SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019	Dec. 31, 2018
Schedule Of Significant Accounting Policies [Line Items]
Impairments of oil and gas properties	$ 9,000,000		$ 10,000,000	$ 249,000,000	$ 10,000,000
Oil and gas production revenues	1,438,000,000		1,976,000,000	4,690,000,000	5,645,000,000
Cost of oil and gas purchased	66,000,000		92,000,000	230,000,000	260,000,000
Receivables from contracts with customer, net	919,000,000			919,000,000			$ 1,000,000,000.0
Fixed operating lease expenses	53,000,000			167,000,000
Other noncurrent liabilities	(491,000,000)			(491,000,000)			(219,000,000)
Long-term debt	8,393,000,000			8,393,000,000			$ 8,093,000,000
Variable lease payment	3,000,000			44,000,000
Accounting Standards Update 2016-02
Schedule Of Significant Accounting Policies [Line Items]
Other noncurrent liabilities						$ 39,000,000
Long-term debt						$ 39,000,000
Oil and Gas, Purchased
Schedule Of Significant Accounting Policies [Line Items]
Oil and gas production revenues	30,000,000		124,000,000	71,000,000	326,000,000
Cost of oil and gas purchased	23,000,000		109,000,000	60,000,000	308,000,000
Oil and Gas Properties, Proved
Schedule Of Significant Accounting Policies [Line Items]
Impairments of oil and gas properties	0		0	86,000,000	0
Assets held-for-sale, fair value		$ 379,000,000
Oil and Gas Properties, Unproved
Schedule Of Significant Accounting Policies [Line Items]
Impairments of oil and gas properties	12,000,000		49,000,000	223,000,000	86,000,000
Assets held under Finance Leases
Schedule Of Significant Accounting Policies [Line Items]
Depreciation	2,000,000			6,000,000
Interest costs	$ 1,000,000			$ 2,000,000
Altus Midstream Company
Schedule Of Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners	21.00%			21.00%
Minimum
Schedule Of Significant Accounting Policies [Line Items]
Percentage of voting interests acquired	50.00%			50.00%
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Percentage of voting interests acquired	50.00%			50.00%
North Sea | Oil and Gas Properties, Unproved
Schedule Of Significant Accounting Policies [Line Items]
Impairments of oil and gas properties			$ 10,000,000		$ 10,000,000
Altus Midstream
Schedule Of Significant Accounting Policies [Line Items]
Assets held-for-sale, fair value	$ 18,000,000			$ 18,000,000
Disposed of by Sale | Oklahoma and Texas
Schedule Of Significant Accounting Policies [Line Items]
Impairments of oil and gas properties		240,000,000
Disposed of by Sale | Oklahoma and Texas | Oil and Gas Properties, Proved
Schedule Of Significant Accounting Policies [Line Items]
Impairments of oil and gas properties		86,000,000
Disposed of by Sale | Oklahoma and Texas | Oil and Gas Properties, Unproved
Schedule Of Significant Accounting Policies [Line Items]
Impairments of oil and gas properties				$ 149,000,000
Disposed of by Sale | Oklahoma and Texas | Other Working Capital
Schedule Of Significant Accounting Policies [Line Items]
Impairments of oil and gas properties		$ 5,000,000