Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Income Tax Contingency [Line Items]
Unrecognized tax benefits	$ 138	$ 148
Income taxes receivable, noncurrent	50	50
Pepco Holdings LLC
Income Tax Contingency [Line Items]
Unrecognized tax benefits	56	59
Atlantic City Electric Company
Income Tax Contingency [Line Items]
Unrecognized tax benefits	$ 16	$ 17

Carrying amount due after one year of the balance sheet date (or one operating cycle, if longer) from tax authorities as of the balance sheet date representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(17))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

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