Condensed Statements Of Consolidated Income (Loss) - USD ($) $ in Millions	3 Months Ended			5 Months Ended	9 Months Ended
	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Operating revenues	$ 1,737		$ 1,807		$ 4,265	$ 4,731
Fuel, purchased power costs and delivery fees	(831)		(868)		(2,090)	(2,256)
Net gain (loss) from commodity hedging and trading activities	103		75		226	(118)
Operating costs	(189)		(204)		(598)	(660)
Depreciation and amortization	(200)		(327)		(634)	(983)
Selling, general and administrative expenses	(174)		(163)		(495)	(527)
Impairment of goodwill (Note 3)	(700)	$ (700)	0		(1,400)	0
Impairment of long-lived assets (Note 5)	(1,295)		(9)		(1,971)	(30)
Other income (Note 15)	4		5		15	11
Other deductions (Note 15)	(25)		(5)		(86)	(8)
Interest expense and related charges (Note 6)	(326)		(325)		(967)	(1,434)
Reorganization items (Note 7)	(39)		(45)	$ (468)	(152)	(468)
Loss before income taxes	(1,935)		(59)		(3,887)	(1,742)
Income tax benefit (Note 4)	417		21		816	574
Net loss	(1,518)		(38)		(3,071)	(1,168)
Other comprehensive income, net of tax effects – cash flow hedges derivative value net loss related to hedged transactions recognized during the period (net of tax benefit of $— in all periods)	0		0		1	1
Comprehensive loss	$ (1,518)		$ (38)		$ (3,070)	$ (1,167)