Taxes (Details Textuals) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2018	Dec. 31, 2014
Income Taxes (Textuals) [Abstract]
Increase in income tax provision		$ 1,200
Effective tax rate absent the impact from the Tax Act		35.90%
Effective income tax rate (percent)		(108.00%)	33.10%	35.30%
Impairment	$ 800		$ 800
Goodwill, Impairment Loss, Non-deductible Portion			433
Unrecognized tax benefits		$ 80	$ 84	$ 34		$ 34
Unrecognized tax benefits that would impact future tax rates		24
Unrecognized tax benefits, portion expected to be resolved in the next fiscal year		2
Unrecognized tax benefits that would impact effective tax rate		0
Federal
Income Taxes (Textuals) [Abstract]
Operating loss carryforwards, not subject to expiration		39
Federal | Begin To Expire in 2031
Income Taxes (Textuals) [Abstract]
Pre-tax net operating loss carryforwards for state and local income tax purposes		4,300
Operating loss carryforwards, subject to expiration		908
State and Local
Income Taxes (Textuals) [Abstract]
Operating loss carryforwards valuation allowance		246
Pre-tax net operating loss carryforwards for state and local income tax purposes		10,500
Operating loss carryforwards, subject to expiration		496
Pre-tax net operating loss carryforwards expected to utilized		1,800
Operating loss carryforwards expected to utilized, net of tax		81
FES
Income Taxes (Textuals) [Abstract]
Increase in income tax provision		$ 1,100
Effective tax rate absent the impact from the Tax Act		36.80%
Effective income tax rate (percent)		(14.10%)	35.40%	44.20%
Impairment	$ 23		$ 23
Unrecognized tax benefits		$ 0	$ 0	$ 8		$ 3
FES | Federal | Begin To Expire in 2031
Income Taxes (Textuals) [Abstract]
Pre-tax net operating loss carryforwards for state and local income tax purposes		2,000
Operating loss carryforwards, subject to expiration		429
FES | State and Local
Income Taxes (Textuals) [Abstract]
Operating loss carryforwards valuation allowance		151
Pre-tax net operating loss carryforwards for state and local income tax purposes		3,700
Operating loss carryforwards, subject to expiration		154
Pre-tax net operating loss carryforwards expected to utilized		2
Forecast
Income Taxes (Textuals) [Abstract]
Decrease in Unrecognized Tax Benefits is Reasonably Possible					$ 45
Regulated Distribution
Income Taxes (Textuals) [Abstract]
Excess deferred taxes		$ 2,300