Consolidated Statements of Income (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
Revenues
Total revenues	$ 867,096	$ 829,168	$ 2,449,502	$ 2,405,967
Expenses
Total expenses	775,994	741,130	2,187,819	2,168,897
Operating income (loss)
Total operating income	91,102	88,038	261,683	237,070
Interest expense, net—other than on deposit liabilities and other bank borrowings	(19,170)	(19,043)	(58,648)	(56,216)
Allowance for borrowed funds used during construction	740	498	1,877	1,626
Allowance for equity funds used during construction	1,937	1,255	4,933	4,030
Income before income taxes	74,609	70,748	209,845	186,510
Income taxes	26,323	22,041	73,265	62,590
Net income	48,286	48,707	136,580	123,920
Preferred stock dividends of subsidiaries	471	471	1,417	1,417
Net income for common stock	47,815	48,236	135,163	122,503
Basic earnings per common share (in dollars per share)	$ 0.47	$ 0.49	$ 1.33	$ 1.24
Diluted earnings per common share (in dollars per share)	$ 0.46	$ 0.48	$ 1.32	$ 1.23
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)	102,416	99,204	101,768	98,670
Net effect of potentially dilutive shares (in shares)	610	614	710	620
Adjusted weighted-average shares (in shares)	103,026	99,818	102,478	99,290
Electric utility
Revenues
Total revenues	803,565	764,054	2,262,056	2,210,020
Expenses
Total expenses	727,409	694,201	2,045,166	2,030,071
Operating income (loss)
Total operating income	76,156	69,853	216,890	179,949
Income before income taxes	62,419	56,573	174,711	141,645
Income taxes	23,042	18,258	64,686	49,210
Net income	39,377	38,315	110,025	92,435
Preferred stock dividends of subsidiaries	498	498	1,496	1,496
Net income for common stock	38,879	37,817	108,529	90,939
Bank
Revenues
Total revenues	63,536	65,058	187,771	195,841
Expenses
Total expenses	43,964	42,223	129,528	126,550
Operating income (loss)
Total operating income	19,572	22,835	58,243	69,291
Income before income taxes	19,572	22,808	58,244	69,265
Income taxes	6,312	7,532	18,769	23,915
Net income	13,260	15,276	39,475	45,350
Net income for common stock	13,260	15,276	39,475	45,350
Other
Revenues
Total revenues	(5)	56	(325)	106
Expenses
Total expenses	4,621	4,706	13,125	12,276
Operating income (loss)
Total operating income	(4,626)	(4,650)	(13,450)	(12,170)
Income before income taxes	(7,382)	(8,633)	(23,110)	(24,400)
Income taxes	(3,031)	(3,749)	(10,190)	(10,535)
Net income	(4,351)	(4,884)	(12,920)	(13,865)
Preferred stock dividends of subsidiaries	(27)	(27)	(79)	(79)
Net income for common stock	$ (4,324)	$ (4,857)	$ (12,841)	$ (13,786)