CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating activities
Net income	$ 380,170	$ 381,135
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	271,150	253,764
Demand side management program amortization	3,658	4,042
Deferred income taxes	230,665	179,254
Amortization of investment tax credits	(2,219)	(1,955)
Allowance for equity funds used during construction	(21,529)	(10,961)
Net realized and unrealized hedging and derivative transactions	(9,052)	(39,241)
Changes in operating assets and liabilities:
Accounts receivable	61,660	50,612
Accrued unbilled revenues	80,347	110,880
Inventories	(28,021)	11,553
Prepayments and other	5,818	(33,967)
Accounts payable	(28,581)	(83,400)
Net regulatory assets and liabilities	74,709	(66,007)
Other current liabilities	(16,662)	(8,444)
Pension and other employee benefit obligations	(44,101)	(59,154)
Change in other noncurrent assets	6,917	(8,730)
Change in other noncurrent liabilities	7,744	(505)
Net cash provided by operating activities	972,673	678,876
Investing activities
Utility capital/construction expenditures	(742,822)	(610,309)
Allowance for equity funds used during construction	21,529	10,961
Investments in utility money pool arrangement	(1,086,000)	(820,000)
Repayments from utility money pool arrangement	951,000	752,000
Net cash used in investing activities	(856,293)	(667,348)
Financing activities
Repayments of short-term borrowings, net	(154,000)	0
Borrowings under utility money pool arrangement	14,000	36,000
Repayments under utility money pool arrangement	(14,000)	(36,000)
Proceeds from issuance of long-term debt	492,372	791,007
Repayments of long-term debt	(250,000)	0
Capital contributions from parent	4,485	28,122
Dividends paid to parent	(198,941)	(200,501)
Net cash (used in) provided by financing activities	(106,084)	618,628
Net change in cash and cash equivalents	10,296	630,156
Cash and cash equivalents at beginning of period	5,150	3,763
Cash and cash equivalents at end of period	15,446	633,919
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(131,378)	(133,667)
Cash received (paid) for income taxes, net	41,531	(51,240)
Supplemental disclosure of non-cash investing transactions:
Property, plant and equipment additions in accounts payable	$ 100,475	$ 79,597