Name:	ceg_GainLossInvestmentIncomeNuclearDecommissioningTrustFunds
Namespace Prefix:	ceg_
Data Type:	xbrli:monetaryItemType
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Gain / loss on nuclear decommissioning trust fund investments abstract.

No definition available.

Name:	ceg_GainLossOnNuclearDecommissioningTrustFundInvestmentsAbstract
Namespace Prefix:	ceg_
Data Type:	xbrli:stringItemType
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Period Type:	duration

This item represents investment income and realized gains (losses) for the period as a result of selling marketable securities held in nuclear decommissioning trust funds classified as trading securities.

No definition available.

Name:	ceg_RealizedGainLossInvestmentIncomeNuclearDecommissioningTrustFundsNonregulatoryAccounting
Namespace Prefix:	ceg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

This item represents investment income and realized gains (losses) for the period as a result of selling marketable securities held in nuclear decommissioning trust funds and classified as trading securities. As a result of certain regulatory agreements for these nuclear decommissioning trust funds; upon completion of decommissioning activities, excess (shortfall of) funds will be refunded to (recovered from) rate payers through a regulated affiliate. Therefore, this activity is contractually eliminated within the income statement.

No definition available.

Name:	ceg_RealizedGainLossInvestmentIncomeNuclearDecommissioningTrustFundsRegulatoryAccounting
Namespace Prefix:	ceg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

This item represents the contractual elimination of nuclear decommissioning trust fund-related activity, which may include realized income (losses), unrealized income (losses), asset retirement obligation accretion, asset retirement cost amortization, investment income and related income taxes. As a result of certain regulatory agreements for these nuclear decommissioning trust funds; upon completion of decommissioning activities, excess (shortfall of) funds will be refunded to (recovered from) rate payers through a regulated affiliate. Therefore, this activity is contractually eliminated within the income statement.

No definition available.

Name:	ceg_RegulatoryOffsetNuclearDecommissioningTrustFundActivity
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Data Type:	xbrli:monetaryItemType
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Return to Provision Adjustment

No definition available.

Name:	ceg_ReturnToProvisionAdjustment
Namespace Prefix:	ceg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

This item represents unrealized gains (losses) included in earnings for the period as a result of holding marketable securities held in nuclear decommissioning trust funds and classified as trading securities.

No definition available.

Name:	ceg_UnrealizedGainLossNuclearDecommissioningTrustFundsNonregulatoryAccounting
Namespace Prefix:	ceg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

This item represents unrealized gains (losses) for the period as a result of holding marketable securities held in nuclear decommissioning trust funds and classified as trading securities. As a result of certain regulatory agreements for these nuclear decommissioning trust funds; upon completion of decommissioning activities, excess (shortfall of) funds will be refunded to (recovered from) rate payers through a regulated affiliate. Therefore, this activity is contractually eliminated within the income statement.

No definition available.

Name:	ceg_UnrealizedGainLossNuclearDecommissioningTrustFundsRegulatoryAccounting
Namespace Prefix:	ceg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(3)(d))
-URI https://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI https://asc.fasb.org/extlink&oid=126980263&loc=SL75117546-209714

Name:	us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss
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Data Type:	xbrli:monetaryItemType
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Amount of expense (reversal of expense) for net periodic benefit cost components, excluding service cost component, of defined benefit plan. Amount includes, but is not limited to, interest cost, expected (return) loss on plan asset, amortization of prior service cost (credit), amortization of (gain) loss, amortization of transition (asset) obligation, settlement (gain) loss, curtailment (gain) loss and certain termination benefits.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 45
-Paragraph 3A
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123453770&loc=SL108413299-114919