CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Operating activities
Net income	$ 261,221	$ 236,570
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	250,343	253,004
Conservation and demand side management program amortization	1,555	1,712
Nuclear fuel amortization	28,862	27,522
Deferred income taxes	150,464	130,662
Amortization of investment tax credits	(1,443)	(1,657)
Allowance for equity funds used during construction	(21,907)	(19,754)
Equity earnings of unconsolidated subsidiaries	(7,438)	(7,577)
Dividends from unconsolidated subsidiaries	8,850	9,539
Share-based compensation expense	5,370	8,167
Net realized and unrealized hedging and derivative transactions	7,384	217
Changes in operating assets and liabilities:
Accounts receivable	(140,962)	(72,205)
Accrued unbilled revenues	111,417	76,602
Inventories	140,301	87,865
Other current assets	(66,320)	(51,203)
Accounts payable	(37,730)	5,311
Net regulatory assets and liabilities	(253)	88,572
Other current liabilities	1,008	20,318
Pension and other employee benefit obligations	(125,780)	(181,091)
Change in other noncurrent assets	48,054	24,594
Change in other noncurrent liabilities	(20,347)	5,160
Net cash provided by operating activities	592,649	642,328
Investing activities
Utility capital/construction expenditures	(822,628)	(752,251)
Proceeds from insurance recoveries	4,260	23,500
Allowance for equity funds used during construction	21,907	19,754
Purchases of investments in external decommissioning fund	(229,548)	(586,239)
Proceeds from the sale of investments in external decommissioning fund	227,901	584,948
Investment in WYCO Development LLC	(1,161)	(231)
Other, net	(1,501)	(2,745)
Net cash used in investing activities	(800,770)	(713,264)
Financing activities
Proceeds from (repayments of) short-term borrowings, net	6,000	(177,000)
Proceeds from issuance of long-term debt	295,999	494,282
Repayments of long-term debt, including reacquisition premiums	(224)	(251,367)
Proceeds from issuance of common stock	63,548	160,084
Dividends paid	(132,033)	(124,426)
Net cash provided by financing activities	233,290	101,573
Net change in cash and cash equivalents	25,169	30,637
Cash and cash equivalents at beginning of period	107,144	82,323
Cash and cash equivalents at end of period	132,313	112,960
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(152,522)	(153,498)
Cash (paid) received for income taxes, net	(164)	17,939
Supplemental disclosure of non-cash investing and financing transactions:
Property, plant and equipment additions in accounts payable	290,058	256,530
Issuance of common stock for reinvested dividends and 401(k) plans	$ 14,525	$ 18,791