Discontinued Operations - Additional Information (Detail) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2014 USD ($)	Dec. 31, 2014 USD ($) Lease
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Percentage of interest in WilcoHess acquired for preparation of its subsequent sale with retail business	56.00%	56.00%
Cost of acquiring additional ownership interest in WilcoHess	$ 290
Retail Business
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Cash proceeds from sale of business		$ 2,800
Gain (loss) from sale of business, pre-tax		954
Gain (loss) from sale of business, after-tax		602
Goodwill associated with divested business		115
Gain (loss) related to liquidation of LIFO inventory associated with divested business, pre-tax		275
Gain (loss) related to liquidation of LIFO inventory associated with divested business, after-tax		171
Charges for impairments, environmental matters, severance and exit costs associated with divested business, pre-tax		308
Charges for impairments, environmental matters, severance and exit costs associated with divested business, after-tax		202
Charges related to termination of lease contracts and purchase of retail gasoline stations, pre-tax		115
Charges related to termination of lease contracts and purchase of retail gasoline stations, after-tax		$ 72
Number of retail gasoline stations purchased in preparation for subsequent sale of retail business | Lease		180
Original ownership interest held in WilcoHess		44.00%
Cost of acquiring additional ownership interest in WilcoHess		$ 290
Gain (loss) from remeasurement of carrying value of original equity interest of WilcoHess to fair value, pre-tax		39
Gain (loss) from remeasurement of carrying value of original equity interest of WilcoHess to fair value, after-tax		24
Goodwill acquired during period		$ 115