CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Operating revenues
Electric	$ 761,569	$ 747,882	$ 1,495,833	$ 1,469,230
Natural gas	223,187	209,296	679,524	593,220
Steam and other	8,948	9,251	21,890	21,436
Total operating revenues	993,704	966,429	2,197,247	2,083,886
Operating expenses
Electric fuel and purchased power	349,070	322,787	683,540	642,668
Cost of natural gas sold and transported	117,281	109,697	427,086	359,317
Cost of sales — steam and other	3,435	4,008	8,413	8,813
Operating and maintenance expenses	188,901	188,152	364,425	361,193
Demand side management program expenses	34,678	32,938	69,873	66,059
Depreciation and amortization	95,115	89,079	188,431	178,629
Taxes (other than income taxes)	41,787	36,093	83,605	71,233
Total operating expenses	830,267	782,754	1,825,373	1,687,912
Operating income	163,437	183,675	371,874	395,974
Other income, net	912	1,322	1,709	2,899
Allowance for funds used during construction — equity	12,952	6,791	24,382	12,714
Interest charges and financing costs
Interest charges — includes other financing costs of $1,532, $1,723, $3,252, and $3,371, respectively	42,429	43,231	86,401	84,619
Allowance for funds used during construction — debt	(4,812)	(3,100)	(9,020)	(5,251)
Total interest charges and financing costs	37,617	40,131	77,381	79,368
Income before income taxes	139,684	151,657	320,584	332,219
Income taxes	49,892	54,358	112,389	118,315
Net income	$ 89,792	$ 97,299	$ 208,195	$ 213,904