Financial Risk Management Activities - Gross & Net Fair Values of Financial Risk Management Derivative Instruments (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Assets - Gross fair value of derivative contracts	$ 157	$ 69
Liabilities - Gross fair value of derivative contracts	(1)	(55)
Gross amount offset in the Consolidate Balance Sheet, Assets	0	(13)
Gross amount offset in the Consolidate Balance Sheet, Liabilities	0	13
Derivative Asset	157	56
Derivative Liability	(1)	(42)
Derivative Contracts Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Assets - Gross fair value of derivative contracts	157	69
Liabilities - Gross fair value of derivative contracts	0	(54)
Derivative Contracts Designated as Hedging Instruments: \| Commodity Options / Collars
Derivatives, Fair Value [Line Items]
Assets - Gross fair value of derivative contracts	155	64
Liabilities - Gross fair value of derivative contracts	0	0
Derivative Contracts Designated as Hedging Instruments: \| Crude Oil Swaps
Derivatives, Fair Value [Line Items]
Assets - Gross fair value of derivative contracts		0
Liabilities - Gross fair value of derivative contracts		(54)
Derivative Contracts Designated as Hedging Instruments: \| Interest Rate Swaps
Derivatives, Fair Value [Line Items]
Assets - Gross fair value of derivative contracts	2	5
Liabilities - Gross fair value of derivative contracts	0	0
Derivative Contracts Not Designated as Hedging Instruments:
Derivatives, Fair Value [Line Items]
Assets - Gross fair value of derivative contracts	0	0
Liabilities - Gross fair value of derivative contracts	(1)	(1)
Derivative Contracts Not Designated as Hedging Instruments: \| Foreign Exchange Forwards
Derivatives, Fair Value [Line Items]
Assets - Gross fair value of derivative contracts	0	0
Liabilities - Gross fair value of derivative contracts	$ (1)	$ (1)

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