Financial Risk Management Activities - Corporate Financial Risk Management Activities - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Derivative Instruments Gain Loss [Line Items]
Amount of total gains (losses) from Brent & WTI crude oil collars, which impact Sales and other operating revenues		$ 42,000,000		$ 24,000,000
Net of pre-tax gains (losses) associated with changes in time value of Brent and WTI crude oil collars		(23,000,000)		(46,000,000)
Crude Oil
Derivative Instruments Gain Loss [Line Items]
Outstanding gross notional amount, in USD	$ 0		$ 0
Interest Rate Swaps
Derivative Instruments Gain Loss [Line Items]
Outstanding gross notional amount, in USD	650,000,000		650,000,000		$ 1,300,000,000
Amount of cash proceeds received from settled interest rate swaps	5,000,000
Change in fair value of interest rate swaps - increase/(decrease)	(9,000,000)	10,000,000	9,000,000	14,000,000
Foreign Exchange
Derivative Instruments Gain Loss [Line Items]
Outstanding gross notional amount, in USD	705,000,000		705,000,000		967,000,000
Total foreign exchange gains and (losses) reported in Other, net in Revenues and Non-Operating Income in the Statement of Consolidated Income	11,000,000	(15,000,000)	32,000,000	(7,000,000)
Gains (Losses) on foreign exchange contracts not designated as hedging instruments	(2,000,000)	13,000,000	11,000,000	71,000,000
After tax foreign currency translation adjustments gains (losses) included in Accumulated other comprehensive income (loss)	117,000,000	$ (208,000,000)	259,000,000	$ (256,000,000)
Accumulated cumulative currency translation adjustment - gain (loss)	$ (842,000,000)		$ (842,000,000)		$ (1,101,000,000)