CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating revenues
Electric	$ 884,305	$ 881,102	$ 2,385,297	$ 2,376,935
Natural gas	151,553	159,808	716,731	839,332
Steam and other	8,846	8,201	30,647	30,091
Total operating revenues	1,044,704	1,049,111	3,132,675	3,246,358
Operating expenses
Electric fuel and purchased power	311,347	368,860	930,107	1,052,400
Cost of natural gas sold and transported	44,953	60,073	354,825	487,159
Cost of sales — steam and other	3,596	3,538	12,938	11,951
Operating and maintenance expenses	186,379	185,510	560,021	549,935
Demand side management program expenses	33,040	36,120	96,622	105,993
Depreciation and amortization	104,228	95,075	305,517	283,506
Taxes (other than income taxes)	45,987	38,862	146,895	122,467
Total operating expenses	729,530	788,038	2,406,925	2,613,411
Operating income	315,174	261,073	725,750	632,947
Other income, net	1,222	1,720	2,674	3,429
Allowance for funds used during construction — equity	3,958	12,315	10,155	36,697
Interest charges and financing costs
Interest charges — includes other financing costs of $1,611, $1,546, $4,671 and $4,798, respectively	44,875	42,540	131,859	128,941
Allowance for funds used during construction — debt	(1,467)	(4,564)	(3,890)	(13,584)
Total interest charges and financing costs	43,408	37,976	127,969	115,357
Income before income taxes	276,946	237,132	610,610	557,716
Income taxes	103,865	82,973	228,063	195,362
Net income	$ 173,081	$ 154,159	$ 382,547	$ 362,354