The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

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

Asset Retirement Obligations (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2017	Dec. 31, 2016
FES \| Beaver Valley, Davis-Besse and Perry Power Plants
Asset Retirement Obligations [Line Items]
Asset retirement obligation			$ 800	$ 713
FES \| Beaver Valley Unit 2
Asset Retirement Obligations [Line Items]
ARO transferred	$ 73
FES \| Perry Power Plant Unit 1
Asset Retirement Obligations [Line Items]
ARO transferred		$ 28
NG \| Beaver Valley Unit 2
Asset Retirement Obligations [Line Items]
ARO transferred	$ 49