Financial Instruments Derivatives Guarantees (Details Textual) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Additional Financial Instruments Derivatives Guarantees (Textuals) [Abstract]
Maximum Loss recognized in revenue on energy commodity derivatives not designated as hedging	$ (1)	$ (1)
Percentage of long term debt publicly traded	95.00%		100.00%
Net losses of cash flow hedge to be reclassified into earnings within next year	$ (2)
Expected future net cash flow for current derivatives	12 months

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 45
-Subparagraph b(2)
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6887037&loc=d3e80748-113994

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