Revenue (Tables)

12 Months Ended

Dec. 31, 2018

Revenue from Contract with Customer [Abstract]

Revenue Recognition [Table Text Block]

The following table presents the impact to the Consolidated Statements of Operations as a result of adopting ASC Topic 606.

	Year Ended December 31, 2018
	As Reported			ASC Topic 606 Adjustments		As Adjusted(1)
REVENUES	(in millions, except per share amounts)
Oil and condensate, gas and NGL sales	$	1,871.3		$	55.0	$	1,926.3
Other revenues	12.5			—		12.5
Purchased oil and gas sales	48.8			—		48.8
Total Revenues	1,932.6			55.0		1,987.6
OPERATING EXPENSES
Purchased oil and gas expense	51.0			—		51.0
Lease operating expense	263.1			—		263.1
Transportation and processing costs	117.6			55.0		172.6
Gathering and other expense	15.5			—		15.5
General and administrative	221.7			—		221.7
Production and property taxes	130.8			—		130.8
Depreciation, depletion and amortization	857.1			—		857.1
Exploration expenses	0.3			—		0.3
Impairment	1,560.9			—		1,560.9
Total Operating Expenses	3,218.0			55.0		3,273.0
Net gain (loss) from asset sales, inclusive of restructuring costs	25.0			—		25.0
OPERATING INCOME (LOSS)	(1,260.4		)	—		(1,260.4		)
Realized and unrealized gains (losses) on derivative contracts (Note 7)	90.4			—		90.4
Interest and other income (expense)	(9.6		)	—		(9.6		)
Interest expense	(149.4		)	—		(149.4		)
INCOME (LOSS) BEFORE INCOME TAXES	(1,329.0		)	—		(1,329.0		)
Income tax (provision) benefit	317.4			—		317.4
NET INCOME (LOSS)	$	(1,011.6	)	$	—	$	(1,011.6	)
Earnings (loss) per common share
Basic	$	(4.25	)	$	—	$	(4.25	)
Diluted	$	(4.25	)	$	—	$	(4.25	)
Weighted-average common shares outstanding
Used in basic calculation	237.9			—		237.9
Used in diluted calculation	237.9			—		237.9

Revenue Recognition 606 [Table Text Block]

The following table presents the impact to the Consolidated Statements of Operations as a result of adopting ASC Topic 606.

	Year Ended December 31, 2018
	As Reported			ASC Topic 606 Adjustments		As Adjusted(1)
REVENUES	(in millions, except per share amounts)
Oil and condensate, gas and NGL sales	$	1,871.3		$	55.0	$	1,926.3
Other revenues	12.5			—		12.5
Purchased oil and gas sales	48.8			—		48.8
Total Revenues	1,932.6			55.0		1,987.6
OPERATING EXPENSES
Purchased oil and gas expense	51.0			—		51.0
Lease operating expense	263.1			—		263.1
Transportation and processing costs	117.6			55.0		172.6
Gathering and other expense	15.5			—		15.5
General and administrative	221.7			—		221.7
Production and property taxes	130.8			—		130.8
Depreciation, depletion and amortization	857.1			—		857.1
Exploration expenses	0.3			—		0.3
Impairment	1,560.9			—		1,560.9
Total Operating Expenses	3,218.0			55.0		3,273.0
Net gain (loss) from asset sales, inclusive of restructuring costs	25.0			—		25.0
OPERATING INCOME (LOSS)	(1,260.4		)	—		(1,260.4		)
Realized and unrealized gains (losses) on derivative contracts (Note 7)	90.4			—		90.4
Interest and other income (expense)	(9.6		)	—		(9.6		)
Interest expense	(149.4		)	—		(149.4		)
INCOME (LOSS) BEFORE INCOME TAXES	(1,329.0		)	—		(1,329.0		)
Income tax (provision) benefit	317.4			—		317.4
NET INCOME (LOSS)	$	(1,011.6	)	$	—	$	(1,011.6	)
Earnings (loss) per common share
Basic	$	(4.25	)	$	—	$	(4.25	)
Diluted	$	(4.25	)	$	—	$	(4.25	)
Weighted-average common shares outstanding
Used in basic calculation	237.9			—		237.9
Used in diluted calculation	237.9			—		237.9

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⁽¹⁾  This column excludes the impact of adopting ASC Topic 606 and is consistent with the presentation prior to January 1, 2018.

Disaggregation of Revenue [Table Text Block]

The following tables present our revenues that are disaggregated by revenue source and by geographic area. Transportation and processing costs in the following tables are not all of the transportation and processing costs that the Company incurs, only the expenses that are netted against revenues pursuant to ASC Topic 606.

	Oil and condensate sales			Gas sales		NGL sales		Transportation and processing costs included in revenue			Oil and condensate, gas and NGL sales, as reported
	(in millions)
	Year Ended December 31, 2018
Northern Region
Williston Basin	$	707.0		$	45.3	$	56.5	$	(43.1	)	$	765.7
Uinta Basin	25.3			25.0		4.8		—			55.1
Other Northern(1)	4.9			2.0		—		—			6.9
Southern Region
Permian Basin	684.4			17.3		49.5		(11.9		)	739.3
Haynesville/Cotton Valley	1.0			303.1		—		—			304.1
Other Southern	(0.2		)	0.4		—		—			0.2
Total oil and condensate, gas and NGL sales	$	1,422.4		$	393.1	$	110.8	$	(55.0	)	$	1,871.3
	Year Ended December 31, 2017(2)
Northern Region
Williston Basin	$	586.5		$	42.3	$	51.5	$	—		$	680.3
Pinedale	18.0			154.8		31.8		—			204.6
Uinta Basin	29.6			50.0		5.9		—			85.5
Other Northern	4.9			16.6		0.3		—			21.8
Southern Region
Permian Basin	298.8			15.5		22.0		—			336.3
Haynesville/Cotton Valley	1.2			214.4		0.4		—			216.0
Other Southern	0.4			0.4		—		—			0.8
Total oil and condensate, gas and NGL sales	$	939.4		$	494.0	$	111.9	$	—		$	1,545.3
	Year Ended December 31, 2016(2)
Northern Region
Williston Basin	$	541.6		$	33.1	$	22.7	$	—		$	597.4
Pinedale	25.8			194.1		40.6		—			260.5
Uinta Basin	28.0			52.5		6.4		—			86.9
Other Northern	5.0			18.7		0.3		—			24.0
Southern Region
Permian Basin	166.1			11.6		12.9		—			190.6
Haynesville/Cotton Valley	1.1			106.6		0.4		—			108.1
Other Southern	1.5			0.5		0.2		—			2.2
Total oil and condensate, gas and NGL sales	$	769.1		$	417.1	$	83.5	$	—		$	1,269.7

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⁽¹⁾  For the year ended December 31, 2018, immaterial amounts of revenue associated with adjustments in Pinedale have been included in Other Northern.

⁽²⁾  Prior period amounts have not been adjusted under the modified retrospective method.