SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Revenues from Contracts with Customers and Non-customers (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Schedule Of Significant Accounting Policies [Line Items]
Production revenues from customers	$ 0		$ 0	$ 0
Oil and gas, excluding purchased
Schedule Of Significant Accounting Policies [Line Items]
Production revenues from customers	1,407	$ 715	2,732	1,903
Production revenues from non-customers	107	(18)	213	30
Total production revenues	$ 1,514	$ 697	$ 2,945	$ 1,933