CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Operating revenues
Electric	$ 2,297,638	$ 2,219,877	$ 4,599,348	$ 4,312,073
Natural gas	369,127	341,321	1,248,815	1,010,917
Other	18,331	17,715	39,537	38,772
Total operating revenues	2,685,096	2,578,913	5,887,700	5,361,762
Operating expenses
Electric fuel and purchased power	1,041,322	1,011,044	2,108,643	1,936,087
Cost of natural gas sold and transported	210,901	188,765	834,729	628,140
Cost of sales — other	7,642	7,881	16,771	16,292
Operating and maintenance expenses	585,604	562,557	1,145,747	1,091,788
Conservation and demand side management program expenses	70,834	60,445	148,380	124,477
Depreciation and amortization	255,307	243,934	501,250	492,640
Taxes (other than income taxes)	116,278	102,051	240,980	215,478
Total operating expenses	2,287,888	2,176,677	4,996,500	4,504,902
Operating income	397,208	402,236	891,200	856,860
Other income, net	82	413	3,283	4,335
Equity earnings of unconsolidated subsidiaries	7,811	7,529	15,249	15,106
Allowance for funds used during construction — equity	23,608	22,109	45,515	41,863
Interest charges and financing costs
Interest charges — includes other financing costs of $5,614, $12,229, $11,406 and $18,038, respectively	139,400	146,853	278,494	286,484
Allowance for funds used during construction — debt	(10,113)	(10,316)	(19,661)	(19,074)
Total interest charges and financing costs	129,287	136,537	258,833	267,410
Income before income taxes	299,422	295,750	696,414	650,754
Income taxes	104,258	98,893	240,029	217,327
Net income	$ 195,164	$ 196,857	$ 456,385	$ 433,427
Weighted average common shares outstanding:
Basic (in shares)	503,272	497,747	501,408	493,786
Diluted (in shares)	503,456	498,036	501,612	494,303
Earnings per average common share:
Basic (in dollars per share)	$ 0.39	$ 0.40	$ 0.91	$ 0.88
Diluted (in dollars per share)	$ 0.39	$ 0.40	$ 0.91	$ 0.88
Cash dividends declared per common share (in dollars per share)	$ 0.30	$ 0.28	$ 0.60	$ 0.55