STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities
Net income	$ 95,177	$ 106,369	$ 89,901
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	124,069	115,917	109,207
Demand side management program amortization	1,673	1,811	1,811
Deferred income taxes	36,475	54,119	55,508
Amortization of investment tax credits	(341)	(327)	(275)
Allowance for equity funds used during construction	(10,186)	(7,272)	(5,342)
Provision for bad debts	3,437	2,915	3,655
Gain on sale of transmission assets	(13,661)	0	0
Net derivative losses	268	269	268
Changes in operating assets and liabilities:
Accounts receivable	(36,184)	(3,429)	(23,518)
Accrued unbilled revenues	(10,315)	5,250	6,042
Inventories	(7,443)	4,238	(5,726)
Prepayments and other	4,456	(3,901)	(2,480)
Accounts payable	20,650	(13,730)	(1,527)
Net regulatory assets and liabilities	620	24,243	6,090
Other current liabilities	51,880	1,780	5,717
Pension and other employee benefit obligations	(17,968)	(13,706)	(7,576)
Change in other noncurrent assets	(2,281)	(1,541)	1,509
Change in other noncurrent liabilities	(2,689)	(1,912)	(4,299)
Net cash provided by operating activities	237,637	271,093	228,965
Investing activities
Utility capital/construction expenditures	(584,736)	(384,626)	(308,223)
Proceeds from sale of transmission assets	37,118	0	0
Allowance for equity funds used during construction	10,186	7,272	5,342
Investments in utility money pool arrangement	(12,000)	(217,000)	(40,300)
Receipts from utility money pool arrangement	12,000	217,000	40,300
Other, net	0	0	221
Net cash used in investing activities	(537,432)	(377,354)	(302,660)
Financing activities
Proceeds from (repayment of) short-term borrowings, net	75,000	9,000	(49,000)
Proceeds from issuance of long-term debt	94,626	108,678	193,137
Repayment of long-term debt	0	0	(101,800)
Borrowings under utility money pool arrangement	767,000	265,000	293,500
Repayments under utility money pool arrangement	(729,000)	(270,000)	(288,500)
Capital contributions from parent	162,277	60,024	89,631
Dividends paid to parent	(69,579)	(66,609)	(64,401)
Net cash provided by financing activities	300,324	106,093	72,567
Net change in cash and cash equivalents	529	(168)	(1,128)
Cash and cash equivalents at beginning of period	482	650	1,778
Cash and cash equivalents at end of period	1,011	482	650
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(67,209)	(61,268)	(57,122)
Cash paid for income taxes, net	(16,721)	(13,763)	(2,245)
Supplemental disclosure of non-cash investing transactions:
Property, plant and equipment additions in accounts payable	$ 23,305	$ 38,751	$ 23,570