Revenue (Tables)

12 Months Ended

Dec. 31, 2019

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue [Table Text Block]

	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, 2019
Northern Region
Williston Basin	$	420.8		$	33.1	$	19.4	$	(34.4	)	$	438.9
Other Northern	1.1			0.4		0.1		—			1.6
Southern Region
Permian Basin	710.6			12.8		37.8		(20.5		)	740.7
Other Southern(1)	0.1			6.1		—		—			6.2
Total oil and condensate, gas and NGL sales	$	1,132.6		$	52.4	$	57.3	$	(54.9	)	$	1,187.4
	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	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

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⁽¹⁾  For the year ended December 31, 2019, $5.9 million of revenues associated with Haynesville/Cotton Valley have been included in Other Southern.

⁽²⁾ 

Prior period amounts have not been adjusted under the modified retrospective method under ASC Topic 606.