Supplemental Oil and Gas Disclosures (Unaudited) - Future Net Cash Flows (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Cash inflows	$ 37,204	$ 52,073
Production costs	(15,662)	(21,413)
Development costs	(6,739)	(8,055)
Income tax expense	(1,815)	(3,080)
Net cash flows	12,988	19,525
10 percent discount rate	(4,928)	(8,931)
Discounted future net cash flows	$ 8,060	10,594
Estimated future net cash flow before income tax expenses	10.00%
Total estimated future net cash flows before income tax expense discounted at 10 percent per annum	$ 9,500	13,100
Egypt [Member]
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Cash inflows	8,778	11,124
Production costs	(1,967)	(2,185)
Development costs	(1,111)	(1,515)
Income tax expense	(1,775)	(2,326)
Net cash flows	3,925	5,098
10 percent discount rate	(956)	(1,330)
Discounted future net cash flows	2,969	3,768
United States [Member]
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Cash inflows	20,067	26,610
Production costs	(8,858)	(12,178)
Development costs	(1,653)	(2,255)
Income tax expense	(32)	(63)
Net cash flows	9,524	12,114
10 percent discount rate	(5,319)	(6,876)
Discounted future net cash flows	4,205	5,238
Canada [Member]
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Cash inflows	3,625	7,345
Production costs	(2,582)	(3,841)
Development costs	(1,565)	(1,939)
Net cash flows	(522)	1,565
10 percent discount rate	549	(868)
Discounted future net cash flows	27	697
North Sea [Member]
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Cash inflows	4,734	6,994
Production costs	(2,255)	(3,209)
Development costs	(2,410)	(2,346)
Income tax expense	(8)	(691)
Net cash flows	61	748
10 percent discount rate	798	143
Discounted future net cash flows	859	891
Noncontrolling Interest [Member] | Egypt [Member]
Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Line Items]
Discounted future net cash flows	$ 1,000	$ 1,300