Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 302,592	$ 244,765
Adjustments
Depreciation and amortization	280,652	262,543
Provision for deferred income taxes	197,001	144,627
Amortization of deferred investment tax credits	(1,139)	(1,156)
Provision for losses on utility accounts receivable	12,822	13,340
Allowance for other funds used during construction	(13,173)	(9,059)
Gain on asset dispositions and purchases	(657)	(1,339)
Pension and non-pension post retirement benefits	60,426	53,579
Other, net	(6,740)	32,363
Changes in assets and liabilities
Receivables and unbilled utility revenues	(96,978)	(55,647)
Income taxes receivable	(143)	(134)
Other current assets	(22,480)	(32,689)
Pension and non-pension post retirement benefit contributions	(96,036)	(134,821)
Accounts payable	(47,121)	(14,385)
Taxes accrued, including income taxes	33,721	17,289
Interest accrued	46,617	42,626
Change in book overdraft	36,206	0
Other current liabilities	49,444	14,142
Net cash provided by operating activities	735,014	576,044
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(680,357)	(621,940)
Acquisitions	(44,333)	(6,381)
Proceeds from sale of assets and securities	560,095	7,044
Removal costs from property, plant and equipment retirements, net	(38,606)	(38,915)
Net restricted funds released	17,845	54,191
Net cash used in investing activities	(185,356)	(606,001)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	14,730	12,350
Repayment of long-term debt	(261,309)	(68,689)
Net (repayments) borrowings under short-term debt agreements	(183,190)	211,543
Proceeds from issuances of employee stock plans and DRIP	22,062	10,363
Advances and contributions for construction, net of refunds of $10,748 and $15,142 at September 30, 2012 and 2011, respectively	22,182	15,767
Change in bank overdraft position	(34,812)	(31,111)
Debt issuance costs	0	(552)
Redemption of preferred stock	(3,927)	(140)
Dividends paid	(125,023)	(117,463)
Other	3,953	398
Net cash (used in) provided by financing activities	(545,334)	32,466
Net increase in cash and cash equivalents	4,324	2,509
Cash and cash equivalents at beginning of period	14,207	13,112
Cash and cash equivalents at end of period	18,531	15,621
Non-cash investing activity:
Capital expenditures acquired on account but unpaid at quarter-end	118,215	107,477
Non-cash financing activity:
Long-term debt	68,746	0
Dividends accrued	44,187	40,367
Advances and contributions	$ 9,185	$ 16,356