Derivative Instruments (Details 1) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Derivative Assets
Fair Value	$ 218	$ 237
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(123)	(133)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	95	104
Derivative Liabilities
Fair Value	(238)	(281)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	123	133
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	1	8
Net Fair Value	(114)	(140)
Commodity contracts
Derivative Assets
Fair Value	210	228
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(117)	(125)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	93	103
Derivative Liabilities
Fair Value	(124)	(131)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	117	125
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	1	3
Net Fair Value	(6)	(3)
FTRs
Derivative Assets
Fair Value	7	8
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(6)	(8)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	1	0
Derivative Liabilities
Fair Value	(6)	(13)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	6	8
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	5
Net Fair Value	0	0
NUGs
Derivative Assets
Fair Value	1	1
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	1	1
Derivative Liabilities
Fair Value	(108)	(137)
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	(108)	(137)
FES
Derivative Assets
Fair Value	214	233
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(121)	(130)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	93	103
Derivative Liabilities
Fair Value	(129)	(142)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	121	130
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	2	9
Net Fair Value	(6)	(3)
FES \| Commodity contracts
Derivative Assets
Fair Value	210	228
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(117)	(125)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	93	103
Derivative Liabilities
Fair Value	(124)	(131)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	117	125
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	1	3
Net Fair Value	(6)	(3)
FES \| FTRs
Derivative Assets
Fair Value	4	5
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	(4)	(5)
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	0	0
Net Fair Value	0	0
Derivative Liabilities
Fair Value	(5)	(11)
Amounts Not Offset in Consolidated Balance Sheet, Derivative Instruments	4	5
Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral (Received)/Pledged	1	6
Net Fair Value	$ 0	$ 0

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