Consolidated Statements of Operations (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]
Operating revenue	$ 595	$ 536	$ 1,012	$ 906
Operating costs and expenses:
Cost of fuel, energy and capacity	284	209	487	351
Operating and maintenance expense	87	104	169	203
Depreciation and amortization	69	65	135	130
Property and other taxes	10	10	21	20
Merger related expenses	0	9	0	9
Total operating costs and expenses	450	397	812	713
Operating income	145	139	200	193
Other income (expense):
Interest expense, net of allowance for debt funds	(52)	(53)	(103)	(106)
Allowance for equity funds	0	2	0	4
Other, net	4	3	10	8
Total other income (expense)	(48)	(48)	(93)	(94)
Income before income tax expense	97	91	107	99
Income tax expense	35	32	39	35
Net income	$ 62	$ 59	$ 68	$ 64