CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
NET INCOME (LOSS)	$ (481)	$ (9,674)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	118,487	123,298
Deferred fuel and purchased power	46,754	49,947
Deferred fuel and purchased power amortization	(24,514)	(31,238)
Allowance for equity funds used during construction	(4,756)	(5,395)
Deferred income taxes	(1,989)	(41,005)
Change in mark-to-market valuations	1,985	(284)
Changes in current assets and liabilities:
Customer and other receivables	52,264	75,528
Accrued unbilled revenues	20,511	9,633
Materials, supplies and fossil fuel	(13,753)	21,421
Other current assets	(3,502)	(636)
Accounts payable	(39,355)	(24,543)
Accrued taxes and income tax receivable - net	37,398	52,944
Other current liabilities	(39,804)	(37,406)
Change in unrecognized tax benefits		18,959
Change in margin and collateral accounts - assets	(1,853)	4,220
Change in margin and collateral accounts - liabilities	(32,950)	35,478
Change in other long-term assets	(21,469)	(33,169)
Change in other long-term liabilities	22,362	35,418
Net cash flow provided by operating activities	115,335	243,496
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(240,973)	(191,553)
Contributions in aid of construction	13,871	9,136
Allowance for borrowed funds used during construction	(3,151)	(3,576)
Proceeds from nuclear decommissioning trust sales	92,047	189,318
Investment in nuclear decommissioning trust	(96,360)	(194,241)
Other	(533)	(1,879)
Net cash flow used for investing activities	(235,099)	(192,795)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	319,081	175,000
Repayment of long-term debt	(375,727)	(175,170)
Short-term borrowings and payments - net	216,600	700
Dividends paid on common stock	(55,595)	(55,300)
Common stock equity issuance	4,289	11,727
Other	(1,757)	(3,653)
Net cash flow provided by (used for) financing activities	106,891	(46,696)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(12,873)	4,005
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	33,583	110,188
CASH AND CASH EQUIVALENTS AT END OF PERIOD	20,710	114,193
Cash paid during the period for:
Income taxes, net of (refunds)	(650)
Interest, net of amounts capitalized	$ 62,892	$ 55,997