CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 24,691	$ 32,836
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	122,394	124,344
Deferred fuel and purchased power	31,630	31,194
Deferred fuel and purchased power amortization	8,022	1,122
Allowance for equity funds used during construction	(7,442)	(6,864)
Deferred income taxes	8,810	(9,265)
Deferred investment tax credit	(247)	21,428
Change in derivative instruments fair value	(13)	333
Changes in current assets and liabilities:
Customer and other receivables	25,986	3,931
Accrued unbilled revenues	7,889	4,698
Materials, supplies and fossil fuel	(187)	(9,386)
Income tax receivable	130,870	(433)
Other current assets	(10,669)	(2,525)
Accounts payable	(50,990)	11,925
Accrued taxes	48,139	39,615
Other current liabilities	(15,864)	(62,636)
Change in margin and collateral accounts - assets	(290)	933
Change in margin and collateral accounts - liabilities	(29,075)	24,205
Change in other long-term assets	(9,636)	(31,202)
Change in other long-term liabilities	(34,861)	37,904
Net cash flow provided by operating activities	249,157	212,157
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(207,459)	(182,859)
Contributions in aid of construction	7,736	14,912
Allowance for borrowed funds used during construction	(3,770)	(3,990)
Proceeds from nuclear decommissioning trust sales	103,157	135,240
Investment in nuclear decommissioning trust	(107,470)	(139,553)
Other	(702)	(470)
Net cash flow used for investing activities	(208,508)	(176,720)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	250,000	104,307
Short-term borrowings and payments - net	(143,625)	(92,175)
Dividends paid on common stock	(62,520)	(58,067)
Common stock equity issuance	9,390	9,441
Other	1	(36)
Net cash flow provided by (used for) financing activities	53,246	(36,530)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	93,895	(1,093)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	9,526	26,202
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$ 103,421	$ 25,109