Exit and Disposal Costs - Components and Changes in Restructuring Accruals (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013
Restructuring Cost and Reserve [Line Items]
Provision	$ 44
Balance at ending of period	218	218
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period
Provision		235
Payments		(30)
Balance at ending of period	205	205
Facility and Other Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period
Provision		57
Payments		(44)
Balance at ending of period	13	13
Continuing operations [Member] | Exploration and Production [Member]
Restructuring Cost and Reserve [Line Items]
Balance at ending of period	61	61
Continuing operations [Member] | Corporate and Other [Member]
Restructuring Cost and Reserve [Line Items]
Balance at ending of period	26	26
Continuing operations [Member] | Employee Severance [Member] | Exploration and Production [Member]
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period
Provision		86
Payments		(25)
Balance at ending of period	61	61
Continuing operations [Member] | Employee Severance [Member] | Corporate and Other [Member]
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period
Provision		27
Payments		(1)
Balance at ending of period	26	26
Continuing operations [Member] | Facility and Other Exit Costs [Member] | Exploration and Production [Member]
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period
Provision		9
Payments		(9)
Discontinued operations-Downstream businesses [Member]
Restructuring Cost and Reserve [Line Items]
Provision	33	122
Balance at ending of period	131	131
Discontinued operations-Downstream businesses [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period
Provision		122
Payments		(4)
Balance at ending of period	118	118
Discontinued operations-Downstream businesses [Member] | Facility and Other Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance at beginning of period
Provision		48
Payments		(35)
Balance at ending of period	$ 13	$ 13