Consolidated Statements of Income (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Revenues
Total revenues	$ 886,355	$ 694,541	$ 2,391,307	$ 1,969,245
Expenses
Total expenses	791,865	621,910	2,169,781	1,772,276
Operating income (loss)
Total operating income (loss)	94,490	72,631	221,526	196,969
Interest expense-other than on deposit liabilities and other bank borrowings	(19,949)	(21,015)	(64,266)	(61,916)
Allowance for borrowed funds used during construction	658	492	1,731	2,061
Allowance for equity funds used during construction	1,570	1,197	4,131	4,817
Income before income taxes	76,769	53,305	163,122	141,931
Income taxes	27,894	20,385	57,700	51,677
Net income	48,875	32,920	105,422	90,254
Preferred stock dividends of subsidiaries	471	471	1,417	1,417
Net income for common stock	48,404	32,449	104,005	88,837
Basic earnings per common share (in dollars per share)	$ 0.50	$ 0.35	$ 1.09	$ 0.95
Diluted earnings per common share (in dollars per share)	$ 0.50	$ 0.35	$ 1.09	$ 0.95
Dividends per common share (in dollars per share)	$ 0.31	$ 0.31	$ 0.93	$ 0.93
Weighted-average number of common shares outstanding (in shares)	95,873	93,699	95,365	93,148
Dilutive effect of share-based compensation (in shares)	227	192	306	257
Adjusted weighted-average shares (in shares)	96,100	93,891	95,671	93,405
Electric utility
Revenues
Total revenues	820,254	623,126	2,194,327	1,755,332
Expenses
Total expenses	745,298	571,783	2,031,645	1,619,945
Operating income (loss)
Total operating income (loss)	74,956	51,343	162,682	135,387
Income before income taxes	62,244	37,197	122,114	95,063
Income taxes	23,787	14,719	46,446	35,893
Net income	38,457	22,478	75,668	59,170
Preferred stock dividends of subsidiaries	498	498	1,496	1,496
Net income for common stock	37,959	21,980	74,172	57,674
Bank
Revenues
Total revenues	66,100	71,429	197,731	213,975
Expenses
Total expenses	42,931	47,040	128,988	142,040
Operating income (loss)
Total operating income (loss)	23,169	24,389	68,743	71,935
Income before income taxes	23,166	24,359	68,699	71,842
Income taxes	7,709	9,066	24,196	26,682
Net income	15,457	15,293	44,503	45,160
Net income for common stock	15,457	15,293	44,503	45,160
Other
Revenues
Total revenues	1	(14)	(751)	(62)
Expenses
Total expenses	3,636	3,087	9,148	10,291
Operating income (loss)
Total operating income (loss)	(3,635)	(3,101)	(9,899)	(10,353)
Income before income taxes	(8,641)	(8,251)	(27,691)	(24,974)
Income taxes	(3,602)	(3,400)	(12,942)	(10,898)
Net income	(5,039)	(4,851)	(14,749)	(14,076)
Preferred stock dividends of subsidiaries	(27)	(27)	(79)	(79)
Net income for common stock	$ (5,012)	$ (4,824)	$ (14,670)	$ (13,997)