Derivatives - Narrative (Details) $ in Millions		1 Months Ended	3 Months Ended
	May 04, 2020 USD ($) Bbls_per_day $ / bbl	May 04, 2020 USD ($) Bbls_per_day $ / bbl	Mar. 31, 2020 USD ($) Bbls_per_day	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) on commodity derivatives			$ 202	$ (91)
Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) on commodity derivatives			171	(113)
Net gain (loss) on settlements, net			31	22
Interest Rate
Derivative Instruments, Gain (Loss) [Line Items]
Deferred loss related to interest rate swaps			20
Operating Segments | United States E&P
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss) on commodity derivatives			31	$ 22
Cash Flow Hedging | Interest Rate
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount			$ 350		$ 320
Notes Due 2022 [Member] | Subsequent Event | Interest Rate
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	$ 150	$ 150
Notes Due 2025 [Member] | Subsequent Event | Interest Rate
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	$ 150	$ 150
Not Designated as Hedges | Three-Way Collars - Crude Oil 2020 Q2 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day			80,000
Not Designated as Hedges | Subsequent Event | Three-Way Collars - Crude Oil 2020 Q2 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day	0	0
Not Designated as Hedges | Subsequent Event | Two-Way Collars - Crude Oil 2020 Q2 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day	40,000	40,000
Not Designated as Hedges | Subsequent Event | Two-Way Collars - Crude Oil 2020, Q2 Average Price [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Underlying, Derivative Volume | $ / bbl		33.79
Not Designated as Hedges | Subsequent Event | Two-Way Collars - Crude Oil 2020 Q2, Ceiling [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Underlying, Derivative Volume | $ / bbl	40.31	40.31
Not Designated as Hedges | Subsequent Event | Two-Way Collars - Crude Oil 2020 Q2, Floor [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Underlying, Derivative Volume | $ / bbl	32.89	32.89