CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Operating revenues
Electric	$ 2,616,351	$ 2,599,925	$ 7,215,699	$ 6,911,998
Natural gas	236,649	205,358	1,485,464	1,216,275
Other	16,807	17,055	56,344	55,827
Total operating revenues	2,869,807	2,822,338	8,757,507	8,184,100
Operating expenses
Electric fuel and purchased power	1,079,855	1,097,944	3,188,498	3,034,031
Cost of natural gas sold and transported	99,344	74,847	934,073	702,987
Cost of sales — other	8,012	7,540	24,783	23,832
Operating and maintenance expenses	568,391	575,305	1,714,138	1,667,093
Conservation and demand side management program expenses	75,172	67,811	223,552	192,288
Depreciation and amortization	255,395	228,491	756,645	721,131
Taxes (other than income taxes)	117,958	105,287	358,938	320,765
Total operating expenses	2,204,127	2,157,225	7,200,627	6,662,127
Operating income	665,680	665,113	1,556,880	1,521,973
Other income (expense), net	1,404	(404)	4,687	3,931
Equity earnings of unconsolidated subsidiaries	7,401	7,273	22,650	22,379
Allowance for funds used during construction — equity	23,337	21,284	68,852	63,147
Interest charges and financing costs
Interest charges — includes other financing costs of $5,737, $6,020, $17,144 and $24,058, respectively	143,219	144,542	421,713	431,026
Allowance for funds used during construction — debt	(9,948)	(9,377)	(29,609)	(28,451)
Total interest charges and financing costs	133,271	135,165	392,104	402,575
Income before income taxes	564,551	558,101	1,260,965	1,208,855
Income taxes	195,969	193,349	435,998	410,676
Net income	$ 368,582	$ 364,752	$ 824,967	$ 798,179
Weighted average common shares outstanding:
Basic (in shares)	506,082	498,149	502,983	495,256
Diluted (in shares)	506,365	498,641	503,213	495,767
Earnings per average common share:
Basic (in dollars per share)	$ 0.73	$ 0.73	$ 1.64	$ 1.61
Diluted (in dollars per share)	$ 0.73	$ 0.73	$ 1.64	$ 1.61
Cash dividends declared per common share (in dollars per share)	$ 0.30	$ 0.28	$ 0.90	$ 0.83