SUPPLEMENTAL INFORMATION - NATURAL GAS AND CRUDE OIL PROPERTIES Costs Incurred in Natural Gas and Crude Oil Property Acquisition, Exploration and Development Activities (Unadited) (Details) MBbls in Thousands, $ in Thousands, MMBoe in Millions, MMBbls in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2019 Rate	Dec. 31, 2019 MBbls	Dec. 31, 2019 USD ($)	Dec. 31, 2019 MMBoe	Dec. 31, 2019 MMBbls	Dec. 31, 2018 Rate	Dec. 31, 2018 MBbls	Dec. 31, 2018 USD ($)	Dec. 31, 2018 MMBbls	Dec. 31, 2017 Rate	Dec. 31, 2017 MBbls	Dec. 31, 2017 USD ($)	Dec. 31, 2017 MMBoe	Dec. 31, 2017 MMBbls
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Document Period End Date		Dec. 31, 2019
Dispositions				(2,868)					(11,121)				(1,900)
Proved Developed and Undeveloped Reserve, Net (Energy), Period Increase (Decrease) | MMBoe						65.9
Proved Properties | $	[1]				$ 16,007					$ 205,253				$ 172
Unproved Properties | $	[1]				9,567					5,477				18,914
Development Costs | $	[2]				780,851					970,970				688,165
Exploratory drilling | $	[3]				32,218					36,704				80,103
Geological and geophysical | $	[3]				3,017					3,401				3,881
Total Costs Incurred | $					841,660					1,221,805				791,235
Cost Incurred to Convert PUDs to PDNP | $					308,900					438,400				463,400
Cost Incurred to Convert PUDs to PDNP, Infrastructure And Pipeline Costs | $					$ 35,300					$ 74,600				32,800
Reduction To Proved, Undeveloped And Development Costs | $														$ 24,600
Extensions, Discoveries, and Other Additions				4,285					27,946				6,005
Undeveloped Reserves Converted to Developed				0					0				0
Proved developed and undeveloped reserves percent increase or decrease | Rate			12.00%
Increase or Decrease in Proved Reserves | MMBbls											92.0
Purchases of Reserves				1,761					60,360				86,778
Revisions of Previous Estimates				112,147					55,011				52,457
Production				(49,414)					(40,160)				(31,830)
Year-over-Year Activity [Domain]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Estimated PUD conversion rate for following year | Rate			26.00%					16.00%				26.00%
Proved developed and undeveloped reserves percent increase or decrease | Rate								20.00%				33.00%
Proved Developed Reserves [Member]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Dispositions				474			0.5		4,486		4.5		20
Extensions, Discoveries, and Other Additions				4,285			4.3		7,874		7.9		2,292			2.3
Undeveloped Reserves Converted to Developed				52,169			52.2		58,294		58.3		54,648			54.6
Purchases of Reserves				441			0.4		8,758		8.8		1,305			1.3
Revisions of Previous Estimates				27,452					6,284				18,291
Production				49,414			49.4		40,160		40.2		31,830			31.8
Proved Undeveloped Reserves [Member]
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Dispositions				2,394			2.4		6,635		6.6		1,880			1.9
Proved Developed and Undeveloped Reserve, Net (Energy), Period Increase (Decrease) | MMBoe															111.5
Extensions, Discoveries, and Other Additions				0					20,072		20.1		3,713			3.7
Actual PUD conversion rate | Rate			14.00%					19.00%				23.00%
Undeveloped Reserves Converted to Developed				(52,169)					(58,294)				(54,648)
Purchases of Reserves				1,320					51,602				85,473
Revisions of Previous Estimates				84,695			74.2		48,727		71.7		34,166			89.8
Production				0					0				0
Crude Oil Equivalent (Boe)
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]
Dispositions				2,868					11,121				1,900
Extensions, Discoveries, and Other Additions				4,285					27,946				6,005
Purchases of Reserves				1,761					60,360				86,778
Revisions of Previous Estimates				112,147					55,011				52,457
Production				49,414					40,160				31,830

[1] Property acquisition costs represent costs incurred to purchase, lease or otherwise acquire a property.

[2] Development costs represent costs incurred to gain access to and prepare development well locations for drilling, drill and equip development wells, recomplete wells and provide facilities to extract, treat, gather and store crude oil, natural gas and NGLs. Of these costs incurred for the years ended December 31, 2019, 2018 and 2017, $308.9 million, $438.4 million and $463.4 million, respectively, were incurred to convert proved undeveloped reserves to proved developed reserves from the prior year end. These costs also include approximately $35.3 million, $74.6 million and $32.8 million of infrastructure and pipeline costs in 2019, 2018 and 2017 respectively. (3)

[3] Exploration costs represent costs incurred in identifying areas that may warrant examination and in examining specific areas that are considered to have prospects of containing crude oil, natural gas and NGLs. These costs include, but are not limited to, dry hole contributions and costs of drilling and equipping exploratory wells.