Asset Impairments (Details 1) $ in Millions		3 Months Ended		12 Months Ended
	Jul. 19, 2016 MW	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of assets		$ 9,218			$ 42
Impairment			$ 800	$ 800
Contract Termination
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restructuring charges			58
CES
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of assets		9,218	647
Impairment of assets					34
Impairment				$ 800
CES | Income Approach Valuation Technique | Goodwill
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate (percent)				9.50%
Terminal value of EBITDA				7.0
Regulated Distribution
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of assets					8
Impairment				$ 0
FES
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of assets		8,082			$ 33
Impairment			23	$ 23
FES | CES
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of assets		$ 8,082	$ 517
Bay Shore Unit 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Plant capacity (in MW's) | MW	136
Sammis Power Plant Units 1-4
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Plant capacity (in MW's) | MW	720