT - Part 1 (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Construction in Progress Expenditures Incurred but Not yet Paid	$187,200,000	$237,200,000	$220,200,000
Property, plant and equipment by type [Abstract]
Property, plant and equipment	13,602,647,000	10,970,256,000
Accumulated Depreciation	-1,940,210,000	-1,738,302,000
Net property, plant and equipment	11,662,437,000	9,231,954,000
Non-Regulated Property, Plant and Equipment [Member]
Property, plant and equipment by type [Abstract]
Accumulated Depreciation	-1,221,387,000	-1,090,268,000
Non-Regulated Property, Plant and Equipment [Member] | Gathering pipelines and related equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	2,449,343,000	2,173,271,000
Non-Regulated Property, Plant and Equipment [Member] | Processing and fractionation and related equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	2,880,572,000	2,295,983,000
Non-Regulated Property, Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	478,276,000	362,704,000
Non-Regulated Property, Plant and Equipment [Member] | Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	518,585,000	302,718,000
Non-Regulated Property, Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	364,976,000	314,919,000
Non-Regulated Property, Plant and Equipment [Member] | Construction Work in Process [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	1,236,138,000	1,085,185,000
Regulated Property Plant and Equipment [Member]
Property, plant and equipment by type [Abstract]
Accumulated Depreciation	-718,823,000	-648,034,000
Regulated Property Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	115,799,000	135,922,000
Regulated Property Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	63,424,000	53,315,000
Regulated Property Plant and Equipment [Member] | Construction Work in Process [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	194,700,000	776,261,000
Regulated Property Plant and Equipment [Member] | Natural Gas Transmission Pipelines and Regulated Equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	1,478,035,000	1,420,517,000
Regulated Property Plant and Equipment [Member] | Natural Gas Liquids Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Property, plant and equipment	$3,822,799,000	$2,049,461,000
Minimum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Gathering pipelines and related equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Minimum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Processing and fractionation and related equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	3 years
Minimum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Minimum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Minimum [Member] | Non-Regulated Property, Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	2 years
Minimum [Member] | Regulated Property Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Minimum [Member] | Regulated Property Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	2 years
Minimum [Member] | Regulated Property Plant and Equipment [Member] | Natural Gas Transmission Pipelines and Regulated Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Minimum [Member] | Regulated Property Plant and Equipment [Member] | Natural Gas Liquids Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	5 years
Maximum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Gathering pipelines and related equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	40 years
Maximum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Processing and fractionation and related equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	40 years
Maximum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	54 years
Maximum [Member] | Non-Regulated Property, Plant and Equipment [Member] | Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	54 years
Maximum [Member] | Non-Regulated Property, Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	60 years
Maximum [Member] | Regulated Property Plant and Equipment [Member] | Storage and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	54 years
Maximum [Member] | Regulated Property Plant and Equipment [Member] | General plant and other [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	53 years
Maximum [Member] | Regulated Property Plant and Equipment [Member] | Natural Gas Transmission Pipelines and Regulated Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	77 years
Maximum [Member] | Regulated Property Plant and Equipment [Member] | Natural Gas Liquids Transmission Pipelines and Related Equipment [Member]
Property, plant and equipment by type [Abstract]
Estimated Useful Lives	80 years
Natural Gas Pipelines [Member] | Regulated Property Plant and Equipment [Member]
Property, Plant and Equipment [Line Items]
Average Depreciation Rate	2.00%	2.00%	1.90%
Natural Gas Liquids [Member] | Regulated Property Plant and Equipment [Member]
Property, Plant and Equipment [Line Items]
Average Depreciation Rate	2.10%	2.20%	2.20%

GOODWILL_AND_INTANGIBLE_ASSETS2

GOODWILL AND INTANGIBLE ASSETS (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Goodwill, Impairment Loss	$0	$0	$10,255,000
Goodwill	525,535,000	525,535,000
Amortization expense for intangible assets	11,800,000	8,700,000	7,700,000
Gross Intangible Assets	567,215,000	565,215,000
Accumulated Amortization	-78,010,000	-66,188,000
Net Intangible Assets	489,205,000	499,027,000
Future amortization expense for next five years [Abstract]
Future amortization expense, year one	11,800,000
Future amortization expense, year two	11,800,000
Future amortization expense, year three	11,800,000
Future amortization expense, year four	11,800,000
Future amortization expense, year five	11,800,000
Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Goodwill, Acquired During Period	72,000,000
Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Goodwill, Acquired During Period	20,000,000
Oneok Partners [Member]
Segment Reporting Information [Line Items]
Net Intangible Assets	333,600,000	343,500,000
Minimum [Member]
Segment Reporting Information [Line Items]
Finite-Lived Intangible Asset, Useful Life	20 years
Maximum [Member]
Segment Reporting Information [Line Items]
Finite-Lived Intangible Asset, Useful Life	40 years
Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Goodwill	122,291,000	122,291,000
Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Goodwill	268,544,000	268,544,000
Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Goodwill	$134,700,000	$134,700,000

CREDIT_FACILITIES_AND_SHORTTER1

CREDIT FACILITIES AND SHORT-TERM NOTES PAYABLE (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Mar. 31, 2014	Jan. 31, 2014	Dec. 31, 2013
Partnership Credit Agreement [Member]
Line of Credit Facility [Line Items]
Interest Rate Description	borrowings, if any, will accrue at LIBOR plus 117.5 basis points
Line Of Credit Facility, Annual Facility Fee Description	the annual facility fee is 20 basis points
Commercial paper	$1,100,000,000
Letters of credit issued	14,000,000
Indebtedness To Adjusted Ebitda Maximum	5
Indebtedness To Adjusted Ebitda From Acquisitions Maximum	5.5
Indebtedness To Adjusted Ebitda Current	3.7
Acquisition price threshold for increase in permitted debt to EBITDA covenant ratio	25,000,000
Partnership Credit Agreement sublimit for issuance of standby letters of credit	100,000,000
Line of credit facility swingline subfacility	150,000,000
Maximum Amount Of Commercial Paper	1,700,000,000	1,200,000,000
Option to increase borrowing capacity	2,400,000,000
Short-term Bank Loans and Notes Payable	0
ONEOK Credit Agreement [Member]
Line of Credit Facility [Line Items]
Interest Rate Description	Borrowings, if any, will accrue at LIBOR plus 125 basis points
Line Of Credit Facility, Annual Facility Fee Description	Annual facility fee is 25 basis points
Commercial paper			600,500,000
Weighted-average interest rate on short-term debt outstanding (in hundredths)	0.00%
Letters of credit issued	1,900,000
Indebtedness To Adjusted Ebitda Maximum	4
Write off of Deferred Debt Issuance Cost	2,900,000
Indebtedness To Adjusted Ebitda Current	2.3
Partnership Credit Agreement sublimit for issuance of standby letters of credit	50,000,000
Line of credit facility swingline subfacility	50,000,000
Maximum borrowing capacity	300,000,000			1,200,000,000
Option to increase borrowing capacity	$500,000,000

LONGTERM_DEBT_Details

LONG-TERM DEBT (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2012	Dec. 31, 2013	Jan. 31, 2014
Debt Instrument [Line Items]
Long-term Debt, Gross		$7,194,573,000		$7,754,857,000
Unamortized portion of terminated swaps		23,622,000		25,340,000
Unamortized debt discount		-14,616,000		-15,890,000
Current maturities		-10,650,000		-10,650,000
2014		10,700,000
2015		1,110,700,000
2016		410,700,000
2017		435,700,000
2018		510,700,000
Long-term debt		7,192,929,000		7,753,657,000
Oneok [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		1,135,016,000		1,687,649,000
2014		3,000,000
2015		3,000,000
2016		3,000,000
2017		3,000,000
2018		3,000,000
Oneok [Member] | Notes Payables due 2015 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		0		400,000,000
Interest Rate (in hundredths)		5.20%		5.20%
Extinguishment of Debt, Amount	400,000,000
Early Repayment of Senior Debt	430,100,000
Gains (Losses) on Extinguishment of Debt		24,800,000
Oneok [Member] | Note Payable from Public Offering Due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		547,397,000	700,000,000	700,000,000
Interest Rate (in hundredths)		4.25%	4.25%
Net proceeds from public offering			694,300,000
Extinguishment of Debt, Amount	152,500,000
Early Repayment of Senior Debt	150,000,000
Oneok [Member] | Notes Payables due 2035 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		400,000,000		400,000,000
Interest Rate (in hundredths)		6.00%
Oneok [Member] | Note Payables 1 due 2028 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		87,619,000		87,649,000
Interest Rate (in hundredths)		6.50%
Oneok [Member] | Note Payables 2 due 2028 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		100,000,000		100,000,000
Interest Rate (in hundredths)		6.88%
ONE Gas [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross					1,200,000,000
Net proceeds from public offering	1,190,000,000
Related Party Transaction, Amounts of Transaction	1,130,000,000
ONE Gas [Member] | Note Payables 2 due 2028 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross					300,000,000
Interest Rate (in hundredths)					2.07%
ONE Gas [Member] | Note Payables due 2024 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross					300,000,000
Interest Rate (in hundredths)					3.61%
ONE Gas [Member] | Note Payables due 2044 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross					600,000,000
Interest Rate (in hundredths)					4.66%
Guardian Pipeline [Member] | Guardian Pipeline [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date		30-Sep-22
MasterShelfAgreementInitiationDate		8-Nov-01
Guardian Pipeline [Member] | Notes Payables 1 due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		59,557,000		67,208,000
Long-term Debt, Weighted Average Interest Rate		7.85%
Debt instrument covenant description		Guardian Pipelinebs senior notes contain financial covenants that require the maintenance of certain financial ratios as defined in the master shelf agreement based on Guardian Pipelinebs financial position and results of operations.B B Upon any breach of these covenants, all amounts outstanding under the master shelf agreement may become due and payable immediately.
2014		7,700,000
2015		7,700,000
2016		7,700,000
2017		7,700,000
2018		7,700,000
Debt Instrument, Covenant Compliance		At December 31, 2014, Guardian Pipeline was in compliance with its financial covenants.
Partnership Interest [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		6,059,557,000		6,067,208,000
2014		0
2015		1,100,000,000
2016		400,000,000
2017		425,000,000
2018		500,000,000
Partnership Interest [Member] | Note Payable from Public Offering Due 2023 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		425,000,000		425,000,000
Interest Rate (in hundredths)				5.00%
Debt Instrument, Face Amount				425,000,000
Partnership Interest [Member] | Note Payable from Public Offering Due 2043 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		400,000,000		400,000,000
Interest Rate (in hundredths)				6.20%
Debt Instrument, Face Amount				400,000,000
Partnership Interest [Member] | Notes Payables due 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		500,000,000		500,000,000
Partnership Interest [Member] | Note Payable from Public Offering Due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		650,000,000		650,000,000
Interest Rate (in hundredths)		3.25%
Partnership Interest [Member] | Notes Payable due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		450,000,000		450,000,000
Partnership Interest [Member] | Note Payable from Public Offering Due 2017 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		400,000,000		400,000,000
Interest Rate (in hundredths)			2.00%
Debt Instrument, Face Amount			400,000,000
Partnership Interest [Member] | Notes Payables due 2012 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross			350,000,000
Interest Rate (in hundredths)			5.90%
Debt Instrument, Face Amount			350,000,000
Partnership Interest [Member] | Note Payable from Public Offering Due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		900,000,000		900,000,000
Interest Rate (in hundredths)			3.38%
Debt Instrument, Face Amount			900,000,000
Partnership Interest [Member] | Notes Payables due 2036 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		600,000,000		600,000,000
Partnership Interest [Member] | Notes Payables due 2037 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		600,000,000		600,000,000
Partnership Interest [Member] | Note Payable from Public Offering Due 2041 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		650,000,000		650,000,000
Partnership Interest [Member] | Note Payable from Public Offering Due 2018 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		425,000,000		425,000,000
Interest Rate (in hundredths)				3.20%
Debt Instrument, Face Amount				425,000,000
Senior Notes [Member] | Oneok [Member]
Debt Instrument [Line Items]
Debt instrument call feature		ONEOK may redeem the senior notes due 2028 (6.875 percent) and 2035, in whole or in part, at any time prior to their maturity at a redemption price equal to the principal amount, plus accrued and unpaid interest and a make-whole premium. ONEOK may redeem the senior notes due 2028 (6.5 percent), in whole or in part, at any time prior to their maturity at a redemption price equal to the principal amount, plus accrued and unpaid interest.B B ONEOK may redeem the remaining balance of its 4.25 percent senior notes due 2022 at a redemption price equal to the principal amount, plus accrued and unpaid interest, starting three months before the maturity date.B B Prior to this date, ONEOK may redeem these senior notes on the same basis as its other senior notes due 2028 (6.875 percent) and 2035.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 ONEOKbs senior notes due 2022, 2028 and 2035 are senior unsecured obligations, ranking equally in right of payment with all of ONEOKbs existing and future unsecured senior indebtedness.
Debt instrument covenant description		The indentures governing ONEOKbs senior notes due 2028 (6.5 percent and 6.875 percent) include an event of default upon acceleration of other indebtedness of $15 million or more, and the indentures governing the senior notes due 2022 and 2035 include an event of default upon the 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 the outstanding senior notes due 2022, 2028 and 2035 to declare those senior notes immediately due and payable in full.B
Senior Notes [Member] | Partnership Interest [Member]
Debt Instrument [Line Items]
Debt instrument call feature		We may redeem our senior notes due 2016 (6.15 percent), 2019, 2036 and 2037, in whole or in part, at any time prior to their maturity at a redemption price equal to the principal amount, plus accrued and unpaid interest and a make-whole premium. The redemption price will never be less than 100 percent of the principal amount of the respective note plus accrued and unpaid interest to the redemption date. We may redeem our senior notes due 2017 and our senior notes due 2022 at par starting one month and three months, respectively, before their maturity dates. We may redeem our senior notes due 2016 (3.25 percent) and 2041 at a redemption price equal to the principal amount, plus accrued and unpaid interest, starting one month and six months, respectively, before their maturity dates. Prior to these dates, we may redeem these notes, in whole or in part, at a redemption price equal to the principal amount, plus accrued and unpaid interest and a make-whole premium. We may redeem our senior notes due 2018, 2023 and 2043 at par, plus accrued and unpaid interest to the redemption date, starting one month, three months, and six months, respectively, before their maturity dates. Prior to these dates, we may redeem these notes, in whole or in part, at a redemption price equal to the principal amount, plus accrued and unpaid interest and a make-whole premium. The redemption price will never be less than 100 percent of the principal amount of the respective note plus accrued and unpaid interest to the redemption date.
Debt instrument covenant description		Our senior notes are governed by an indenture, dated as of September 25, 2006, between us and Wells Fargo Bank, N.A., the trustee, as supplemented.B B The indenture does not limit the aggregate principal amount of debt securities that may be issued and provides that debt securities may be issued from time to time in one or more additional series.B B The indenture contains covenants including, among other provisions, limitations on our ability to place liens on our property or assets and to sell and lease back our property.B B The indenture includes an event of default upon acceleration of other indebtedness of $100 million or more.B B Such events of default would entitle the trustee or the holders of 25 percent in aggregate principal amount of any of our outstanding senior notes to declare those notes immediately due and payable in full.
Debt Instrument, Face Amount			1,300,000,000	1,250,000,000
Net proceeds from public offering			1,290,000,000	1,240,000,000
Northern Border Pipeline [Member]
Debt Guarantee [Abstract]
Net ownership percentage		50.00%
Partnership Credit Agreement [Member]
Debt Instrument [Line Items]
Line Of Credit Facility Option To Increase Borrowing Capacity		2,400,000,000
Maximum Amount Of Commercial Paper	$1,200,000,000	$1,700,000,000

EQUITY_Details

EQUITY (Details) (USD $)	3 Months Ended												12 Months Ended			3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2015
Accelerated share repurchases price paid															$150
Accelerated share repurchases (in shares)															3.4
Common stock authorized and unreserved common stock available for issuance. (in shares)	363												363
Dividends paid													$443.80	$304.70	$262
Dividend paid (in dollars per share)	$0.59	$0.57	$0.56	$0.40	$0.38	$0.38	$0.36	$0.36	$0.33	$0.33	$0.31	$0.31	$2.13	$1.48	$1.27
Dividend declared (in dollars per share)													$2.13	$1.48	$1.27
Subsequent Event [Member]
Dividend paid (in dollars per share)																$0.61

ACCUMULATED_OTHER_COMPREHENSIV2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other comprehensive income (loss) before reclassifications	($16,225)	$8,842
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments, Net of Tax	98	-177
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	33,987	-37,144
Other comprehensive income (loss) before reclassifications	-50,114	45,809
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	0	0
Other Comprehensive Income (Loss), Reclassification Adjustment included in Net Income, Net of Tax	32,359	49,002
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent	5,819	11,862
Income tax expense	-14,098	-1,905	10,327
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax	41,723	7,926	-49,499
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax	10,315	45,982
Balance of accumulated other comprehensive income (loss) [Abstract]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	-37,349	-43,168	-55,030
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	955	857	1,034
Pension and Postretirement Benefit Plan Obligations	-99,959	-79,676	-162,802
Accumulated Other Comprehensive Income (Loss)	-136,353	-121,987	-216,798
Other comprehensive income (loss) attributable to ONEOK [Abstract]
Unrealized Holding Gains (Losses) on Investment Securities	98	-177	47
Pension and Postretirement Benefit Plan Obligations	23,672	-83,126	11,061
Accumulated Other Comprehensive Income (Loss)	-17,755	94,811
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges Transferred to Separated Entity, Effect Net of Tax	0
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Amount Transferred to Separated Entity, Net of Tax	0
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Amount Transferred to Separated Entity, Net of Tax	3,389
Accumulated Other Comprehensive Income (Loss), Amount Transferred to Separated Entity, Net of Tax, Total	3,389
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax	22,044	3,020
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Total before tax [Member]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	43,018	12,871
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Tax benefit [Member]
Income tax expense	-8,977	-3,081
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Net of tax [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax	41,723	7,926
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Discontinued Operations [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax	7,682	-1,864
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Commodity Contract [Member] | Sales [Member]
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	21,052	-1,689
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion	21,966	14,560
Accumulated Defined Benefit Plans Adjustment [Member]
Defined Benefit Plan, Amortization of Net Gains (Losses)	15,914	21,407
Defined Benefit Plan, Amortization of Net Prior Service Cost (Credit)	-1,469	-1,560
Amortization of unrecognized net asset at adoption	0	49
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	14,445	19,896
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, Tax	-5,778	-7,958
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax	10,315	45,982
Accumulated Defined Benefit Plans Adjustment [Member] | Discontinued Operations [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax	1,648	34,044
Accumulated Defined Benefit Plans Adjustment [Member] | Continuing Operations [Member]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Net of Tax	8,667	11,938
Cash Flow Hedging [Member]
Other comprehensive income (loss) before reclassifications	-68,336	31,183	33,427
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-55,821	-9,831	59,826
Cash Flow Hedging [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Net of tax [Member]
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax	34,041	9,790
Cash Flow Hedging [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] | Net income attributable to noncontrolling interest [Member]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Noncontrolling Interest	$19,679	$4,906

EARNINGS_PER_SHARE_Details

EARNINGS PER SHARE (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic EPS from continuing operations [Abstract]
Income from continuing operations attributable to ONEOK available for common stock									$319,714	$278,662	$294,837
Shares									209,391	206,044	206,140
Per share amount	$0.45	$0.31	$0.29	$0.45	$0.44	$0.30	$0	$0.55	$1.53	$1.35	$1.43
Diluted EPS from continuing operations [Abstract]
Effect of options and other dilutive securities									0	0	0
Effect of options and other dilutive securities, shares									1,036	3,651	4,570
Income from continuing operations attributable to ONEOK available for common stock and common stock equivalents									$319,714	$278,662	$294,837
Shares									210,427	209,695	210,710
Per share amount	$0.45	$0.31	$0.29	$0.45	$0.43	$0.30	$0	$0.54	$1.52	$1.33	$1.40

SHAREBASED_PAYMENTS_Details

SHARE-BASED PAYMENTS (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividends Paid Prior to Vesting on the Restricted Stock Units Granted Prior to 2013	$0
Dividends and Interest Paid	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0	0	0
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding awards vesting period (in years)	3 years
Weighted Average Price [Abstract]
Nonvested beginning balance (in dollars per share)	$35.27
Granted (in dollars per share)	$58.23	47.46	36.65
Released to participants (in dollars per share)	$29.07
Forfeited (in dollars per share)	$43.96
Nonvested ending balance (in dollars per share)	$41.54	35.27
Fair value of shares granted	8,463,000	7,940,000	11,030,000
Unrecognized compensation cost related to our nonvested restricted stock unit awards	7,900,000
Period over which compensation cost related to nonvested restricted stock will be recognized (in years)	1 year 9 months 3 days
Restricted stock units and performance stock units activity [Roll forward]
Nonvested beginning balance (in shares)	776,596
Granted (in shares)	145,342
Released to participants (in shares)	-366,302
Forfeited (in shares)	-28,822
Nonvested ending balance (in shares)	447,932	776,596
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Awards Surrendered due to Separation	-124,263
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Awards Surrendered due to Separation, Weight Average Grant Date Fair Value	$42.90
Share-based Compensation Arrangement by Share-based Payment Awards, Equity Instruments Other than Options, Awards Granted due to Separation	45,381
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Awards Granted due to Separation, Weight Average Grant Date Fair Value	$0
Stock Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance under the Plan. (in shares)	10,000,000
Shares reserved for issuance under the plan (in shares)	2,800,000
Forfeiture rate maximum (in hundredths)	3.00%
Share based compensation expense	21,300,000	34,000,000	26,900,000
Share based compensation tax benefit	4,900,000	12,200,000	9,800,000
Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance under the Plan. (in shares)	15,600,000
Shares reserved for issuance under the plan (in shares)	1,000,000
Performance Unit Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding awards vesting period (in years)	3 years
Weighted Average Price [Abstract]
Nonvested beginning balance (in dollars per share)	$41.10
Granted (in dollars per share)	$64.75	52.34	42.39
Released to participants (in dollars per share)	$34.68
Forfeited (in dollars per share)	$48.99
Nonvested ending balance (in dollars per share)	$44.55	41.1
Fair value of shares granted	12,071,000	19,742,000	25,466,000
Unrecognized compensation cost related to our nonvested restricted stock unit awards	13,600,000
Period over which compensation cost related to nonvested restricted stock will be recognized (in years)	1 year 8 months 4 days
Restricted stock units and performance stock units activity [Roll forward]
Nonvested beginning balance (in shares)	1,652,145
Granted (in shares)	186,436
Released to participants (in shares)	-743,897
Forfeited (in shares)	-53,927
Nonvested ending balance (in shares)	872,730	1,652,145
Volatility (in hundredths)	25.48%	22.27%	27.00%
Dividend Yield (in hundredths)	2.63%	3.04%	2.86%
Risk-free Interest Rate (in hundredths)	0.69%	0.42%	0.38%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Awards Surrendered due to Separation	-265,750
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Awards Surrendered due to Separation, Weight Average Grant Date Fair Value	$47.62
Share-based Compensation Arrangement by Share-based Payment Awards, Equity Instruments Other than Options, Awards Granted due to Separation	97,723
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Awards Granted due to Separation, Weight Average Grant Date Fair Value	$0
Non-employees and Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance under the Plan. (in shares)	1,400,000
Shares reserved for issuance under the plan (in shares)	1,000,000
The maximum number of shares for which options or other awards may be granted to any employee during any year (in shares)	40,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance under the Plan. (in shares)	11,600,000
Restricted stock units and performance stock units activity [Roll forward]
Maximum allowable percentage of annual base pay withheld to purchase our common stock (in hundredths)	10.00%
Maximum allowable percentage of annual base pay from all means to purchase our common stock (in hundredths)	10.00%
Purchase price percentage of the lower of its grant date or exercise date market price (in hundredths)	85.00%
Percentage of employees participating in the Employee Stock Purchase Plan (in hundredths)	67.00%	52.00%	55.00%
Shares sold under the Employee Stock Purchase Plan (in shares)	110,592	254,960	256,490
Share price of shares sold under the Employee Stock Purchase Plan (in dollars per share)	43.85	35.97	35.97
Employee Stock Award Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock reserved for issuance under the Plan. (in shares)	900,000
Shares reserved for issuance under the plan (in shares)	49,864	63,975	42,467
Share based compensation expense	2,100,000	3,600,000	1,900,000
Description of the Plan	Under our Employee Stock Award Program, we issued, for no monetary consideration, to all eligible employees one share of our common stock when the per-share closing price of our common stock on the NYSE was for the first time at or above $13 per share.
Continuing Operations [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	$18,600,000	21,100,000	15,100,000

EMPLOYEE_BENEFIT_PLANS_Details

EMPLOYEE BENEFIT PLANS (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Rate	Rate	Rate
Defined Benefit Plan Disclosure [Line Items]
Investments Included in Other Assets, Supplemental Executive Retirement Plan	$82,400,000	$77,300,000
Deferred tax liabilities	1,557,796,000	1,280,955,000
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	1,500,000
Amounts recognized in other comprehensive income (loss) [Abstract]
Total recognized in other comprehensive income (loss)	-23,672,000	83,126,000	-11,061,000
Amounts in accumulated other comprehensive income (loss) that had not yet been recognized as components of net periodic benefit expense [Abstract]
Regulatory asset for regulated entities	-6,100,000	-383,600,000
Accumulated other comprehensive income (loss), net of tax	-99,959,000	-79,676,000	-162,802,000
Weighted average assumptions used to determine benefit obligations [Abstract]
Compensation increase rate - benefit obligation - minimum (in hundredths)	3.35%	3.35%	3.45%
Compensation increase rate, maximum (in hundredths)	3.40%	3.40%	3.50%
Weighted-average assumptions used to determine net periodic benfit costs [Abstract]
Expected long-term return on plan assets (in hundredths)	7.75%	8.25%	8.25%
Compensation increase rate, minimum (in hundredths)	3.45%	3.45%	3.20%
Compensation increase rate, maximum (in hundredths)	3.50%	3.50%	3.80%
Description of basis used to determine overall expected long-term rate of return on plan assets	We determine our overall expected long-term rate of return on plan assets, based on our review of historical returns and economic growth models. We determine our discount rates annually.B B We estimate our discount rate based upon a comparison of the expected cash flows associated with our future payments under our pension and postretirement obligations to a hypothetical bond portfolio created using high-quality bonds that closely match expected cash flows.B Bond portfolios are developed by selecting a bond for each of the next 60 years based on the maturity dates of the bonds.B B Bonds selected to be included in the portfolios are only those rated by Moodybs as AA- or better and exclude callable bonds, bonds with less than a minimum issue size, yield outliers and other filtering criteria to remove unsuitable bonds.
Assumed health care cost trend rates [Abstract]
Year that the rate reaches the ultimate trend rate	2022	2022
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase	3.20%	3.50%	3.80%
Defined Benefit Plan, Amount and Timing of Assets Expected to be Returned to Employer During Following 12 Month Period	0
One percentage point change in assumed healthcare cost trend rates [Abstract]
Effect of a one percentage point increase on total of service and interest cost	74,000
Effect of a one percentage point increase on postretirement benefit obligation	1,131,000
Effect of a one percentage point decrease on total of service and interest cost	-67,000
Effect of a one percentage point decrease on postretirement benefit obligation	-1,025,000
Target allocation for assets of the pension plan [Abstract]
U.S. large-cap equities	37.00%
Aggregate bonds	24.00%
Developed foreign large-cap equities	10.00%
Alternative investments	8.00%
Mid-cap equities	6.00%
Emerging markets equities	5.00%
Small-cap equities	4.00%
High yield bonds	3.00%
Developed foreign bonds	2.00%
Emerging market bonds	1.00%
Total	100.00%
Other Employee Benefit Plans - Thrift Plan [Abstract]
Contributions made to the Thrift Plan	9,300,000	8,400,000	7,600,000
Percent of employee contributions matched of eligible compensation (in hundredths)	100.00%
Maximum percentage of each participant's eligible compensation, subject to certain limits, matching (in hundredths)	6.00%
Profit-Sharing Plan [Abstract]
Contributions made to the Profit-Sharing Plan	4,600,000	3,400,000	4,400,000
Profit sharing contribution percentage	1.00%
Distribution Regulated Segment [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred tax liabilities	86,000,000
Defined Benefit Plan, Fair Value of Plan Assets	1,000,000,000
Change in Benefit Obligation [Roll Forward]
Benefit obligation, end of period	1,100,000,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	1,000,000,000
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	277,568,000	274,936,000	243,525,000
Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of period	361,578,000	383,979,000
Service cost	7,238,000	6,127,000	5,633,000
Interest cost	18,324,000	15,626,000	17,205,000
Plan participants' contributions	0	0
Actuarial (gain) loss	42,891,000	-32,120,000
Benefits paid	-12,101,000	-12,034,000
Other adjustments	-3,749,000	0
Benefit obligation, end of period	414,181,000	361,578,000	383,979,000
Change in Plan Assets [Roll Forward]
Fair value of plan assets, beginning of period	274,936,000	243,525,000
Actual return on plan assets	17,619,000	43,445,000
Employer contributions	0	0
Plan participants' contributions	0	0
Benefits paid	-12,101,000	-12,034,000
Other adjustments	-2,886,000	0
Fair value of assets, end of period	277,568,000	274,936,000	243,525,000
Balance at December 31	-136,613,000	-86,642,000
Current liabilities	-4,634,000	-4,645,000
Non-current liabilities	-131,979,000	-81,997,000
Balance at December 31	-136,613,000	-86,642,000
Accumulated benefit obligation for pension plans	393,300,000	343,200,000
Components of net periodic benefit cost [Abstract]
Service cost	7,238,000	6,127,000	5,633,000
Interest cost	18,324,000	15,626,000	17,205,000
Expected return on assets	-19,526,000	-19,874,000	-20,595,000
Amortization of unrecognized prior service cost	193,000	239,000	252,000
Amortization of net loss	15,078,000	19,016,000	14,403,000
Net periodic benefit cost	21,307,000	21,134,000	16,898,000
Amounts recognized in other comprehensive income (loss) [Abstract]
Net gain (loss) arising during the period	-49,293,000	51,874,000	-29,625,000
Prior service credit (cost)	193,000	239,000	252,000
Amortization of loss	15,078,000	19,016,000	14,403,000
Deferred income taxes	13,609,000	-28,452,000	5,988,000
Total recognized in other comprehensive income (loss)	-20,413,000	42,677,000	-8,982,000
Amounts in accumulated other comprehensive income (loss) that had not yet been recognized as components of net periodic benefit expense [Abstract]
Prior service credit (cost)	-94,000	-287,000
Accumulated gain (loss)	-156,985,000	-122,770,000
Accumulated other comprehensive income (loss) before regulatory assets	-157,079,000	-123,057,000
Deferred income taxes	62,832,000	49,223,000
Accumulated other comprehensive income (loss), net of tax	-94,247,000	-73,834,000
Amounts to be recognized in 2014 [Abstract]
Prior service credit (cost)	193,000	239,000	252,000
Weighted average assumptions used to determine benefit obligations [Abstract]
Discount rate (in hundredths)	4.50%	5.25%
Weighted-average assumptions used to determine net periodic benfit costs [Abstract]
Discount rate (in hundredths)	5.25%	4.25%	5.00%
Benefits to be paid in: [Abstract]
2015	13,928,000
2016	14,914,000
2017	15,887,000
2018	16,979,000
2019	18,025,000
2020 through 2024	104,652,000
Assumed health care cost trend rates [Abstract]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	3.15%	3.20%
Pension Benefits [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	165,031,000	185,587,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	165,031,000	185,587,000
Pension Benefits [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	92,307,000	69,974,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	92,307,000	69,974,000
Pension Benefits [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	20,230,000	19,375,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	20,230,000	19,375,000
Pension Benefits [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	277,568,000	274,936,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	277,568,000	274,936,000
Pension Benefits [Member] | Corporate Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Pension Benefits [Member] | Corporate Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	55,948,000	25,005,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	55,948,000	25,005,000
Pension Benefits [Member] | Corporate Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Pension Benefits [Member] | Corporate Obligations [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	55,948,000	25,005,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	55,948,000	25,005,000
Pension Benefits [Member] | Insurance Contracts and Group Annuity Contracts [Member]
Level 3 fair value measurements [Roll Forward]
Actual return on plan assets held at the reporting date	855,000
Balance at end of period	20,230,000
Pension Benefits [Member] | Other Investments [Member]
Level 3 fair value measurements [Roll Forward]
Balance at beginning of period		17,842,000
Actual return on plan assets held at the reporting date		1,533,000
Balance at end of period		19,375,000
Pension Benefits [Member] | Other Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Pension Benefits [Member] | Other Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Pension Benefits [Member] | Other Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	20,230,000	19,375,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	20,230,000	19,375,000
Pension Benefits [Member] | Other Investments [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	20,230,000	19,375,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	20,230,000	19,375,000
Pension Benefits [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	160,421,000	178,329,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	160,421,000	178,329,000
Pension Benefits [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	15,315,000	15,809,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	15,315,000	15,809,000
Pension Benefits [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Pension Benefits [Member] | Equity Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	175,736,000	194,138,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	175,736,000	194,138,000
Pension Benefits [Member] | Government Obligations [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Pension Benefits [Member] | Government Obligations [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	21,044,000	29,160,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	21,044,000	29,160,000
Pension Benefits [Member] | Government Obligations [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Pension Benefits [Member] | Government Obligations [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	21,044,000	29,160,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	21,044,000	29,160,000
Pension Benefits [Member] | Cash and Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,610,000	7,258,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	4,610,000	7,258,000
Pension Benefits [Member] | Cash and Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Pension Benefits [Member] | Cash and Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Pension Benefits [Member] | Cash and Money Market Funds [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	4,610,000	7,258,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	4,610,000	7,258,000
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum Number Of Years Of Service For Certain Employees To Be Eligible To Participate In Welfare Plans That Provide Postretirement Medical And Life Insurance Benefits	5 years
Defined Benefit Plan, Fair Value of Plan Assets	29,429,000	28,626,000	24,147,000
Change in Benefit Obligation [Roll Forward]
Benefit obligation, beginning of period	50,232,000	56,843,000
Service cost	710,000	458,000	414,000
Interest cost	2,433,000	1,164,000	1,158,000
Plan participants' contributions	1,537,000	730,000
Actuarial (gain) loss	6,822,000	-5,833,000
Benefits paid	-4,815,000	-3,130,000
Other adjustments	-256,000	0
Benefit obligation, end of period	56,663,000	50,232,000	56,843,000
Change in Plan Assets [Roll Forward]
Fair value of plan assets, beginning of period	28,626,000	24,147,000
Actual return on plan assets	1,765,000	4,481,000
Employer contributions	2,000,000	147,000
Plan participants' contributions	1,233,000	0
Benefits paid	-3,968,000	-149,000
Other adjustments	-227,000	0
Fair value of assets, end of period	29,429,000	28,626,000	24,147,000
Balance at December 31	-27,234,000	-21,606,000
Current liabilities	0	0
Non-current liabilities	-27,234,000	-21,606,000
Balance at December 31	-27,234,000	-21,606,000
Defined Benefit Plan, Contributions by Employer Including Claims Paid Directly	2,000,000
Components of net periodic benefit cost [Abstract]
Service cost	710,000	458,000	414,000
Interest cost	2,433,000	1,164,000	1,158,000
Expected return on assets	-2,163,000	-1,218,000	-891,000
Amortization of unrecognized prior service cost	-1,662,000	-1,799,000	-2,493,000
Defined Benefit Plan, Amortization of Transition Obligations (Assets)	0	49,000	169,000
Amortization of net loss	836,000	2,391,000	2,975,000
Net periodic benefit cost	154,000	1,045,000	1,332,000
Amounts recognized in other comprehensive income (loss) [Abstract]
Net gain (loss) arising during the period	-7,220,000	9,096,000	-2,423,000
Amortization of transition obligation	0	49,000	169,000
Prior service credit (cost)	-1,662,000	-1,799,000	-2,493,000
Amortization of loss	836,000	2,391,000	2,975,000
Deferred income taxes	3,218,000	-3,895,000	709,000
Total recognized in other comprehensive income (loss)	-4,828,000	5,842,000	-1,063,000
Amounts in accumulated other comprehensive income (loss) that had not yet been recognized as components of net periodic benefit expense [Abstract]
Prior service credit (cost)	6,873,000	8,535,000
Accumulated gain (loss)	-16,396,000	-10,012,000
Accumulated other comprehensive income (loss) before regulatory assets	-9,523,000	-1,477,000
Deferred income taxes	3,811,000	591,000
Accumulated other comprehensive income (loss), net of tax	-5,712,000	-886,000
Amounts to be recognized in 2014 [Abstract]
Transition obligation	0	49,000	169,000
Prior service credit (cost)	-1,662,000	-1,799,000	-2,493,000
Weighted average assumptions used to determine benefit obligations [Abstract]
Discount rate (in hundredths)	4.25%	5.00%
Weighted-average assumptions used to determine net periodic benfit costs [Abstract]
Discount rate (in hundredths)	5.00%	4.00%	5.00%
Benefits to be paid in: [Abstract]
2015	2,865,000
2016	3,011,000
2017	3,260,000
2018	3,442,000
2019	3,601,000
2020 through 2024	19,023,000
Assumed health care cost trend rates [Abstract]
Health care cost-trend rate assumed for next year - minimum (in hundredths)	4.00%	4.00%
Health care cost-trend rate assumed for next year - maximum (in hundredths)	7.75%	8.25%
Rate to which the cost-trend rate is assumed to decline (the ultimate trend rate) - minimum (in hundredths)	4.00%	5.00%
Rate to which the cost-trend rate is assumed to decline (the ultimate trend rate) - maximum (in hundredths)	5.00%	5.00%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	3.15%	3.20%
Other Postretirement Benefit Plan [Member] | Insurance Contracts and Group Annuity Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Other Postretirement Benefit Plan [Member] | Insurance Contracts and Group Annuity Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	26,186,000	25,862,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	26,186,000	25,862,000
Other Postretirement Benefit Plan [Member] | Insurance Contracts and Group Annuity Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Other Postretirement Benefit Plan [Member] | Insurance Contracts and Group Annuity Contracts [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	26,186,000	25,862,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	26,186,000	25,862,000
Other Postretirement Benefit Plan [Member] | Other Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3,243,000	2,764,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	3,243,000	2,764,000
Other Postretirement Benefit Plan [Member] | Other Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	26,186,000	25,862,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	26,186,000	25,862,000
Other Postretirement Benefit Plan [Member] | Other Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Other Postretirement Benefit Plan [Member] | Other Investments [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	29,429,000	28,626,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	29,429,000	28,626,000
Other Postretirement Benefit Plan [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,599,000	1,464,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	1,599,000	1,464,000
Other Postretirement Benefit Plan [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Other Postretirement Benefit Plan [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Other Postretirement Benefit Plan [Member] | Equity Securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,599,000	1,464,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	1,599,000	1,464,000
Other Postretirement Benefit Plan [Member] | Cash and Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,644,000	1,300,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	1,644,000	1,300,000
Other Postretirement Benefit Plan [Member] | Cash and Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Other Postretirement Benefit Plan [Member] | Cash and Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	0	0
Other Postretirement Benefit Plan [Member] | Cash and Money Market Funds [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,644,000	1,300,000
Change in Plan Assets [Roll Forward]
Fair value of assets, end of period	1,644,000	1,300,000
Pension and postretirement unrecognized losses [Member] | Distribution Regulated Segment [Member]
Amounts in accumulated other comprehensive income (loss) that had not yet been recognized as components of net periodic benefit expense [Abstract]
Regulatory asset for regulated entities		-331,100,000
Scenario, Forecast [Member] | Pension Benefits [Member]
Amounts recognized in other comprehensive income (loss) [Abstract]
Prior service credit (cost)	-94,000
Amounts to be recognized in 2014 [Abstract]
Prior service credit (cost)	-94,000
Net loss	15,981,000
Scenario, Forecast [Member] | Other Postretirement Benefit Plan [Member]
Amounts recognized in other comprehensive income (loss) [Abstract]
Prior service credit (cost)	1,662,000
Amounts to be recognized in 2014 [Abstract]
Prior service credit (cost)	1,662,000
Net loss	$1,743,000

INCOME_TAXES_Details

INCOME TAXES (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Provision for income taxes [Abstract]
State	$3,311,000	$1,812,000	$1,798,000
Federal	10,180,000	-9,531,000	41,246,000
Total current income taxes from continuing operations	13,491,000	-7,719,000	43,044,000
Deferred income taxes
Federal	152,352,000	156,818,000	134,208,000
State	-14,685,000	16,981,000	3,506,000
Total deferred income taxes from continuing operations	137,667,000	173,799,000	137,714,000
Total Provision for Income Taxes, Continuing Operations	151,158,000	166,080,000	180,758,000
Discontinued operations	7,567,000	-2,698,000	43,186,000
Total provision for income taxes	158,725,000	163,382,000	223,944,000
Reconciliation for income tax provision [Abstract]
Income from continuing operations before income taxes	819,873,000	755,170,000	858,506,000
Less: Net income attributable to noncontrolling interests	349,001,000	310,428,000	382,911,000
Income from continuing operations attributable to ONEOK before income taxes	470,872,000	444,742,000	475,595,000
Federal statutory income tax rate	35.00%	35.00%	35.00%
Provision for federal income taxes	164,805,000	155,660,000	166,458,000
State income taxes, net of federal tax benefit	14,278,000	12,102,000	7,908,000
State deferred tax rate change, net of valuation allowance	-25,653,000	0	0
Other, net	-2,272,000	-1,682,000	6,392,000
Deferred tax assets
Employee benefits and other accrued liabilities	81,905,000	78,136,000
Federal net operating loss	80,851,000	12,484,000
State net operating loss and benefits	38,429,000	38,322,000
Derivative instruments	22,511,000	22,872,000
Other	13,133,000	7,582,000
Total deferred tax assets	236,829,000	159,396,000
Carryforward expected to expire prior to utilization	-8,807,000	0
Deferred Tax Assets, Net	228,022,000	159,396,000
Deferred tax liabilities
Excess of tax over book depreciation	89,379,000	60,725,000
Investment in partnerships	1,466,456,000	1,217,605,000
Regulatory assets	1,961,000	2,625,000
Total deferred tax liabilities	1,557,796,000	1,280,955,000
Deferred Tax Liabilities, Net, before Discontinued Operations	1,329,774,000	1,121,559,000
Deferred Tax Liabilities, Parent's Basis in Discontinued Operation	-35,559,000	775,862,000
Deferred Tax Liabilities, Net	1,294,215,000	1,897,421,000
Income taxes receivable		24,700,000
Excess Tax Benefit from Share-based Compensation, Operating Activities	$54,300,000	$35,900,000

UNCONSOLIDATED_AFFILIATES_Deta

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

ONEOK_PARTNERS_Details

ONEOK PARTNERS (Details) (USD $)	12 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Related Party Transaction [Line Items]
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	$1,020,530,000	$533,824,000	$459,587,000
Aggregate amount of common units available for issuance and sale under the Equity Distribution Agreement.	650,000,000	300,000,000
Remaining Capacity of At The Market Equity Program	514,000,000
Long-term Debt, Gross	7,194,573,000	7,754,857,000
Ownership interest	37.80%	41.20%	43.40%	42.80%
Common units	19.8
Class B units	73
Partnership agreement	Cash Distributions - We receive distributions from ONEOK Partners on our common and Class B units and our 2 percent general partner interest, which includes our incentive distribution rights.B B Under ONEOK Partnersb partnership agreement, as amended, distributions are made to the partners with respect to each calendar quarter in an amount equal to 100 percent of available cash as defined in the ONEOK Partners partnership agreement (Partnership Agreement), as amended.B B Available cash generally will be distributed 98 percent to limited partners and 2 percent to the general partner.B B The general partnerbs percentage interest in quarterly distributions is increased after certain specified target levels are met during the quarter.B B Under the incentive distribution provisions, as set forth in ONEOK Partnersb partnership agreement, as amended, the 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.
Partners' Capital Account, Units, Sold in Private Placement			8
Proceeds from Issuance of Private Placement			460,000,000
Repayment on line of credit facility			295,000,000
Partnership Interest [Member]
Related Party Transaction [Line Items]
Long-term Debt, Gross	6,059,557,000	6,067,208,000
ONEOK, Inc. [Member]
Related Party Transaction [Line Items]
Revenues	53,526,000	340,743,000	352,099,000
Expenses [Abstract]
Cost of sales and fuel	10,835,000	37,963,000	33,094,000
Administrative and general expenses	330,541,000	265,448,000	246,050,000
Total expenses	341,376,000	303,411,000	279,144,000
General Partner [Member]
Related Party Transaction [Line Items]
Ownership interest	2.00%	2.00%	2.00%
Limited Partner [Member]
Related Party Transaction [Line Items]
Ownership interest	35.80%
Dividend Paid [Member]
Related Party Transaction [Line Items]
Total distributions	1,052,245,000	909,713,000	760,912,000
Distribution (in dollars per unit)	$3.01	$2.87	$2.59
Dividend Paid [Member] | General Partner [Member]
Related Party Transaction [Line Items]
General partner distributions	21,044,000	18,193,000	15,217,000
Incentive distributions	304,999,000	251,664,000	186,130,000
Distributions to general partner	326,043,000	269,857,000	201,347,000
Dividend Paid [Member] | Limited Partner [Member]
Related Party Transaction [Line Items]
Limited partner distributions to ONEOK	279,292,000	266,302,000	235,442,000
Limited partner distributions to noncontrolling interest	446,910,000	373,554,000	324,123,000
Dividend Declared [Member]
Related Party Transaction [Line Items]
Total distributions	1,105,457,000	931,236,000	817,754,000
Distribution (in dollars per unit)	$3.07	$2.89	$2.69
Dividend Declared [Member] | General Partner [Member]
Related Party Transaction [Line Items]
General partner distributions	22,109,000	18,625,000	16,355,000
Incentive distributions	326,022,000	259,466,000	210,095,000
Distributions to general partner	348,131,000	278,091,000	226,450,000
Dividend Declared [Member] | Limited Partner [Member]
Related Party Transaction [Line Items]
Limited partner distributions to ONEOK	284,860,000	268,157,000	249,600,000
Limited partner distributions to noncontrolling interest	472,466,000	384,988,000	341,704,000
Notes Payables due 2012 [Member] | Partnership Interest [Member]
Related Party Transaction [Line Items]
Long-term Debt, Gross			350,000,000
Debt Instrument, Interest Rate, Stated Percentage			5.90%
Issued under public offering [Member]
Related Party Transaction [Line Items]
Partners' Capital Account, Units, Sold in Public Offering	13.9	11.5	8
Public offering price of common units	$52.94	$49.61	$59.27
Proceeds from Sale of Interest in Partnership Unit	714,500,000	553,400,000	460,000,000
Partners' Capital Account, Contributions	15,000,000	11,600,000	19,000,000
Issued Under Equity Distribution Agreement [Member]
Related Party Transaction [Line Items]
Partners capital account units sold under equity distribution agreement	7.9	0.7
Proceeds from Sale of Interest in Partnership Unit	402,100,000	36,100,000
Additional Paid-in Capital [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	156,143,000	87,295,000	-51,100,000
Noncontrolling Interest, Increase from Sale of Parent Equity Interest			($51,100,000)

COMMITMENTS_AND_CONTINGENCIES_1

COMMITMENTS AND CONTINGENCIES (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]
Minimum percentage yield of high consequence pipeline areas	30.00%
Oneok Partners [Member]
Firm Transportation and Storage Contracts, Future Minimum Payments Due [Abstract]
2015	33.6
2016	32.1
2017	30.4
2018	29.4
2019	28.8
Thereafter	68.5
Total	222.8

SEGMENTS_Details

SEGMENTS (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Segment Reporting, Disclosure of Major Customers									ONEOK Partners had no single external customer from which it received 10 percent or more of our consolidated gross revenues.	ONEOK Partners had no single external customer from which it received 10 percent or more of our consolidated gross revenues.	ONEOK Partners had no single external customer from which it received 10 percent or more of our consolidated gross revenues.
Revenues	$2,844,768	$3,120,145	$3,066,882	$3,163,296	$3,449,559	$3,135,381	$2,768,984	$2,517,955	$12,195,091	$11,871,879	$10,184,121
Net margin	563,495	536,941	495,480	510,627	441,579	424,222	412,758	371,107	2,106,543	1,649,666	1,643,802
Operating costs									674,887	541,586	491,725
Depreciation and amortization									294,684	239,343	205,334
Gain (loss) on sale of assets									6,599	11,881	6,736
Operating Income									1,143,571	880,618	953,479
Equity earnings from investments									41,003	110,517	123,024
Investments in unconsolidated affiliates	1,132,653				1,229,838				1,132,653	1,229,838	1,221,405
Assets	15,304,560				17,741,481				15,304,560	17,741,481	15,900,973
Noncontrolling interests in consolidated subsidiaries	3,413,768				2,507,329				3,413,768	2,507,329	2,102,841
Capital expenditures									1,779,150	2,256,585	1,866,153
Unaffiliated entity [Member]
Segment Reporting Information [Line Items]
Revenues									12,141,565	11,531,136	9,832,022
Affiliated Entity [Member]
Segment Reporting Information [Line Items]
Revenues									53,526	340,743	352,099
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues									0	0	0
Corporate Elimination [Member]
Segment Reporting Information [Line Items]
Revenues									-1,668,354	-1,283,144	-908,640
Net margin									6,052	-6,618	-4,768
Operating costs									9,790	10,473	1,949
Depreciation and amortization									3,448	2,600	2,233
Gain (loss) on sale of assets									166	0	0
Operating Income									-7,020	-19,691	-8,950
Equity earnings from investments									0	0	0
Investments in unconsolidated affiliates	0				0				0	0	0
Assets	670,750				5,035,360				670,750	5,035,360	5,427,644
Noncontrolling interests in consolidated subsidiaries	3,245,846				2,502,808				3,245,846	2,502,808	2,098,089
Capital expenditures									39,215	319,162	306,095
Corporate Elimination [Member] | Unaffiliated entity [Member]
Segment Reporting Information [Line Items]
Revenues									3,426	2,606	1,970
Corporate Elimination [Member] | Affiliated Entity [Member]
Segment Reporting Information [Line Items]
Revenues									0	0	0
Corporate Elimination [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues									-1,671,780	-1,285,750	-910,610
Corporate Elimination [Member] | Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Assets	28,000				4,400,000				28,000	4,400,000	4,500,000
Capital expenditures									23,900	292,100	280,300
Natural Gas Gathering And Processing [Member]
Segment Reporting Information [Line Items]
Revenues									2,967,608	2,051,482	1,515,713
Net margin									661,885	500,627	455,170
Operating costs									257,658	193,293	164,033
Depreciation and amortization									123,847	103,962	83,031
Gain (loss) on sale of assets									219	436	2,278
Operating Income									280,599	203,808	210,384
Equity earnings from investments									-56,141	23,493	29,103
Investments in unconsolidated affiliates	254,818				333,179				254,818	333,179	333,210
Assets	4,727,201				3,949,813				4,727,201	3,949,813	3,040,198
Noncontrolling interests in consolidated subsidiaries	4,251				4,521				4,251	4,521	4,752
Capital expenditures									898,896	774,379	566,126
Natural Gas Gathering And Processing [Member] | Unaffiliated entity [Member]
Segment Reporting Information [Line Items]
Revenues									1,478,729	665,169	436,629
Natural Gas Gathering And Processing [Member] | Affiliated Entity [Member]
Segment Reporting Information [Line Items]
Revenues									41,214	238,600	253,136
Natural Gas Gathering And Processing [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues									1,447,665	1,147,713	825,948
Natural Gas Pipelines [Member]
Segment Reporting Information [Line Items]
Revenues									350,456	325,514	320,385
Net margin									328,521	285,719	286,060
Operating costs									111,037	101,182	101,899
Depreciation and amortization									43,318	43,541	45,726
Gain (loss) on sale of assets									6,786	10,602	5,390
Operating Income									180,952	151,598	143,825
Equity earnings from investments									69,818	65,046	73,220
Investments in unconsolidated affiliates	387,253				404,803				387,253	404,803	393,317
Assets	1,823,917				1,817,675				1,823,917	1,817,675	1,812,711
Noncontrolling interests in consolidated subsidiaries	0				0				0	0	0
Capital expenditures									42,991	34,699	25,383
Natural Gas Pipelines [Member] | Natural Gas Pipelines Regulated [Member]
Segment Reporting Information [Line Items]
Revenues									290,000	246,900	251,500
Net margin									242,300	217,600	220,300
Operating Income									106,500	90,500	99,300
Natural Gas Pipelines [Member] | Unaffiliated entity [Member]
Segment Reporting Information [Line Items]
Revenues									329,801	219,244	217,034
Natural Gas Pipelines [Member] | Affiliated Entity [Member]
Segment Reporting Information [Line Items]
Revenues									12,312	102,143	98,963
Natural Gas Pipelines [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues									8,343	4,127	4,388
Natural Gas Liquids [Member]
Segment Reporting Information [Line Items]
Revenues									10,545,381	10,778,027	9,256,663
Net margin									1,110,085	869,938	907,340
Operating costs									296,402	236,638	223,844
Depreciation and amortization									124,071	89,240	74,344
Gain (loss) on sale of assets									-572	843	-932
Operating Income									689,040	544,903	608,220
Equity earnings from investments									27,326	21,978	20,701
Investments in unconsolidated affiliates	490,582				491,856				490,582	491,856	494,878
Assets	8,082,692				6,938,633				8,082,692	6,938,633	5,620,420
Noncontrolling interests in consolidated subsidiaries	163,671				0				163,671	0	0
Capital expenditures									798,048	1,128,345	968,549
Natural Gas Liquids [Member] | Natural Gas Liquids Regulated [Member]
Segment Reporting Information [Line Items]
Revenues									695,900	534,800	470,600
Net margin									386,500	327,400	276,300
Operating Income									196,100	190,500	162,800
Natural Gas Liquids [Member] | Unaffiliated entity [Member]
Segment Reporting Information [Line Items]
Revenues									10,329,609	10,644,117	9,176,389
Natural Gas Liquids [Member] | Affiliated Entity [Member]
Segment Reporting Information [Line Items]
Revenues									0	0	0
Natural Gas Liquids [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenues									215,772	133,910	80,274
Natural Gas Liquids [Member] | Operating Segments [Member] | Natural Gas Liquids Regulated [Member]
Segment Reporting Information [Line Items]
Revenues									$598,100	$449,900	$397,700

QUARTERLY_FINANCIAL_DATA_UNAUD2

QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenues	$2,844,768	$3,120,145	$3,066,882	$3,163,296	$3,449,559	$3,135,381	$2,768,984	$2,517,955	$12,195,091	$11,871,879	$10,184,121
Net margin	563,495	536,941	495,480	510,627	441,579	424,222	412,758	371,107	2,106,543	1,649,666	1,643,802
Income from continuing operations	200,766	114,452	148,760	204,737	166,986	157,824	153,777	110,503	668,715	589,090	677,748
Income from discontinued operations and gain on sale, net of tax	799	-171	-8,009	1,774	17,077	-10,126	-74,282	55,202	-5,607	-12,129	52,265
Net income	201,565	114,281	140,751	206,511	184,063	147,698	79,495	165,705	663,108	576,961	743,530
Net income attributable to ONEOK	$94,544	$64,458	$61,590	$93,515	$90,737	$62,356	$919	$112,521	$314,107	$266,533	$360,619
Earnings per share total
Basic (in dollars per share)	$0.45	$0.31	$0.29	$0.45	$0.44	$0.30	$0	$0.55	$1.53	$1.35	$1.43
Diluted (in dollars per share)	$0.45	$0.31	$0.29	$0.45	$0.43	$0.30	$0	$0.54	$1.52	$1.33	$1.40