Derivative Instruments (Details 1) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivative Assets
Fair Value	$ 37	$ 218
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(20)	(123)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	17	95
Derivative Liabilities
Fair Value	(107)	(238)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	20	123
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	3	1
Net Fair Value	(84)	(114)
Commodity contracts
Derivative Assets
Fair Value	33	210
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(19)	(117)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	14	93
Derivative Liabilities
Fair Value	(27)	(124)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	19	117
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	3	1
Net Fair Value	(5)	(6)
FTRs
Derivative Assets
Fair Value	4	7
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(1)	(6)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	3	1
Derivative Liabilities
Fair Value	(1)	(6)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	1	6
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	0	0
NUGs
Derivative Assets
Fair Value		1
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments		0
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged		0
Net Fair Value		1
Derivative Liabilities
Fair Value	(79)	(108)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	0	0
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	(79)	(108)
FES
Derivative Assets
Fair Value	34	214
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(20)	(121)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	14	93
Derivative Liabilities
Fair Value	(24)	(129)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	20	121
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	2
Net Fair Value	(4)	(6)
FES \| Commodity contracts
Derivative Assets
Fair Value	33	210
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(19)	(117)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	14	93
Derivative Liabilities
Fair Value	(23)	(124)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	19	117
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	1
Net Fair Value	(4)	(6)
FES \| FTRs
Derivative Assets
Fair Value	1	4
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(1)	(4)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	0	0
Derivative Liabilities
Fair Value	(1)	(5)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	1	4
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	1
Net Fair Value	$ 0	$ 0

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Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

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