Consolidated Condensed Statements of Income and Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues
Electric	$ 509	$ 542	$ 970	$ 984
Gas	110	102	246	213
Total revenues	619	644	1,216	1,197
Expenses
Fuel	133	165	255	296
Purchased power	14	8	27	15
Operations and maintenance	162	131	319	259
Depreciation and amortization	89	88	182	173
Taxes, other than income	51	49	103	98
Total expenses	488	476	980	912
Income from operations	131	168	236	285
Other income
Allowance for equity funds used during construction	1	0	1	1
Other income, net	2	2	4	4
Total other income	3	2	5	5
Interest charges
Interest on long-term debt	27	28	54	56
Other interest	3	2	6	4
Allowance for borrowed funds used during construction	(1)	0	(1)	(1)
Total interest charges	29	30	59	59
Income before provision for income taxes	105	140	182	231
Provision for income taxes	20	54	34	89
Net income	85	86	148	142
Other comprehensive income, net of tax
Gain on cash flow hedges	1	0	1	1
Total other comprehensive income, net of tax	1	0	1	1
Comprehensive income	86	86	149	143
Cost of Natural Gas Sold [Member]
Expenses
Cost of goods and services sold	$ 39	$ 35	$ 94	$ 71