CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	$ 366,940	$ 370,209
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of energy-related products and services business	(10,404)
Gain on sale of district cooling business		(41,973)
Depreciation and amortization including nuclear fuel	493,784	472,807
Deferred fuel and purchased power	69,166	93,631
Deferred fuel and purchased power amortization	(155,157)	(122,481)
Allowance for equity funds used during construction	(23,707)	(22,066)
Real estate impairment charges		16,731
Gain on real estate debt restructuring		(16,755)
Deferred income taxes	176,192	260,411
Change in derivative instruments fair value	4,064	2,688
Changes in current assets and liabilities:
Customer and other receivables	40,626	(67,943)
Accrued unbilled revenues	(21,947)	7,679
Materials, supplies and fossil fuel	(23,398)	12,276
Other current assets	(3,079)	9,375
Accounts payable	58,346	9,125
Accrued taxes and income tax receivable - net	12,068	24,222
Other current liabilities	20,358	2,921
Change in margin and collateral accounts - assets	33,349	(9,937)
Change in margin and collateral accounts - liabilities	29,731	(88,315)
Change in long term income tax receivable	(3,530)
Change in unrecognized tax benefits	8,410	(73,621)
Change in other regulatory liabilities	37,009	56,801
Change in other long-term assets	(41,722)	(47,940)
Change in other long-term liabilities	58,484	(97,388)
Net cash flow provided by operating activities	1,125,583	750,457
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(884,350)	(748,374)
Contributions in aid of construction	38,096	32,754
Allowance for borrowed funds used during construction	(18,358)	(16,778)
Proceeds from sale of district cooling business		100,300
Proceeds from sale of energy-related products and services business	45,111
Proceeds from nuclear decommissioning trust sales	497,780	560,469
Investment in nuclear decommissioning trust	(513,799)	(584,885)
Proceeds from sale of commercial real estate investments	1,375	72,038
Proceeds from sale of life insurance policies	55,444
Other	(3,306)	8,576
Net cash flow used for investing activities	(782,007)	(575,900)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	470,353
Repayment of long-term debt	(655,169)	(106,572)
Short-term borrowings and payments - net	(16,600)	(137,115)
Dividends paid on common stock	(221,728)	(216,979)
Common stock equity issuance	15,841	255,971
Distributions to noncontrolling interests	(10,210)	(11,403)
Other	(2,668)	6,351
Net cash flow used for financing activities	(420,181)	(209,747)
NET DECREASE IN CASH AND CASH EQUIVALENTS	(76,605)	(35,190)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	110,188	145,378
CASH AND CASH EQUIVALENTS AT END OF YEAR	$ 33,583	$ 110,188