Derivative Financial Instruments - Summary of Credit Risk Exposure (Details) $ in Millions	3 Months Ended
Mar. 31, 2025 USD ($)
Derivative [Line Items]
Cash collateral	$ 26
Letters of credit held	68
Total Exposure Before Credit Collateral
Derivative [Line Items]
Maximum exposure	1,182
Total Exposure Before Credit Collateral \| Internally rated — investment grade
Derivative [Line Items]
Maximum exposure	149
Total Exposure Before Credit Collateral \| Internally rated — non-investment grade
Derivative [Line Items]
Maximum exposure	164
Total Exposure Before Credit Collateral \| Investment grade
Derivative [Line Items]
Maximum exposure	854
Total Exposure Before Credit Collateral \| Non-investment grade
Derivative [Line Items]
Maximum exposure	15
Credit Collateral
Derivative [Line Items]
Maximum exposure	94
Credit Collateral \| Internally rated — investment grade
Derivative [Line Items]
Maximum exposure	0
Credit Collateral \| Internally rated — non-investment grade
Derivative [Line Items]
Maximum exposure	49
Credit Collateral \| Investment grade
Derivative [Line Items]
Maximum exposure	42
Credit Collateral \| Non-investment grade
Derivative [Line Items]
Maximum exposure	3
Net Exposure
Derivative [Line Items]
Maximum exposure	1,088
Net Exposure \| Investor-owned utilities, marketers, power producers
Derivative [Line Items]
Maximum exposure	901
Net Exposure \| Energy cooperatives and municipalities
Derivative [Line Items]
Maximum exposure	73
Net Exposure \| Financial Institutions
Derivative [Line Items]
Maximum exposure	62
Net Exposure \| Other
Derivative [Line Items]
Maximum exposure	52
Net Exposure \| Internally rated — investment grade
Derivative [Line Items]
Maximum exposure	149
Net Exposure \| Internally rated — non-investment grade
Derivative [Line Items]
Maximum exposure	115
Net Exposure \| Investment grade
Derivative [Line Items]
Maximum exposure	812
Net Exposure \| Non-investment grade
Derivative [Line Items]
Maximum exposure	$ 12

Letters of credit held related to credit risk

No definition available.

Name:	ceg_LettersOfCreditHeld
Namespace Prefix:	ceg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of cash collateral held for borrowed securities, for which the cash is restricted as to withdrawal or usage.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

+ Details

Name:	us-gaap_CashCollateralForBorrowedSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Maximum amount of loss due to credit risk that, based on the gross fair value of the financial instrument, the entity would incur if parties to the financial instruments that make up the concentration failed completely to perform according to the terms of the contracts and the collateral or other security, if any, for the amount due proved to be of no value to the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-21

+ Details

Name:	us-gaap_ConcentrationRiskCreditRiskFinancialInstrumentMaximumExposure
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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-5

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis=us-gaap_FairValueConcentrationOfRiskMaximumAmountOfLossMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_InternalInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InternalCreditAssessmentAxis=us-gaap_InternalNoninvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ExternalCreditRatingByGroupingAxis=us-gaap_ExternalCreditRatingInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ExternalCreditRatingByGroupingAxis=us-gaap_ExternalCreditRatingNonInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis=ceg_CreditCollateralMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueConcentrationOfRiskDisclosureItemsAxis=ceg_NetExposureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivablesByIndustryOfCounterpartyTypeAxis=ceg_InvestorOwnedUtilitiesMarketersPowerProducersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivablesByIndustryOfCounterpartyTypeAxis=ceg_EnergyCooperativesAndMunicipalitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivablesByIndustryOfCounterpartyTypeAxis=ceg_FinancialInstitutionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivablesByIndustryOfCounterpartyTypeAxis=ceg_OtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: