CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating revenues
Electric	$ 877,604	$ 897,516	$ 2,318,912	$ 2,337,547
Natural gas	142,389	152,763	691,302	659,738
Steam and other	10,300	8,898	31,529	29,585
Total operating revenues	1,030,293	1,059,177	3,041,743	3,026,870
Operating expenses
Electric fuel and purchased power	288,997	318,624	857,346	890,509
Cost of natural gas sold and transported	37,243	42,379	303,903	270,182
Cost of sales — steam and other	4,098	3,664	11,991	10,874
Operating and maintenance expenses	173,905	191,011	547,413	570,343
Demand side management expenses	34,520	31,015	92,552	88,094
Depreciation and amortization	118,289	111,803	350,796	330,593
Taxes (other than income taxes)	47,213	45,076	146,481	146,851
Total operating expenses	704,265	743,572	2,310,482	2,307,446
Operating income	326,028	315,605	731,261	719,424
Other income, net	1,536	544	7,085	1,837
Allowance for funds used during construction — equity	8,642	5,343	19,591	13,714
Interest charges and financing costs
Interest charges — includes other financing costs of $1,605, $1,271, $4,669 and $4,735, respectively	49,097	46,664	141,403	138,982
Allowance for funds used during construction — debt	(3,266)	(1,995)	(7,610)	(5,222)
Total interest charges and financing costs	45,831	44,669	133,793	133,760
Income before income taxes	290,375	276,823	624,144	601,215
Income taxes	104,298	103,216	225,934	224,390
Net income	$ 186,077	$ 173,607	$ 398,210	$ 376,825