Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenues
Revenues from external customers	$ 783,749	$ 782,232
Expenses
Total expenses	695,443	713,407
Operating income (loss)
Total operating income	88,306	68,825
Interest expense, net—other than on deposit liabilities and other bank borrowings	(19,456)	(18,731)
Allowance for borrowed funds used during construction	614	730
Allowance for equity funds used during construction	1,609	1,215
Income before income taxes	71,073	52,039
Income taxes	24,673	17,887
Net income	46,400	34,152
Preferred stock dividends of subsidiaries	473	473
Net income for common stock	45,927	33,679
Basic earnings per common share (in dollars per share)	$ 0.45	$ 0.34
Diluted earnings per common share (in dollars per share)	$ 0.45	$ 0.34
Dividends per common share (in dollars per share)	$ 0.31	$ 0.31
Weighted-average number of common shares outstanding (in shares)	101,382	98,135
Net effect of potentially dilutive shares (in shares)	783	405
Adjusted weighted-average shares (in shares)	102,165	98,540
Electric utility
Revenues
Revenues from external customers	720,062	717,441
Expenses
Total expenses	649,396	666,320
Operating income (loss)
Total operating income	70,666	51,121
Income before income taxes	57,166	38,547
Income taxes	21,247	13,619
Net income	35,919	24,928
Preferred stock dividends of subsidiaries	499	499
Net income for common stock	35,420	24,429
Bank
Revenues
Revenues from external customers	63,619	64,756
Expenses
Total expenses	41,996	43,005
Operating income (loss)
Total operating income	21,623	21,751
Income before income taxes	21,624	21,752
Income taxes	7,085	7,597
Net income	14,539	14,155
Net income for common stock	14,539	14,155
Other
Revenues
Revenues from external customers	68	35
Expenses
Total expenses	4,051	4,082
Operating income (loss)
Total operating income	(3,983)	(4,047)
Income before income taxes	(7,717)	(8,260)
Income taxes	(3,659)	(3,329)
Net income	(4,058)	(4,931)
Preferred stock dividends of subsidiaries	(26)	(26)
Net income for common stock	$ (4,032)	$ (4,905)