SUPPLEMENTAL CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Tables)

6 Months Ended

Jun. 30, 2018

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

Condensed Consolidating Statements of Income



	Three Months Ended June 30, 2018
(Unaudited)	Parent Issuer & Guarantor			Subsidiary Issuer & Guarantor			Guarantor Subsidiary			Combined Non-Guarantor Subsidiaries			Consolidating Entries			Total
	(Millions of dollars)
Revenues
Commodity sales	$	—		$	—		$	—		$	2,675.3		$	—		$	2,675.3
Services	—			—			—			285.8			(0.5		)	285.3
Total revenues	—			—			—			2,961.1			(0.5		)	2,960.6
Cost of sales and fuel (exclusive of items shown separately below)	—			—			—			2,175.8			—			2,175.8
Operating expenses	2.0			—			—			335.0			(0.5		)	336.5
Gain on sale of assets	—			—			—			(0.1		)	—			(0.1		)
Operating income	(2.0		)	—			—			450.4			—			448.4
Equity in net earnings from investments	400.8			403.2			403.2			27.5			(1,198.1		)	36.6
Other income (expense), net	6.6			77.5			77.5			(8.4		)	(155.0		)	(1.8		)
Interest expense, net	(40.3		)	(77.5		)	(77.5		)	(73.2		)	155.0			(113.5		)
Income before income taxes	365.1			403.2			403.2			396.3			(1,198.1		)	369.7
Income taxes	(84.0		)	—			—			(3.5		)	—			(87.5		)
Net income	281.1			403.2			403.2			392.8			(1,198.1		)	282.2
Less: Net income attributable to noncontrolling interests	—			—			—			1.1			—			1.1
Net income attributable to ONEOK	281.1			403.2			403.2			391.7			(1,198.1		)	281.1
Less: Preferred stock dividends	0.3			—			—			—			—			0.3
Net income available to common shareholders	$	280.8		$	403.2		$	403.2		$	391.7		$	(1,198.1	)	$	280.8



	Three Months Ended June 30, 2017
(Unaudited)	Parent Issuer & Guarantor			Subsidiary Issuer & Guarantor			Guarantor Subsidiary			Combined Non-Guarantor Subsidiaries			Consolidating Entries			Total
	(Millions of dollars)
Revenues
Commodity sales	$	—		$	—		$	—		$	2,161.0		$	—		$	2,161.0
Services	—			—			—			565.8			(1.0		)	564.8
Total revenues	—			—			—			2,726.8			(1.0		)	2,725.8
Cost of sales and fuel (exclusive of items shown separately below)	—			—			—			2,091.0			—			2,091.0
Operating expenses	17.7			—			6.2			293.0			(1.0		)	315.9
Gain on sale of assets	—			—			—			(0.6		)	—			(0.6		)
Operating income	(17.7		)	—			(6.2		)	343.4			—			319.5
Equity in net earnings from investments	275.2			278.5			284.7			23.8			(822.8		)	39.4
Other income (expense), net	(20.2		)	94.9			94.9			(0.4		)	(189.8		)	(20.6		)
Interest expense, net	(24.5		)	(94.9		)	(94.9		)	(94.0		)	189.8			(118.5		)
Income before income taxes	212.8			278.5			278.5			272.8			(822.8		)	219.8
Income taxes	(37.7		)	—			—			(6.1		)	—			(43.8		)
Net income	175.1			278.5			278.5			266.7			(822.8		)	176.0
Less: Net income attributable to noncontrolling interests	103.4			—			—			0.9			—			104.3
Net income attributable to ONEOK	71.7			278.5			278.5			265.8			(822.8		)	71.7
Less: Preferred stock dividends	0.2			—			—			—			—			0.2
Net income available to common shareholders	$	71.5		$	278.5		$	278.5		$	265.8		$	(822.8	)	$	71.5



	Six Months Ended June 30, 2018
(Unaudited)	Parent Issuer & Guarantor			Subsidiary Issuer & Guarantor			Guarantor Subsidiary			Combined Non-Guarantor Subsidiaries			Consolidating Entries			Total
	(Millions of dollars)
Revenues
Commodity sales	$	—		$	—		$	—		$	5,495.3		$	—		$	5,495.3
Services	—			—			—			568.3			(1.0		)	567.3
Total revenues	—			—			—			6,063.6			(1.0		)	6,062.6
Cost of sales and fuel (exclusive of items shown separately below)	—			—			—			4,543.8			—			4,543.8
Operating expenses	1.3			—			—			650.6			(1.0		)	650.9
Gain on sale of assets	—			—			—			(0.2		)	—			(0.2		)
Operating income	(1.3		)	—			—			869.4			—			868.1
Equity in net earnings from investments	769.3			774.1			774.1			56.1			(2,296.8		)	76.8
Other income (expense), net	13.8			154.6			154.6			(18.0		)	(309.2		)	(4.2		)
Interest expense, net	(80.1		)	(154.6		)	(154.6		)	(149.1		)	309.2			(229.2		)
Income before income taxes	701.7			774.1			774.1			758.4			(2,296.8		)	711.5
Income taxes	(156.1		)	—			—			(7.2		)	—			(163.3		)
Net income	545.6			774.1			774.1			751.2			(2,296.8		)	548.2
Less: Net income attributable to noncontrolling interests	—			—			—			2.6			—			2.6
Net income attributable to ONEOK	545.6			774.1			774.1			748.6			(2,296.8		)	545.6
Less: Preferred stock dividends	0.6			—			—			—			—			0.6
Net income available to common shareholders	$	545.0		$	774.1		$	774.1		$	748.6		$	(2,296.8	)	$	545.0



	Six Months Ended June 30, 2017
(Unaudited)	Parent Issuer & Guarantor			Subsidiary Issuer & Guarantor			Guarantor Subsidiary			Combined Non-Guarantor Subsidiaries			Consolidating Entries			Total
	(Millions of dollars)
Revenues
Commodity sales	$	—		$	—		$	—		$	4,377.7		$	—		$	4,377.7
Services	—			—			—			1,098.7			(1.0		)	1,097.7
Total revenues	—			—			—			5,476.4			(1.0		)	5,475.4
Cost of sales and fuel (exclusive of items shown separately below)	—			—			—			4,234.9			—			4,234.9
Operating expenses	24.7			—			6.2			574.6			(1.0		)	604.5
Gain on sale of assets	—			—			—			(0.6		)	—			(0.6		)
Operating income	(24.7		)	—			(6.2		)	667.5			—			636.6
Equity in net earnings from investments	544.0			547.6			553.8			44.5			(1,611.0		)	78.9
Other income (expense), net	(19.6		)	186.1			186.1			—			(372.2		)	(19.6		)
Interest expense, net	(50.3		)	(186.1		)	(186.1		)	(184.6		)	372.2			(234.9		)
Income before income taxes	449.4			547.6			547.6			527.4			(1,611.0		)	461.0
Income taxes	(89.0		)	—			—			(9.8		)	—			(98.8		)
Net income	360.4			547.6			547.6			517.6			(1,611.0		)	362.2
Less: Net income attributable to noncontrolling interests	201.3			—			—			1.8			—			203.1
Net income attributable to ONEOK	159.1			547.6			547.6			515.8			(1,611.0		)	159.1
Less: Preferred stock dividends	0.2			—			—			—			—			0.2
Net income available to common shareholders	$	158.9		$	547.6		$	547.6		$	515.8		$	(1,611.0	)	$	158.9

Condensed Consolidating Statements of Comprehensive Income



	Three Months Ended June 30, 2018
(Unaudited)	Parent Issuer & Guarantor		Subsidiary Issuer & Guarantor			Guarantor Subsidiary			Combined Non-Guarantor Subsidiaries			Consolidating Entries			Total
	(Millions of dollars)
Net income	$	281.1	$	403.2		$	403.2		$	392.8		$	(1,198.1	)	$	282.2
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	15.5		(46.4		)	(46.4		)	(35.8		)	92.8			(20.3		)
Realized (gains) losses on derivatives in net income, net of tax	1.0		14.6			10.2			6.9			(20.5		)	12.2
Change in pension and postretirement benefit plan liability, net of tax	3.2		—			—			—			—			3.2
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	—		1.2			1.2			1.0			(2.4		)	1.0
Total other comprehensive income (loss), net of tax	19.7		(30.6		)	(35.0		)	(27.9		)	69.9			(3.9		)
Comprehensive income	300.8		372.6			368.2			364.9			(1,128.2		)	278.3
Less: Comprehensive income attributable to noncontrolling interests	—		—			—			1.1			—			1.1
Comprehensive income attributable to ONEOK	$	300.8	$	372.6		$	368.2		$	363.8		$	(1,128.2	)	$	277.2



	Three Months Ended June 30, 2017
(Unaudited)	Parent Issuer & Guarantor			Subsidiary Issuer & Guarantor			Guarantor Subsidiary			Combined Non-Guarantor Subsidiaries			Consolidating Entries			Total
	(Millions of dollars)
Net income	$	175.1		$	278.5		$	278.5		$	266.7		$	(822.8	)	$	176.0
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	(0.3		)	(5.7		)	9.0			9.8			(17.9		)	(5.1		)
Realized (gains) losses on derivatives in net income, net of tax	0.5			11.1			6.8			5.1			(13.6		)	9.9
Change in pension and postretirement benefit plan liability, net of tax	2.1			—			—			—			—			2.1
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	—			(1.6		)	(1.6		)	(1.4		)	3.2			(1.4		)
Total other comprehensive income (loss), net of tax	2.3			3.8			14.2			13.5			(28.3		)	5.5
Comprehensive income	177.4			282.3			292.7			280.2			(851.1		)	181.5
Less: Comprehensive income attributable to noncontrolling interests	105.6			—			—			0.9			—			106.5
Comprehensive income attributable to ONEOK	$	71.8		$	282.3		$	292.7		$	279.3		$	(851.1	)	$	75.0



	Six Months Ended June 30, 2018
(Unaudited)	Parent Issuer & Guarantor		Subsidiary Issuer & Guarantor			Guarantor Subsidiary			Combined Non-Guarantor Subsidiaries			Consolidating Entries			Total
	(Millions of dollars)
Net income	$	545.6	$	774.1		$	774.1		$	751.2		$	(2,296.8	)	$	548.2
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	33.9		(25.5		)	(25.5		)	(19.6		)	51.0			14.3
Realized (gains) losses on derivatives in net income, net of tax	1.9		28.9			21.8			15.1			(43.6		)	24.1
Change in pension and postretirement benefit plan liability, net of tax	6.4		(0.6		)	—			—			—			5.8
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	—		4.9			4.9			3.8			(9.8		)	3.8
Total other comprehensive income (loss), net of tax	42.2		7.7			1.2			(0.7		)	(2.4		)	48.0
Comprehensive income	587.8		781.8			775.3			750.5			(2,299.2		)	596.2
Less: Comprehensive income attributable to noncontrolling interests	—		—			—			2.6			—			2.6
Comprehensive income attributable to ONEOK	$	587.8	$	781.8		$	775.3		$	747.9		$	(2,299.2	)	$	593.6



	Six Months Ended June 30, 2017
(Unaudited)	Parent Issuer & Guarantor			Subsidiary Issuer & Guarantor			Guarantor Subsidiary			Combined Non-Guarantor Subsidiaries			Consolidating Entries			Total
	(Millions of dollars)
Net income	$	360.4		$	547.6		$	547.6		$	517.6		$	(1,611.0	)	$	362.2
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax	(0.3		)	23.1			36.3			32.8			(72.6		)	19.3
Realized (gains) losses on derivatives in net income, net of tax	1.0			30.9			22.1			17.4			(44.2		)	27.2
Change in pension and postretirement benefit plan liability, net of tax	4.1			—			—			—			—			4.1
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax	—			(1.2		)	(1.2		)	(1.0		)	2.4			(1.0		)
Total other comprehensive income (loss), net of tax	4.8			52.8			57.2			49.2			(114.4		)	49.6
Comprehensive income	365.2			600.4			604.8			566.8			(1,725.4		)	411.8
Less: Comprehensive income attributable to noncontrolling interests	232.4			—			—			1.8			—			234.2
Comprehensive income attributable to ONEOK	$	132.8		$	600.4		$	604.8		$	565.0		$	(1,725.4	)	$	177.6

Condensed Consolidating Balance Sheets



	June 30, 2018
(Unaudited)	Parent Issuer & Guarantor		Subsidiary Issuer & Guarantor		Guarantor Subsidiary		Combined Non-Guarantor Subsidiaries		Consolidating Entries			Total
Assets	(Millions of dollars)
Current assets
Cash and cash equivalents	$	15.3	$	—	$	—	$	—	$	—		$	15.3
Accounts receivable, net	—		—		—		934.7		—			934.7
Natural gas and natural gas liquids in storage	—		—		—		285.8		—			285.8
Other current assets	11.9		—		—		186.0		—			197.9
Total current assets	27.2		—		—		1,406.5		—			1,433.7
Property, plant and equipment
Property, plant and equipment	137.2		—		—		16,226.5		—			16,363.7
Accumulated depreciation and amortization	89.2		—		—		2,970.6		—			3,059.8
Net property, plant and equipment	48.0		—		—		13,255.9		—			13,303.9
Investments and other assets
Investments	5,872.9		3,243.0		8,795.0		795.4		(17,719.3		)	987.0
Intercompany notes receivable	3,679.2		8,140.9		2,588.9		—		(14,409.0		)	—
Other assets	233.0		—		—		1,006.9		(50.8		)	1,189.1
Total investments and other assets	9,785.1		11,383.9		11,383.9		1,802.3		(32,179.1		)	2,176.1
Total assets	$	9,860.3	$	11,383.9	$	11,383.9	$	16,464.7	$	(32,179.1	)	$	16,913.7
Liabilities and equity
Current liabilities
Current maturities of long-term debt	$	—	$	925.0	$	—	$	7.7	$	—		$	932.7
Short-term borrowings	156.0		—		—		—		—			156.0
Accounts payable	6.2		—		—		1,021.3		—			1,027.5
Other current liabilities	71.2		85.0		—		299.7		—			455.9
Total current liabilities	233.4		1,010.0		—		1,328.7		—			2,572.1

Intercompany debt	—		—		8,140.9		6,268.1		(14,409.0		)	—

Long-term debt, excluding current maturities	2,727.0		4,339.2		—		25.0		—			7,091.2

Deferred credits and other liabilities	235.0		—		—		227.7		(50.8		)	411.9

Commitments and contingencies

Equity
Equity excluding noncontrolling interests in consolidated subsidiaries	6,664.9		6,034.7		3,243.0		8,441.6		(17,719.3		)	6,664.9
Noncontrolling interests in consolidated subsidiaries	—		—		—		173.6		—			173.6
Total equity	6,664.9		6,034.7		3,243.0		8,615.2		(17,719.3		)	6,838.5
Total liabilities and equity	$	9,860.3	$	11,383.9	$	11,383.9	$	16,464.7	$	(32,179.1	)	$	16,913.7



	December 31, 2017
(Unaudited)	Parent Issuer & Guarantor		Subsidiary Issuer & Guarantor		Guarantor Subsidiary		Combined Non-Guarantor Subsidiaries		Consolidating Entries				Total
Assets	(Millions of dollars)
Current assets
Cash and cash equivalents	$	37.2	$	—	$	—	$	—	$	—			$	37.2
Accounts receivable, net	—		—		—		1,203.0		—				1,203.0
Materials and supplies	—		—		—		90.3		—				90.3
Natural gas and natural gas liquids in storage	—		—		—		342.3		—				342.3
Other current assets	9.8		1.3		—		80.6		—				91.7
Total current assets	47.0		1.3		—		1,716.2		—			—	1,764.5
Property, plant and equipment
Property, plant and equipment	128.3		—		—		15,431.3		—				15,559.6
Accumulated depreciation and amortization	86.4		—		—		2,775.1		—				2,861.5
Net property, plant and equipment	41.9		—		—		12,656.2		—				12,698.1
Investments and other assets
Investments	5,752.1		3,133.7		8,058.4		803.0		(16,744.0		)		1,003.2
Intercompany notes receivable	2,926.9		8,627.8		3,703.1		—		(15,257.8		)		—
Other assets	416.9		0.2		—		1,007.4		(44.4		)		1,380.1
Total investments and other assets	9,095.9		11,761.7		11,761.5		1,810.4		(32,046.2		)		2,383.3
Total assets	$	9,184.8	$	11,763.0	$	11,761.5	$	16,182.8	$	(32,046.2	)		$	16,845.9
Liabilities and equity
Current liabilities
Current maturities of long-term debt	$	—	$	425.0	$	—	$	7.7	$	—			$	432.7
Short-term borrowings	614.7		—		—		—		—				614.7
Accounts payable	12.0		—		—		1,128.6		—				1,140.6
Other current liabilities	65.9		85.0		—		328.4		—				479.3
Total current liabilities	692.6		510.0		—		1,464.7		—				2,667.3

Intercompany debt	—		—		8,627.8		6,630.0		(15,257.8		)		—

Long-term debt, excluding current maturities	2,726.4		5,336.4		—		28.8		—				8,091.6

Deferred credits and other liabilities	237.9		—		—		208.1		(44.4		)		401.6

Commitments and contingencies

Equity
Equity excluding noncontrolling interests in consolidated subsidiaries	5,527.9		5,916.6		3,133.7		7,693.7		(16,744.0		)		5,527.9
Noncontrolling interests in consolidated subsidiaries	—		—		—		157.5		—				157.5
Total equity	5,527.9		5,916.6		3,133.7		7,851.2		(16,744.0		)		5,685.4
Total liabilities and equity	$	9,184.8	$	11,763.0	$	11,761.5	$	16,182.8	$	(32,046.2	)		$	16,845.9

Condensed Consolidating Statements of Cash Flows



	Six Months Ended June 30, 2018
(Unaudited)	Parent Issuer & Guarantor			Subsidiary Issuer & Guarantor			Guarantor Subsidiary				Combined Non-Guarantor Subsidiaries			Consolidating Entries			Total
	(Millions of dollars)
Operating activities
Cash provided by operating activities	$	669.2		$	673.9		$	32.4			$	959.5		$	(1,332.0	)	$	1,003.0
Investing activities
Capital expenditures	(10.1		)	—			—				(605.3		)	—			(615.4		)
Contributions to unconsolidated affiliates	—			—			—				(0.3		)	—			(0.3		)
Other investing activities	—			—			6.4				7.9			—			14.3
Cash provided by (used in) investing activities	(10.1		)	—			6.4				(597.7		)	—			(601.4		)
Financing activities
Dividends paid	(643.5		)	(666.0		)	(666.0		)		—			1,332.0			(643.5		)
Distributions to noncontrolling interests	—			—			—				(3.0		)	—			(3.0		)
Intercompany borrowings (advances), net	(748.0		)	492.1			627.2				(371.3		)	—			—
Borrowing (repayment) of short-term borrowings, net	(458.7		)	—			—				—			—			(458.7		)
Repayment of long-term debt	—			(500.0		)	—				(3.8		)	—			(503.8		)
Issuance of common stock	1,186.7			—			—				—			—			1,186.7
Other, net	(17.5		)	—			—				16.3			—			(1.2		)
Cash used in financing activities	(681.0		)	(673.9		)	(38.8		)	—	(361.8		)	1,332.0			(423.5		)
Change in cash and cash equivalents	(21.9		)	—			—				—			—			(21.9		)
Cash and cash equivalents at beginning of period	37.2			—			—				—			—			37.2
Cash and cash equivalents at end of period	$	15.3		$	—		$	—			$	—		$	—		$	15.3



	Six Months Ended June 30, 2017
(Unaudited)	Parent Issuer & Guarantor			Subsidiary Issuer & Guarantor			Guarantor Subsidiary			Combined Non-Guarantor Subsidiaries			Consolidating Entries			Total
	(Millions of dollars)
Operating activities
Cash provided by operating activities	$	355.0		$	675.2		$	28.2		$	645.5		$	(1,061.0	)	$	642.9
Investing activities
Capital expenditures	(0.1		)	—			—			(195.1		)	—			(195.2		)
Other investing activities	—			—			6.7			4.8			—			11.5
Cash provided by (used in) investing activities	(0.1		)	—			6.7			(190.3		)	—			(183.7		)
Financing activities
Dividends paid	(259.8		)	(666.0		)	(666.0		)	—			1,332.0			(259.8		)
Distributions to noncontrolling interests	—			—			—			(2.5		)	(271.0		)	(273.5		)
Intercompany borrowings (advances), net	(27.1		)	(166.1		)	642.1			(448.9		)	—			—
Borrowing (repayment) of short-term borrowings, net	—			164.1			—			—			—			164.1
Repayment of long-term debt	(0.1		)	—			—			(3.8		)	—			(3.9		)
Issuance of common stock	10.8			—			—			—			—			10.8
Other, net	(6.2		)	(7.2		)	—			—			—			(13.4		)
Cash used in financing activities	(282.4		)	(675.2		)	(23.9		)	(455.2		)	1,061.0			(375.7		)
Change in cash and cash equivalents	72.5			—			11.0			—			—			83.5
Cash and cash equivalents at beginning of period	248.5			—			0.4			—			—			248.9
Cash and cash equivalents at end of period	$	321.0		$	—		$	11.4		$	—		$	—		$	332.4