NATURE OF BUSINESS, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND OTHER - Supplemental Cash Flow Information (Details) shares in Thousands, $ in Millions		12 Months Ended
		Dec. 31, 2019 USD ($) tranche shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)	Jul. 31, 2019 shares
Supplemental Cash Flow Information
Interest paid, net of capitalized amounts		$ 425	$ 433	$ 393
Value of common stock at issuance	[1]		$ 101
Elk Hills transaction
Supplemental Cash Flow Information
Warrant outstanding (in shares) | shares		400
Common stock issued		$ 3
Common stock shares issued (in shares) | shares			2,850
Value of common stock at issuance			$ 51
Colony Capital, Inc.
Supplemental Cash Flow Information
Number of tranches | tranche		2
Warrant outstanding (in shares) | shares		200			1,250

[1] Includes 2.85 million shares of common stock (valued at $51 million at issuance) issued to Chevron in connection with our acquisition of Chevron's working interest in the Elk Hills unit and 2.3 million shares of common stock (valued at $50 million at issuance) issued to an Ares-led investor group. See Part II, Item 8 – Financial Statements and Supplementary Data, Note 4 Acquisitions and Divestitures and Part II, Item 8 – Financial Statements and Supplementary Data, Note 5 Joint Ventures for more information.