Accounts Receivable - Purchases and Sales of Accounts Receivable (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash proceeds received	$ 200			$ 400
Loss on sale of receivables	69	$ 36	$ 30
Proceeds from new transfers	6,108	6,095	2,816
Cash collections received on DPP and reinvested in the Facility	4,764	3,502	3,771
Cash collections reinvested in the Facility	10,872	9,597	6,587
Total receivables sold	423	147	824
Exelon Utility Registrants Affiliates
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables sold to Exelon's utility subsidiaries prior to the separation on February 1, 2022	4	23	$ 252
Sale of Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Derecognized receivables transferred at fair value	1,615	1,265
Cash proceeds received	1,100	900
DPP	515	365
Customer accounts receivable sold into the Facility	$ 11,274	$ 9,747

Accounts Receivable, Related Parties, Sale

No definition available.

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

- Definition

Amount of derecognized financial assets from transactions which comprise an additional transfer resulting in retention of substantially all of the exposure to the economic return throughout the term of the transaction, at the date of derecognition.

+ References

No definition available.

+ Details

Name:	ceg_TransferOfFinancialAssetsAccountedForAsSaleAdditionalTransfers
Namespace Prefix:	ceg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

No definition available.

+ Details

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

- Definition

Amount of decrease from sale of accounts receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 11
-Subparagraph (i)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919244-210447

+ Details

Name:	us-gaap_AccountsReceivableSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Cash Flows between a transferor and a transferee attributable to collections reinvested in revolving period transfers related to either a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction (including, but not limited to, servicing, recourse, and restrictions on transferor's interests in the transferred financial assets).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)(2)
-URI https://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719

+ Details

Name:	us-gaap_CashFlowsBetweenTransfereeAndTransferorProceedsFromCollectionsReinvestedInRevolvingPeriodTransfers
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Cash Flows between a transferor and a transferee attributable to newly transferred assets related to either a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction (including, but not limited to, servicing, recourse, and restrictions on transferor's interests in the transferred financial assets).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (d)(1)
-URI https://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719

+ Details

Name:	us-gaap_CashFlowsBetweenTransfereeAndTransferorProceedsFromNewTransfers
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Cash flows between transferee and transferor in payment of the transferor's beneficial interest related to a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction.

+ References

No definition available.

+ Details

Name:	us-gaap_CashFlowsBetweenTransferorAndTransfereeBeneficialInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Fair value portion of interest continued to be held by a transferor after transferring financial assets to a third party.

+ References

No definition available.

+ Details

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

- Definition

Reflects, by transferred financial asset type, the amount of sales proceeds in excess of or deficient from the sum of the carrying amounts of transferred financial assets plus transaction costs, including those transactions in which the seller/transferor has continuing involvement with the financial assets that have been transferred.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)(3)
-URI https://asc.fasb.org/extlink&oid=121570589&loc=d3e107207-111719

+ Details

Name:	us-gaap_SecuritizationFinancialAssetForWhichTransferIsAccountedAsSaleGainLossOnSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of derecognized financial assets from transactions which comprise an initial transfer and an agreement entered into in contemplation of the initial transfer resulting in retention of substantially all of the exposure to the economic return throughout the term of the transaction, at the date of derecognition.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719

+ Details

Name:	us-gaap_TransferOfFinancialAssetsAccountedForAsSalesAmountDerecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, before counterparty netting, of cash proceeds received in transfers of derecognized financial assets from transactions which comprise an initial transfer and an agreement entered into in contemplation of the initial transfer resulting in retention of substantially all of the exposure to the economic return throughout the term of the transaction.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121570589&loc=SL51823488-111719

+ Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=ceg_ExelonUtilityRegistrantsAffiliatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TransactionTypeAxis=ceg_SaleOfAccountsReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: