Consolidated Statements of Operations (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Regulated electric	$ 779	$ 747	$ 726
Regulated natural gas	125	106	108
Total operating revenue	904	853	834
Operating costs and expenses:
Cost of fuel, energy and capacity	361	292	263
Natural gas purchased for resale	76	56	62
Operating and maintenance expense	158	197	190
Depreciation and amortization	105	123	108
Property and other taxes	26	25	23
Merger-related expenses	0	20	0
Total operating costs and expenses	726	713	646
Operating Income (Loss)	178	140	188
Other income (expense):
Interest expense	(61)	(61)	(65)
Allowance for Funds Used During Construction, Capitalized Interest	2	1	2
Allowance for equity funds	3	2	3
Other, net	12	6	(4)
Total other income (expense)	(44)	(52)	(64)
Income before income tax expense	134	88	124
Income Tax Expense (Benefit)	47	33	40
Net income	$ 87	$ 55	$ 84