Accounting for Suspended Exploratory Wells (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Well Project		Dec. 31, 2012 Project		Dec. 31, 2011 Project
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized exploratory well costs that have been capitalized for period greater than one year	$ 2,604		$ 2,180		$ 1,877
Number of projects with exploratory well costs that have been capitalized for a period greater than one year	51	[1]	46	[1]	47	[1]
Expected period for decision on the recognition of proved reserves	3 years
Exploratory well costs capitalized for a period greater than one year	2,604		2,180		1,877
Total number of exploratory wells that have been capitalized for period greater than one year	191
Drilling Activity [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized exploratory well costs that have been capitalized for period greater than one year	1,733
Number of projects with exploratory well costs that have been capitalized for a period greater than one year	22
Exploratory well costs capitalized for a period greater than one year	1,733
No Drilling Activity [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized exploratory well costs that have been capitalized for period greater than one year	871
Number of projects with exploratory well costs that have been capitalized for a period greater than one year	29
Exploratory well costs capitalized for a period greater than one year	871
Undergoing Front End Engineering and Design with Final Investment Decision Expected [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized exploratory well costs that have been capitalized for period greater than one year	382
Number of projects with exploratory well costs that have been capitalized for a period greater than one year	6
Undergoing front-end engineering and design with final investment decision expected in three years	3 years
Exploratory well costs capitalized for a period greater than one year	382
Development Concept Under Review by Government [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized exploratory well costs that have been capitalized for period greater than one year	47
Number of projects with exploratory well costs that have been capitalized for a period greater than one year	2
Exploratory well costs capitalized for a period greater than one year	47
Reviewing Development Alternatives [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized exploratory well costs that have been capitalized for period greater than one year	384
Number of projects with exploratory well costs that have been capitalized for a period greater than one year	9
Exploratory well costs capitalized for a period greater than one year	384
Miscellaneous Activities for Projects with Smaller Amounts Suspended [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Number of projects with exploratory well costs that have been capitalized for a period greater than one year	12
Capitalized exploratory well costs that are approved and construction in progress	$ 58

[1] Certain projects have multiple wells or fields or both.