Guarantees (Details) (USD $)	Jun. 30, 2011
Guarantee Obligations
Stated limit of outstanding guarantee	$ 9,600,000,000
Constellation Energy;
Guarantee Obligations
Stated limit of outstanding guarantee	9,300,000,000
Baltimore Gas and Electric Company
Guarantee Obligations
Stated limit of outstanding guarantee	300,000,000
Parent guarantor of Generation and New Energy businesses
Guarantee Obligations
Stated limit of outstanding guarantee	8,800,000,000
Estimated exposure under commercial transactions	1,500,000,000
Parent guarantor of CENG business
Guarantee Obligations
Stated limit of outstanding guarantee	500,000,000
Estimated fair value exposure under commercial transactions recorded on our consolidated balance sheets	11,100,000
BGE guarantor of Trust Preferred Securities
Guarantee Obligations
Stated limit of outstanding guarantee	$ 250,000,000

The estimated net fair value exposure for obligations which are covered by guarantees based on current market prices that is recorded on our balance sheet.

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- Definition

The estimated net exposure for obligations under commercial transactions that the parent company would have to fund based on current market prices.

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ Details

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- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 45
-Paragraph 13
-Subparagraph b

+ Details

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