SUPPLEMENTAL INFORMATION ON OIL AND NATURAL GAS OPERATIONS (Unaudited) - Proved Undeveloped Reserves (Details) Boe in Thousands	12 Months Ended
Dec. 31, 2019 Boe
Proved Undeveloped Reserves (Energy)
Beginning proved undeveloped reserves at December 31, 2018	345,928
Undeveloped reserves transferred to developed	(120,920)
Revisions	(77,519)
Net purchases	4,542
Divestitures	(5,672)
Extensions and discoveries	221,500
Ending proved undeveloped reserves at December 31, 2019	367,859

Energy measure of proved undeveloped reserves of crude oil, including condensate and natural gas liquids, natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Form 20-F
-Section Item 18
-Subsection Instruction 2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61797-109447

Name:	srt_ProvedUndevelopedReserveBOE1
Namespace Prefix:	srt_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant