Financial Risk Management Activities - Corporate Financial Risk Management Activities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest Rate Swaps | Designated as Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Outstanding gross notional amount	$ 100,000,000	$ 100,000,000
Unrealized change in fair value of interest rate swaps - increase (decrease) in derivative liability	4,000,000	(3,000,000)	$ 1,000,000
Foreign Exchange
Derivative Instruments, Gain (Loss) [Line Items]
Outstanding gross notional amount	163,000,000	90,000,000
Total foreign exchange gains and (losses) reported in Other, net in Revenues and Non-Operating Income in the Statement of Consolidated Income	(6,000,000)	3,000,000	(5,000,000)
Gain (Loss) on foreign exchange contracts not designated as hedging instruments	2,000,000	(2,000,000)	(2,000,000)
Derivative Contracts Designated as Hedging Instruments | Commodity Option | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax deferred income (losses) in Accumulated other comprehensive income (loss) to be reclassified into earnings during the next 12 months	4,000,000
Derivative Contracts Designated as Hedging Instruments | Crude Oil
Derivative Instruments, Gain (Loss) [Line Items]
Increased (decreased) sales and other operating revenue	$ 547,000,000	$ 1,000,000	(161,000,000)
Derivative Contracts Not Designated as Hedging Instruments | Crude Oil
Derivative Instruments, Gain (Loss) [Line Items]
Crude oil price hedging contracts decreased sales and other operating revenues by this amount, pre-tax			$ 22,000,000