CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
OPERATING REVENUES	$ 915,822	$ 878,576	$ 1,602,474	$ 1,499,207
OPERATING EXPENSES
Fuel and purchased power	277,584	264,723	508,263	481,032
Operations and maintenance	229,300	216,236	452,550	426,899
Depreciation and amortization	106,292	100,606	210,022	200,715
Taxes other than income taxes	40,814	41,289	80,835	83,764
Other expenses	2,020	1,233	4,069	4,301
Total	656,010	624,087	1,255,739	1,196,711
OPERATING INCOME	259,812	254,489	346,735	302,496
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	6,265	5,175	13,129	9,931
Other income (Note 10)	469	177	1,227	937
Other expense (Note 10)	(2,234)	(2,669)	(5,986)	(6,737)
Total	4,500	2,683	8,370	4,131
INTEREST EXPENSE
Interest charges	51,307	53,000	100,785	109,967
Allowance for borrowed funds used during construction	(3,636)	(3,447)	(7,626)	(6,598)
Total	47,671	49,553	93,159	103,369
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	216,641	207,619	261,946	203,258
INCOME TAXES	77,043	76,689	89,512	72,044
INCOME FROM CONTINUING OPERATIONS	139,598	130,930	172,434	131,214
LOSS FROM DISCONTINUED OPERATIONS
Net of income tax benefit of $535 for three months ended June 30, 2012 and $1,040 for six months ended June 30, 2012		(819)		(1,584)
NET INCOME	139,598	130,111	172,434	129,630
Less: Net income attributable to noncontrolling interests (Note 6)	8,391	7,766	16,783	15,542
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	131,207	122,345	155,651	114,088
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)	109,962	109,491	109,898	109,395
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)	110,932	110,359	110,843	110,183
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Income from continuing operations attributable to common shareholders - basic (in dollars per share)	$ 1.19	$ 1.12	$ 1.42	$ 1.06
Net income attributable to common shareholders - basic (in dollars per share)	$ 1.19	$ 1.12	$ 1.42	$ 1.04
Income from continuing operations attributable to common shareholders - diluted (in dollars per share)	$ 1.18	$ 1.12	$ 1.40	$ 1.05
Net income attributable to common shareholders - diluted (in dollars per share)	$ 1.18	$ 1.11	$ 1.40	$ 1.04
DIVIDENDS DECLARED PER SHARE (in dollars per share)	$ 1.09	$ 1.05	$ 1.09	$ 1.575
AMOUNTS ATTRIBUTABLE TO COMMON SHAREHOLDERS:
Income from continuing operations, net of tax	131,207	123,164	155,651	115,681
Discontinued operations, net of tax		(819)		(1,593)
Net income attributable to common shareholders	$ 131,207	$ 122,345	$ 155,651	$ 114,088