Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 146	$ 143
Income Taxes Receivable, Noncurrent	50
Pepco Holdings LLC [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	56	56
Atlantic City Electric Company [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 16	$ 16

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(17))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(5)(c))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

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