Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 369,264	$ 358,070	$ 309,613
Adjustments
Depreciation and amortization	407,718	381,503	351,821
Provision for deferred income taxes	250,500	200,440	195,494
Amortization of deferred investment tax credits	(1,501)	(1,518)	(1,542)
Provision for losses on accounts receivable	26,953	26,701	19,952
Allowance for other funds used during construction	(12,639)	(15,592)	(13,131)
(Gain) loss on asset dispositions and purchases	925	(839)	(993)
Pension and non-pension postretirement benefits	78,069	87,289	71,439
Stock-based compensation expense	12,474	11,470	10,008
Other, net	(727)	(1,328)	44,521
Changes in assets and liabilities
Receivables and unbilled revenues	(79,306)	(34,528)	(34,819)
Taxes receivable, including income taxes	3,816	(1,922)	(1,199)
Other current assets	672	(5,223)	(1,305)
Pension and non-pension postretirement benefit contributions	(97,500)	(129,410)	(186,730)
Accounts payable	16,215	(10,572)	37,824
Taxes accrued, including income taxes	(30,182)	48,440	4,274
Interest accrued	(1,723)	(5,647)	(1,417)
Change in book overdraft	(32,120)	34,172	0
Other current liabilities	(14,746)	14,092	4,547
Net cash provided by operating activities	896,162	955,598	808,357
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(980,252)	(928,574)	(924,858)
Acquisitions	(23,658)	(44,560)	(7,220)
Proceeds from sale of assets and securities	918	561,739	9,972
Removal costs from property, plant and equipment retirements, net	(64,727)	(57,101)	(53,134)
Net funds released	14,425	86,140	62,843
Net cash used in investing activities	(1,053,294)	(382,356)	(912,397)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	404,157	315,430	12,510
Repayment of long-term debt	(493,095)	(471,954)	(70,045)
Proceeds from short-term borrowings with maturities greater than three months	221,000	0	0
Net short-term borrowings (repayments) with maturities less than three months	139,322	(211,064)	303,024
Proceeds from issuances of employee stock plans and DRIP	26,351	27,860	13,866
Advances and contributions for construction, net of refunds of $23,351 in 2013, $17,850 in 2012 and $21,061 in 2011	19,251	31,909	22,298
Change in bank overdraft position	0	(34,812)	(16,862)
Debt issuance costs	(4,503)	(7,393)	(552)
Redemption of preferred stocks	(3,370)	(4,376)	(1,888)
Dividends paid	(149,450)	(213,459)	(157,855)
Other	0	4,843	639
Net cash provided by (used in) financing activities	159,663	(563,016)	105,135
Net increase in cash and cash equivalents	2,531	10,226	1,095
Cash and cash equivalents at beginning of period	24,433	14,207	13,112
Cash and cash equivalents at end of period	26,964	24,433	14,207
Cash paid during the year for:
Interest, net of capitalized amount	317,826	329,331	331,944
Income taxes, net of refunds of $127 in 2013, $766 in 2012 and $812 in 2011	7,788	5,352	14,269
Non-cash investing activity
Capital expenditures acquired on account but unpaid as of year end	128,902	159,119	104,816
Non-cash financing activity
Advances and contributions	17,590	12,279	23,504
Dividends accrued	49,909	0	40,403
Long-term debt	6,702	68,746	0
Long-term debt retired	$ (3,565)	$ 0	$ 0