Related Party Transactions (Details) (Government Of Panama [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Government Of Panama [Member]
Related Party Transaction [Line Items]
Electricity Sales To Government	$ 144	$ 146	$ 143
Electricity Purchases Excluding Transmission Charges	65	21	25
Due To Related Parties	1	4
Receivable From Government	$ 19	$ 12

For an unclassified balance sheet, amounts due from related parties including affiliates, employees, joint ventures, officers and stockholders, immediate families thereof, and pension funds.

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-Name FASB Interpretation (FIN)

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+ Details

- Definition

Carrying amount as of the balance sheet date of obligations due all related parties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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+ Details