Exit and Disposal Costs - Components of Costs and Expense Reversals Associated with Corporation's Restructuring Program (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Employee Severance [Member]
Restructuring Cost And Reserve [Line Items]
Employee Severance	$ 16	$ 44	$ 77	$ 235
Employee Severance [Member] | Exploration Expenses, Including Dry Holes and Lease Impairment [Member]
Restructuring Cost And Reserve [Line Items]
Employee Severance	1	1	5	16
Employee Severance [Member] | Operating Costs and Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Employee Severance	1	1	3	45
Employee Severance [Member] | Marketing Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Employee Severance	1		2	5
Employee Severance [Member] | General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Employee Severance	2	9	26	52
Employee Severance [Member] | Income from discontinued operations
Restructuring Cost And Reserve [Line Items]
Employee Severance	11	33	41	117
Facility and Other Exit Costs [Member]
Restructuring Cost And Reserve [Line Items]
Facility and Other Exit Costs	20	13	44	57
Facility and Other Exit Costs [Member] | Marketing Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Facility and Other Exit Costs	3		3
Facility and Other Exit Costs [Member] | General and Administrative Expenses [Member]
Restructuring Cost And Reserve [Line Items]
Facility and Other Exit Costs	2		(3)	9
Facility and Other Exit Costs [Member] | Income from discontinued operations
Restructuring Cost And Reserve [Line Items]
Facility and Other Exit Costs	15	13	47	48
Facility and Other Exit Costs [Member] | Depreciation, Depletion and Amortization [Member]
Restructuring Cost And Reserve [Line Items]
Facility and Other Exit Costs			$ (3)