Financial Risk Management Activities - Corporate Financial Risk Management Activities - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 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		$ 17,000,000
Interest Rate Swaps
Derivative Instruments Gain Loss [Line Items]
Outstanding gross notional amount, in USD	$ 1,300,000,000		$ 1,300,000,000
Unrealized change in fair value of interest rate swaps - increase/(decrease)	14,000,000	10,000,000
Foreign Exchange
Derivative Instruments Gain Loss [Line Items]
Outstanding gross notional amount, in USD	837,000,000		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	6,000,000	15,000,000
Gain (Loss) on foreign exchange contracts not designated as hedging instruments	(20,000,000)	98,000,000
After tax foreign currency translation adjustments included in Accumulated other comprehensive income (loss)	169,000,000	$ (120,000,000)
Accumulated cumulative currency translation adjustment	$ (932,000,000)		$ (1,101,000,000)