The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 9
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 45
-Paragraph 13
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Litigation and Other Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended					6 Months Ended
	Jun. 30, 2011 cubicFeet gal	May 01, 2007	Jun. 30, 2011 Equity Company Obligations [Member]	Jun. 30, 2011 Guarantees, Notes, Loans And Performance [Member]	Jun. 27, 2007 Expropriation of Assets [Member]	Jun. 30, 2011 Compensatory Damages [Member]	Jun. 30, 2011 Punitive Damages [Member]
Total guarantees	$ 9,618		$ 6,433	$ 9,618
Percentage ownership interest in Cerro Negro Project		41.67%			41.67%
Net book investment in Cerro Negro Project	750
Accidental gasoline leak (gallons)	26,000
Litigation court verdict						$ 497	$ 1,000