Membership Interests (Equity) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance				$ (18,474)	$ (12,268)
Net loss				(3,071)	(1,168)
Effect of stock-based incentive compensation plans					2
Net effect of cash flow hedges		$ 0	$ 0	1	1
Investment by noncontrolling interests					1
Effect of debt push-down from EFH Corp. (a)	[1]			16	16
Other					(2)
Ending Balance		(21,528)	(13,418)	(21,528)	(13,418)
Membership Interests [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance				(18,439)	(12,233)
Net loss				(3,071)	(1,168)
Effect of stock-based incentive compensation plans					2
Net effect of cash flow hedges				0	0
Investment by noncontrolling interests					0
Effect of debt push-down from EFH Corp. (a)	[1]			16	16
Other					0
Ending Balance		(21,494)	(13,383)	(21,494)	(13,383)
Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance				(35)	(36)
Net loss				0	0
Effect of stock-based incentive compensation plans					0
Net effect of cash flow hedges				1	1
Investment by noncontrolling interests					0
Effect of debt push-down from EFH Corp. (a)	[1]			0	0
Other					0
Ending Balance		(34)	(35)	(34)	(35)
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance				0	1
Net loss				0	0
Effect of stock-based incentive compensation plans					0
Net effect of cash flow hedges				0	0
Investment by noncontrolling interests					1
Effect of debt push-down from EFH Corp. (a)	[1]			0	0
Other					(2)
Ending Balance		$ 0	$ 0	$ 0	$ 0

[1] Represents the interest and income tax effects of debt pushed down from EFH Corp. (Note 9).