Early Nuclear Plant Retirements Early Nuclear Plant Retirements Narrative (Details)	Dec. 31, 2017
Exelon Generation Co L L C [Member] \| Nuclear Plant [Member]
Property, Plant and Equipment [Line Items]
Ownership interest	42.59%

The proportionate share of interest (percent) in a jointly owned utility plant.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 10.C)
-URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033

Name:	us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant