Organization and Basis of Presentation (Details 4)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Annual Composite Depreciation Rate
Annual Composite Depreciation Rate (percent)	2.40%	2.50%	2.50%
FES
Annual Composite Depreciation Rate
Annual Composite Depreciation Rate (percent)	4.40%	3.30%	3.20%

Composite depreciation rate for public utility plants in service.

No definition available.

Name:	us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDisclosureOfCompositeDepreciationRateForPlantsInService
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration