COMMITMENTS AND CONTINGENCIES (Details) $ in Millions, $ in Millions					1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 10, 2020 defendant	Sep. 11, 2019 USD ($) plaintiff	Dec. 20, 2017 Action	Jul. 17, 2017 Action defendant	Dec. 31, 2017 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2013 USD ($)	Apr. 30, 2017 AUD ($)
Commitment And Contingencies [Line Items]
Accrued liability for legal contingencies						$ 69	$ 69
Undiscounted reserve for environmental remediation						2	2
Gulf Of Mexico Shelf Operations and Properties
Commitment And Contingencies [Line Items]
Percentage of net profits interest for funding trust account									10.00%
Gulf Of Mexico Shelf Operations and Properties | Disposed of by Sale
Commitment And Contingencies [Line Items]
Proceeds from sale of operations and properties									$ 3,750
discounted asset abandonment liabilities assumed									$ 1,500
Apollo Exploration Lawsuit
Commitment And Contingencies [Line Items]
Plaintiffs alleged damages							200	$ 1,100
Australian Operations Divestiture Dispute
Commitment And Contingencies [Line Items]
Plaintiffs alleged damages					$ 200
Gain contingency, unrecorded amount										$ 80
Canadian Operations Divestiture Dispute
Commitment And Contingencies [Line Items]
Plaintiffs alleged damages		$ 60
Number of plaintiffs | plaintiff		4
California Litigation
Commitment And Contingencies [Line Items]
Number of actions filed | Action			2	3
Number of defendants | defendant				30
Delaware Litigation
Commitment And Contingencies [Line Items]
Number of defendants | defendant	25
Castex Lawsuit
Commitment And Contingencies [Line Items]
Plaintiffs alleged damages						200
Loss contingency, estimated of possible loss amount						$ 60	60
Oklahoma Class Actions
Commitment And Contingencies [Line Items]
Plaintiffs alleged damages							$ 250