STATEMENTS OF INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues [Abstract]
Operating revenue	$ 1,870	$ 1,826	$ 1,933
Operating expenses
Electric fuel and purchased power	835	875	1,043
Operating and maintenance expenses	275	285	283
Demand side management program expenses	16	17	18
Depreciation and amortization	295	230	210
Taxes (other than income taxes)	90	72	68
Total operating expenses	1,511	1,479	1,622
Operating income	359	347	311
Other income (expense), net	(2)	2	(3)
Allowance for funds used during construction — equity	33	27	19
Interest charges and financing costs
Interest Expense	119	99	84
Allowance for funds used during construction — debt	(14)	(12)	(9)
Total interest charges and financing costs	105	87	75
Income before income taxes	285	289	252
Income taxes	(10)	26	39
Net income	$ 295	$ 263	$ 213