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_
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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
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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 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
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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
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
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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
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(3)(d)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 321
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479536/321-10-50-4

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Amount of income related to nonoperating activities, classified as other.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(7)(d))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

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Period Type:	duration

Amount of income (expense) related to nonoperating activities, classified as other.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(9))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2