Consolidated Condensed Statements of Income and Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues
Electric	$ 411	$ 461
Gas	128	136
Total revenues	539	597
Expenses
Fuel	107	122
Purchased power	4	13
Cost of natural gas sold	$ 47	$ 55
Type of Cost, Good or Service [Extensible List]	us-gaap:OilAndGasMember	us-gaap:OilAndGasMember
Operations and maintenance	$ 130	$ 157
Depreciation and amortization	92	93
Taxes, other than income	50	52
Total expenses	430	492
Income from operations	109	105
Other income
Allowance for equity funds used during construction	2	0
Other income, net	2	2
Total other income	4	2
Interest charges
Interest expense	34	30
Allowance for borrowed funds used during construction	(1)	0
Total interest charges	33	30
Income before provision for income taxes	80	77
Provision for income taxes	16	14
Net income	64	63
Comprehensive income	$ 64	$ 63