DEBT AND FINANCING COSTS - Additional Information (Detail) £ in Millions	1 Months Ended					3 Months Ended	12 Months Ended
	Feb. 28, 2019 GBP (£)	Nov. 30, 2018 USD ($) contract	Aug. 31, 2018 USD ($)	Mar. 31, 2018 USD ($) contract	Jan. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 GBP (£)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Mar. 01, 2019 USD ($)	Feb. 28, 2019 USD ($)	Dec. 31, 2018 GBP (£)	Aug. 31, 2017 USD ($)	Nov. 30, 2016 USD ($)
Debt Instrument [Line Items]
Loss from extinguishment of debt					$ 1,000,000		$ 94,000,000		$ 1,000,000	$ 1,000,000
Debt before unamortized discount and debt issuance costs							8,299,000,000
Line of credit outstanding							0		0
Number of credit facilities terminated | contract				2
Write off of deferred debt issuance cost				$ 4,000,000
Commercial paper program							3,500,000,000
Discount of debt amortization							3,000,000		3,000,000	3,000,000
Senior Notes
Debt Instrument [Line Items]
Debt repurchased principle amount			$ 731,000,000
Loss from extinguishment of debt			94,000,000
Extinguishment of debt amount			828,000,000
Unamortized debt issuance costs and discount			$ 5,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum potential lien on assets located in specified regions							$ 2,900,000,000
Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Percentage of liens of companies consolidated asset							15.00%						15.00%
Commercial paper
Debt Instrument [Line Items]
Period for borrowing funds							270 days	270 days
Short-term debt outstanding							$ 0		0
2015 Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Quarterly facility fees at per annum rate							0.175%	0.175%
2015 Credit Facility | Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Debt-to-capital ratio							0.60						0.60
2015 Credit Facility | Revolving Credit Facility | Base Rate
Debt Instrument [Line Items]
Margin percentage							0.075%	0.075%
2015 Credit Facility | Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Margin percentage							1.075%	1.075%
Senior Notes
Debt Instrument [Line Items]
Debt repurchased principle amount					69,000,000	$ 181,000,000				$ 181,000,000
Early repayment of senior notes					71,000,000	182,000,000
Debt premium					$ 1,000,000										$ 500,000
Loss from extinguishment of debt						$ 1,000,000
Senior Notes | Maximum
Debt Instrument [Line Items]
Debt repurchased principle amount															$ 250,000,000
Senior Notes | 7.75% notes due in 2029
Debt Instrument [Line Items]
Debt before unamortized discount and debt issuance costs														$ 300,000,000
Debt interest rate														7.75%
Unsecured Debt
Debt Instrument [Line Items]
Debt before unamortized discount and debt issuance costs							$ 8,299,000,000		8,580,000,000
Unamortized discount							44,000,000		47,000,000
Unsecured Debt | 7.75% notes due in 2029
Debt Instrument [Line Items]
Debt before unamortized discount and debt issuance costs							$ 300,000,000		300,000,000
Debt interest rate							7.75%						7.75%
Unsecured Debt | 4.375% notes due 2028
Debt Instrument [Line Items]
Debt before unamortized discount and debt issuance costs							$ 1,000,000,000		$ 0
Debt interest rate			4.375%				4.375%						4.375%
Debt tender offer, maximum aggregate purchase price			$ 1,000,000,000.0
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, number of extension options | contract				2
Credit facility, extension period for maturity				1 year
LIne of credit facility, committed amount				$ 4,000,000,000
Line of credit facility maximum borrowing capacity				$ 5,000,000,000.0
Letters of credit outstanding, amount							$ 0
Line of Credit | Revolving Credit Facility | Subsequent Event
Debt Instrument [Line Items]
Extinguishment of debt amount | £	£ 109.4
Line of Credit | Letter of Credit
Debt Instrument [Line Items]
LIne of credit facility, committed amount							2,080,000,000
Line of credit facility maximum borrowing capacity							3,000,000,000.0
Line of credit facility, commitment amount | £													£ 112.5
Line of Credit | USD Credit Facility
Debt Instrument [Line Items]
Extinguishment of debt amount							3,500,000,000
Line of Credit | GBP Credit Facility
Debt Instrument [Line Items]
Extinguishment of debt amount | £								£ 900.0
Altus Midstream LP | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit outstanding							$ 0
Line of credit facility, number of extension options | contract		2
Credit facility, extension period for maturity		1 year
Line of credit facility maximum borrowing capacity		$ 450,000,000
Debt covenant, minimum consolidated net income for three consecutive calendar months		175,000,000
Debt covenant, minimum additional capital raised		$ 250,000,000
Altus Midstream LP | Line of Credit | Revolving Credit Facility | Subsequent Event
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity												$ 800,000,000
Altus Midstream LP | Line of Credit | Revolving Credit Facility | Scenario, Forecast | Subsequent Event
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity											$ 1,500,000,000.0
Altus Midstream LP | Line of Credit | Letter of Credit | Subsequent Event
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity												100,000,000
Altus Midstream LP | Line of Credit | Swingline Loan Subfacility | Subsequent Event
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity												$ 100,000,000