EMPLOYEE BENEFIT PLANS (Tables)

12 Months Ended

Dec. 31, 2014

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Assumptions Used [Table Text Block]

Actuarial Assumptions - The following table sets forth the weighted-average assumptions used by us, and ONEOK prior to 2014, to determine the 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 - other postretirement plans	5.00%	4.00%	5.00%
Expected long-term return on plan assets	7.75%	8.25%	8.25%
Compensation increase rate	3.35% - 3.50%	3.45% - 3.50%	3.20% - 3.80%

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

The following table sets forth our defined benefit pension and other postretirement benefit plans, benefit obligations and fair value of plan assets for the periods indicated:



	Pension Benefits			Other Postretirement Benefits
	Year Ended December 31, 2014
Changes in Benefit Obligation	(Thousands of dollars)
Benefit obligation, beginning of period	$	863,620		$	239,171
Service cost	11,620			3,468
Interest cost	43,791			11,605
Plan participants’ contributions	—			2,642
Actuarial loss	159,275			14,998
Benefits paid	(50,135		)	(14,196		)
Benefit obligation, end of period	1,028,171			257,688

Change in Plan Assets
Fair value of plan assets, beginning of period	840,699			147,237
Actual return on plan assets	53,907			6,912
Employer contributions	925			9,182
Plan participants’ contributions	—			2,642
Benefits paid	(50,135		)	(14,196		)
Fair value of assets, end of period	845,396			151,777
Balance at December 31	$	(182,775	)	$	(105,911	)

Current liabilities	$	(907	)	$	—
Noncurrent liabilities	(181,868		)	(105,911		)
Balance at December 31	$	(182,775	)	$	(105,911	)

Schedule of Net Benefit Costs [Table Text Block]

Components of Net Periodic Benefit Cost - The following table sets forth the components of net periodic benefit cost for our defined benefit pension and other postretirement benefit plans for the period indicated:



	Pension Benefits			Other Postretirement Benefits
	Year Ended December 31, 2014
	(Thousands of dollars)
Components of net periodic benefit cost
Service cost	$	11,620		$	3,468
Interest cost	43,791			11,605
Expected return on assets	(59,862		)	(11,393		)
Amortization of unrecognized prior service cost	549			(1,760		)
Amortization of net loss	30,200			3,969
Settlements	773			—
Net periodic benefit cost	$	27,071		$	5,889

Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]

Other Comprehensive Income (Loss) - The following table sets forth the amounts recognized in other comprehensive income (loss) related to our defined benefit pension benefits and other postretirement benefits for the period indicated:



	Pension Benefits			Other Postretirement Benefits
	Year Ended December 31, 2014
	(Thousands of dollars)
Net loss arising during the period	$	(3,543	)	$	—
Amortization of loss	518			—
Deferred income taxes	1,244			—
Total recognized in other comprehensive income (loss)	$	(1,781	)	$	—

Schedule of Net Periodic Benefit Cost Not yet Recognized [Table Text Block]

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 the period indicated:



	Pension Benefits			Other Postretirement Benefits
	December 31, 2014
	(Thousands of dollars)
Prior service credit (cost)	$	(266	)	$	4,337
Accumulated loss	(426,862		)	(64,861		)
Accumulated other comprehensive loss before regulatory assets	(427,128		)	(60,524		)
Regulatory asset for regulated entities	418,699			60,524
Accumulated other comprehensive loss after regulatory assets	(8,429		)	—
Deferred income taxes	3,255			—
Accumulated other comprehensive loss, net of tax	$	(5,174	)	$	—

Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year [Table Text Block]

The following tables set forth the amounts recognized in either accumulated comprehensive income (loss) or regulatory assets expected to be recognized as components of net periodic benefit expense in the next fiscal year:



	Pension Benefits		Other Postretirement Benefits
Amounts to be recognized in 2015	(Thousands of dollars)
Prior service credit (cost)	$	266	$	(1,760	)
Actuarial net loss	$	44,219	$	6,040

Schedule of Health Care Cost Trend Rates [Table Text Block]

Health Care Cost Trend Rates - The following table sets forth the assumed health care cost-trend rates for the periods indicated:



	2014
Health care cost-trend rate assumed for next year	4.00% - 7.75%
Rate to which the cost-trend rate is assumed to decline (the ultimate trend rate)	4.00% - 5.00%
Year that the rate reaches the ultimate trend rate	2022

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block]

Assumed health care cost-trend rates have a significant effect 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:



	One Percentage		One Percentage
	Point Increase		Point Decrease
	(Thousands of dollars)
Effect on total of service and interest cost	$	484	$	(463	)
Effect on other postretirement benefit obligation	$	6,903	$	(6,675	)

Schedule of Allocation of Plan Assets [Table Text Block]

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. To achieve this strategy, we have established a liability-driven investment strategy to change the allocations as the plan reaches certain funded status. The plan’s investments include a diverse blend of various domestic and international equities, investment-grade debt securities which mirror the cash flows of our liability, insurance contracts and alternative investments. The current target allocation for the assets of our defined benefit pension plan is as follows:



U.S. large-cap equities	37.4	%
Investment-grade bonds	30.0	%
Developed foreign large-cap equities	10.6	%
Alternative investments	7.7	%
Mid-cap equities	5.6	%
Emerging markets equities	5.0	%
Small-cap equities	3.7	%
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 other postretirement benefits plan assets by fair value category as of the measurement date:



	Pension Benefits
	December 31, 2014
Asset Category	Level 1		Level 2		Level 3		Total
	(Thousands of dollars)
Investments:
Equity Securities (a)	$	439,165	$	66,766	$	—	$	505,931
Government obligations	—		47,769		—		47,769
Corporate obligations (b)	—		153,412		—		153,412
Cash and money market funds (c)	4,152		16,341		—		20,493
Insurance contracts and group annuity contracts	—		—		59,877		59,877
Other investments (d)	—		—		57,914		57,914
Total assets	$	443,317	$	284,288	$	117,791	$	845,396

(a) - This category represents securities of the respective market sector from diverse industries.

(b) - This category represents bonds from diverse industries.

(d) - This category represents alternative investments such as hedge funds.



	Other Postretirement Benefits
	December 31, 2014
Asset Category	Level 1		Level 2		Level 3		Total
	(Thousands of dollars)
Investments:
Equity Securities (a)	$	49,553	$	12,589	$	—	$	62,142
Government obligations	—		78		—		78
Corporate obligations (b)	—		251		—		251
Cash and money market funds (c)	964		5,894		—		6,858
Insurance contracts and group annuity contracts	—		82,353		—		82,353
Other investments (d)	—		—		95		95
Total assets	$	50,517	$	101,165	$	95	$	151,777

(a) - This category represents securities of the respective market sector from diverse industries.

(b) - This category represents bonds from diverse industries.

(d) - This category represents alternative investments such as hedge funds.

Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets [Table Text Block]

The following table sets forth the reconciliation of Level 3 fair value measurements of our pension plans:



	Pension Benefits
	December 31, 2014
	Insurance Contracts			Other Investments			Total
	(Thousands of dollars)
January 1, 2014	$	63,454		$	73,590		$	137,044
Net realized and unrealized gains (losses)	3,446			(15,676		)	(12,230		)
Settlements	(7,023		)	—			(7,023		)
December 31, 2014	$	59,877		$	57,914		$	117,791

Schedule of Expected Benefit Payments [Table Text Block]

The following table sets forth the pension benefits and other postretirement benefits payments expected to be paid in 2015-2024:



	Pension Benefits		Other Postretirement Benefits
Benefits to be paid in:	(Thousands of dollars)
2015	$	51,253	$	13,611
2016	$	52,366	$	14,283
2017	$	53,622	$	15,084
2018	$	55,068	$	15,776
2019	$	56,236	$	16,398
2020 through 2024	$	301,502	$	88,596