Financial Risk Management Activities - Corporate Financial Risk Management Activities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commodity
Derivative Instruments Gain Loss [Line Items]
Crude oil price hedging contracts increased (decreased) E&P sales and other operating revenues by this amount, pre-tax	$ 126,000,000	$ 193,000,000	$ 39,000,000
Other operating revenue, losses associated with changes in time value of crude oil collars	(48,000,000)
Interest Rate Swaps
Derivative Instruments Gain Loss [Line Items]
Outstanding gross notional amount, in USD	1,300,000,000	1,300,000,000
Amount of cash proceeds received from settled interest rate swaps	41,000,000
Change in the fair value of interest rate swaps - increase/(decrease)	4,000,000	1,000,000	(35,000,000)
Foreign Exchange
Derivative Instruments Gain Loss [Line Items]
Outstanding gross notional amount, in USD	967,000,000	1,189,000,000
Total foreign exchange gains and (losses) reported in Other, net in Revenues and Non-Operating Income in the Statement of Consolidated Income	(21,000,000)	(43,000,000)	(54,000,000)
Gain (Loss) on foreign exchange contracts not designated as hedging instruments	98,000,000	117,000,000	(39,000,000)
After tax foreign currency translation adjustments included in Accumulated other comprehensive income (loss)	(344,000,000)	(756,000,000)	$ (164,000,000)
Accumulated cumulative currency translation adjustment	$ (1,101,000,000)	$ (757,000,000)