The amount remitted to variable interest entities for rate stabilization bonds.

Name:	ceg_AmountRemittedToVariableInterestEntitiesOnRateStabilizationBonds
Namespace Prefix:	ceg
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of variable interest entities consolidated in the reporting entity's consolidated financial statements.

+ Details

Name:	ceg_NumberOfVariableInterestEntities
Namespace Prefix:	ceg
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of variable interest entities (VIEs) not consolidated.

+ Details

Name:	ceg_NumberOfVariableInterestEntitiesNotConsolidated
Namespace Prefix:	ceg
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of ownership interest in certain nonconsolidated VIEs where none of the equity holders consolidate these VIEs.

+ Details

Name:	ceg_OwnershipPercentageOfNonconsolidatedVariableInterestEntities
Namespace Prefix:	ceg
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amount of the consolidated Variable Interest Entity's current assets included in the reporting entity's statement of financial position.

+ Details

Name:	ceg_VariableInterestEntityConsolidatedCarryingAmountAssetsCurrent
Namespace Prefix:	ceg
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's noncurrent assets included in the reporting entity's statement of financial position.

+ Details

Name:	ceg_VariableInterestEntityConsolidatedCarryingAmountAssetsNoncurrent
Namespace Prefix:	ceg
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's current portion of liabilities included in the reporting entity's statement of financial position.

+ Details

Name:	ceg_VariableInterestEntityConsolidatedCarryingAmountLiabilitiesCurrent
Namespace Prefix:	ceg
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's noncurrent portion of liabilities included in the reporting entity's statement of financial position.

+ Details

Name:	ceg_VariableInterestEntityConsolidatedCarryingAmountLiabilitiesNoncurrent
Namespace Prefix:	ceg
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

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

+ Details

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

- Definition

The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=6970148&loc=d3e5710-111685

+ Details

Name:	us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssets
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_VariableInterestEntityConsolidatedCarryingAmountAssetsAndLiabilitiesAbstract
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amount of the consolidated Variable Interest Entity's liabilities included in the reporting entity's statement of financial position.

+ References

+ Details

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

- Definition

The amount of financial or other support the reporting entity has provided (explicitly or implicitly) to the Variable Interest Entity (VIE) that it was not previously contractually required to provide or that the reporting entity intends to provide, including, for example, situations in which the reporting entity assisted the VIE in obtaining another type of support.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 5A

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6970148&loc=SL6759159-111685

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4/FIN46(R)-8

-Paragraph C4

-Subparagraph c

-Clause 1

-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.

+ Details

Name:	us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

Name:	us-gaap_VariableInterestEntityLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Variable Interest Entities (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended		3 Months Ended		9 Months Ended				3 Months Ended	9 Months Ended
	Sep. 30, 2011 Consolidated Variable Interest Entities. Entity	Dec. 31, 2010 Consolidated Variable Interest Entities. Entity	Sep. 30, 2011 RSB BondCo. LLC	Sep. 30, 2010 RSB BondCo. LLC	Sep. 30, 2011 RSB BondCo. LLC	Sep. 30, 2010 RSB BondCo. LLC	Sep. 30, 2011 Unconsolidated Variable Interest Entities. Entity	Dec. 31, 2010 Unconsolidated Variable Interest Entities. Entity	Sep. 30, 2011 Retail gas supply contract Parental guarantee	Sep. 30, 2011 Retail gas supply contract Parental guarantee	Sep. 30, 2011 Letter of credit
Variable Interest Entity
Number of consolidated variable interest entities	4	3
Number of Variable Interest Entities not consolidated by equity holders							6	6
Ownership percentage, nonconsolidated variable interest entity (as a percent)	100.00%
Remittance by BGE of payments received from customers for rate stabilization			$ 26.5	$ 26.7	$ 65.0	$ 68.7
Parental guarantee provided											150
Obligations under gas supply agreement									75	75
Carrying amount of consolidated assets and liabilities of VIE
Current assets	544.1	516.6
Noncurrent assets	222.6	57.7
Total Assets	766.7	574.3
Current liabilities	370.9	345.5
Noncurrent liabilities	550.6	399.0
Total Liabilities	$ 921.5	$ 744.5