CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 129,630	$ 84,165
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	239,743	245,700
Deferred fuel and purchased power	82,261	64,679
Deferred fuel and purchased power amortization	(54,388)	(68,762)
Allowance for equity funds used during construction	(9,931)	(11,319)
Deferred income taxes	66,142	11,945
Change in derivative instruments fair value	(2,618)	(279)
Changes in current assets and liabilities:
Customer and other receivables	(21,424)	43,271
Accrued unbilled revenues	(43,211)	(60,390)
Materials, supplies and fossil fuel	(21,012)	(18,226)
Other current assets	(9,407)	(37,053)
Accounts payable	9,199	37,817
Accrued taxes and income tax receivable - net	19,775	29,530
Other current liabilities	807	3,967
Change in margin and collateral accounts - assets	124	21,185
Change in margin and collateral accounts - liabilities	69,602	39,567
Change in unrecognized tax benefits		18,959
Change in other long-term assets	(1,692)	(26,225)
Change in other long-term liabilities	5,035	57,748
Net cash flow provided by operating activities	458,635	436,279
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(424,775)	(387,272)
Contributions in aid of construction	25,800	21,905
Allowance for borrowed funds used during construction	(6,598)	(7,432)
Proceeds from nuclear decommissioning trust sales	211,138	299,600
Investment in nuclear decommissioning trust	(219,762)	(308,222)
Proceeds from sale of life insurance policies		55,444
Other	(525)	(2,352)
Net cash flow used for investing activities	(414,722)	(328,329)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	351,081	175,000
Repayment of long-term debt	(421,451)	(187,962)
Short-term borrowings and payments - net	109,000	(9,300)
Dividends paid on common stock	(111,297)	(112,537)
Common stock equity issuance	8,869	14,520
Distributions to noncontrolling interests	(2,630)	(2,610)
Other	160	(2,975)
Net cash flow used for financing activities	(66,268)	(125,864)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(22,355)	(17,914)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	33,583	110,188
CASH AND CASH EQUIVALENTS AT END OF PERIOD	11,228	92,274
Cash paid during the period for:
Income taxes, net of (refunds)	(649)
Interest, net of amounts capitalized	$ 94,680	$ 110,659