CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
OPERATING REVENUES	$ 686,251	$ 686,652
OPERATING EXPENSES
Fuel and purchased power	249,786	230,679
Operations and maintenance	212,882	223,250
Depreciation and amortization	101,772	103,730
Taxes other than income taxes	45,845	40,021
Other expenses	796	2,049
Total	611,081	599,729
OPERATING INCOME	75,170	86,923
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	7,442	6,864
Other income (Note 10)	2,367	758
Other expense (Note 10)	(4,684)	(3,752)
Total	5,125	3,870
INTEREST EXPENSE
Interest charges	52,969	49,478
Allowance for borrowed funds used during construction	(3,770)	(3,990)
Total	49,199	45,488
INCOME BEFORE INCOME TAXES	31,096	45,305
INCOME TAXES	6,405	12,469
NET INCOME	24,691	32,836
Less: Net income attributable to noncontrolling interests (Note 6)	8,925	8,392
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 15,766	$ 24,444
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)	110,257	109,832
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)	110,888	110,835
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders - basic (in dollars per share)	$ 0.14	$ 0.22
Net income attributable to common shareholders - diluted (in dollars per share)	$ 0.14	$ 0.22