CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating activities
Net income	$ 188,692	$ 167,648
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	166,460	162,890
Demand side management program amortization	2,785	5,091
Deferred income taxes	117,034	89,067
Amortization of investment tax credits	(1,303)	(1,335)
Allowance for equity funds used during construction	(6,274)	(3,417)
Net derivative losses	5,953	19,310
Changes in operating assets and liabilities:
Accounts receivable	57,355	35,878
Accrued unbilled revenues	100,953	73,003
Inventories	69,268	20,067
Prepayments and other	(34,380)	28,819
Accounts payable	(106,008)	(37,276)
Net regulatory assets and liabilities	(33,991)	(32,457)
Other current liabilities	(54,416)	(15,066)
Pension and other employee benefit obligations	(38,190)	(58,054)
Change in other noncurrent assets	(7,450)	(162)
Change in other noncurrent liabilities	(4,737)	(11,442)
Net cash provided by operating activities	421,751	442,564
Investing activities
Utility capital/construction expenditures	(382,676)	(278,282)
Allowance for equity funds used during construction	6,274	3,417
Investments in utility money pool arrangement	(610,000)	(3,300)
Repayments from utility money pool arrangement	662,000	3,300
Net cash used in investing activities	(324,402)	(274,865)
Financing activities
Proceeds from (repayments of) short-term borrowings, net	5,000	(120,400)
Borrowings under utility money pool arrangement	19,000	176,500
Repayments under utility money pool arrangement	(14,000)	(176,500)
Capital contributions from parent	28,122	76,221
Dividends paid to parent	(134,004)	(135,047)
Net cash used in financing activities	(95,882)	(179,226)
Net change in cash and cash equivalents	1,467	(11,527)
Cash and cash equivalents at beginning of period	3,763	32,912
Cash and cash equivalents at end of period	5,230	21,385
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(90,642)	(86,865)
Cash (paid) received for income taxes, net	(33,342)	35,043
Supplemental disclosure of non-cash investing transactions:
Property, plant and equipment additions in accounts payable	$ 58,967	$ 88,364