CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating activities
Net income	$ 381,135	$ 308,366
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	253,764	249,396
Demand side management program amortization	4,042	6,484
Deferred income taxes	179,254	183,918
Amortization of investment tax credits	(1,955)	(2,002)
Allowance for equity funds used during construction	(10,961)	(5,373)
Net realized and unrealized hedging and derivative transactions	(39,241)	16,789
Changes in operating assets and liabilities:
Accounts receivable	50,612	12,232
Accrued unbilled revenues	110,880	77,382
Inventories	11,553	(38,563)
Prepayments and other	(33,967)	28,297
Accounts payable	(83,400)	(38,903)
Net regulatory assets and liabilities	(66,007)	14,038
Other current liabilities	(8,444)	2,508
Pension and other employee benefit obligations	(59,154)	(60,047)
Change in other noncurrent assets	(8,730)	3,467
Change in other noncurrent liabilities	(505)	(13,108)
Net cash provided by operating activities	678,876	744,881
Investing activities
Utility capital/construction expenditures	(610,309)	(475,444)
Allowance for equity funds used during construction	10,961	5,373
Investments in utility money pool arrangement	(820,000)	(268,300)
Repayments from utility money pool arrangement	752,000	199,300
Net cash used in investing activities	(667,348)	(539,071)
Financing activities
Repayments of short-term borrowings, net	0	(269,400)
Borrowings under utility money pool arrangement	36,000	203,800
Repayments under utility money pool arrangement	(36,000)	(203,800)
Proceeds from issuance of long-term debt	791,007	246,602
Capital contributions from parent	28,122	76,221
Dividends paid to parent	(200,501)	(202,636)
Net cash provided by (used in) financing activities	618,628	(149,213)
Net change in cash and cash equivalents	630,156	56,597
Cash and cash equivalents at beginning of period	3,763	32,912
Cash and cash equivalents at end of period	633,919	89,509
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(133,667)	(125,727)
Cash (paid) received for income taxes, net	(51,240)	30,575
Supplemental disclosure of non-cash investing transactions:
Property, plant and equipment additions in accounts payable	$ 79,597	$ 102,078