CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
OPERATING REVENUES	$ 906,264	$ 915,822	$ 1,592,515	$ 1,602,474
OPERATING EXPENSES
Fuel and purchased power	290,854	277,584	540,640	508,263
Operations and maintenance	211,222	229,300	424,104	452,550
Depreciation and amortization	105,150	106,292	206,922	210,022
Taxes other than income taxes	44,004	40,814	89,849	80,835
Other expenses	921	2,020	1,717	4,069
Total	652,151	656,010	1,263,232	1,255,739
OPERATING INCOME	254,113	259,812	329,283	346,735
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	7,499	6,265	14,941	13,129
Other income (Note 10)	2,781	469	5,148	1,227
Other expense (Note 10)	(508)	(2,234)	(5,192)	(5,986)
Total	9,772	4,500	14,897	8,370
INTEREST EXPENSE
Interest charges	51,751	51,307	104,720	100,785
Allowance for borrowed funds used during construction	(3,790)	(3,636)	(7,560)	(7,626)
Total	47,961	47,671	97,160	93,159
INCOME BEFORE INCOME TAXES	215,924	216,641	247,020	261,946
INCOME TAXES	74,540	77,043	80,945	89,512
NET INCOME	141,384	139,598	166,075	172,434
Less: Net income attributable to noncontrolling interests (Note 6)	8,926	8,391	17,851	16,783
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 132,458	$ 131,207	$ 148,224	$ 155,651
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)	110,565	109,962	110,546	109,898
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)	111,002	110,932	110,925	110,843
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders - basic (in dollars per share)	$ 1.20	$ 1.19	$ 1.34	$ 1.42
Net income attributable to common shareholders - diluted (in dollars per share)	$ 1.19	$ 1.18	$ 1.34	$ 1.40
DIVIDENDS DECLARED PER SHARE (in dollars per share)	$ 1.14	$ 1.09	$ 1.14	$ 1.09