CONDENSED CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
OPERATING REVENUES	$ 686,652	$ 620,631
OPERATING EXPENSES
Fuel and purchased power	230,679	216,309
Operations and maintenance	223,250	210,663
Depreciation and amortization	103,730	100,109
Taxes other than income taxes	40,021	42,475
Other expenses	2,049	3,068
Total	599,729	572,624
OPERATING INCOME	86,923	48,007
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction	6,864	4,756
Other income (Note 10)	758	760
Other expense (Note 10)	(3,752)	(4,068)
Total	3,870	1,448
INTEREST EXPENSE
Interest charges	49,478	56,967
Allowance for borrowed funds used during construction	(3,990)	(3,151)
Total	45,488	53,816
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	45,305	(4,361)
INCOME TAXES	12,469	(4,645)
INCOME FROM CONTINUING OPERATIONS	32,836	284
LOSS FROM DISCONTINUED OPERATIONS
Net of income tax benefit of $(505)		(765)
NET INCOME (LOSS)	32,836	(481)
Less: Net income attributable to noncontrolling interests (Note 6)	8,392	7,776
NET INCOME (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS	24,444	(8,257)
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)	109,832	109,299
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)	110,835	109,299
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Income (loss) from continuing operations attributable to common shareholders - basic (in dollars per share)	$ 0.22	$ (0.07)
Net income (loss) attributable to common shareholders - basic (in dollars per share)	$ 0.22	$ (0.08)
Income (loss) from continuing operations attributable to common shareholders - diluted (in dollars per share)	$ 0.22	$ (0.07)
Net income (loss) attributable to common shareholders - diluted (in dollars per share)	$ 0.22	$ (0.08)
DIVIDENDS DECLARED PER SHARE (in dollars per share)		$ 0.525
AMOUNTS ATTRIBUTABLE TO COMMON SHAREHOLDERS:
Income (loss) from continuing operations, net of tax	24,444	(7,483)
Discontinued operations, net of tax		(774)
Net income (loss) attributable to common shareholders	$ 24,444	$ (8,257)