CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating activities
Net income	$ 49,951	$ 51,006	$ 42,749
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	70,372	69,900	64,996
Deferred income taxes	27,107	35,610	20,714
Amortization of investment tax credits	(626)	(611)	(622)
Allowance for equity funds used during construction	(2,104)	(1,007)	(2,253)
Provision for bad debts	3,329	3,842	3,294
Net derivative losses	127	127	127
Changes in operating assets and liabilities:
Accounts receivable	(15,953)	(4,013)	15,556
Accrued unbilled revenues	(470)	2,911	(6,672)
Inventories	6,018	913	1,827
Other current assets	(3,172)	(1,180)	6,872
Accounts payable	5,828	(16,614)	(5,668)
Net regulatory assets and liabilities	3,623	10,008	(3,207)
Other current liabilities	3,681	(2,260)	1,131
Pension and other employee benefit obligations	(10,857)	(7,214)	(3,113)
Change in other noncurrent assets	14	564	867
Change in other noncurrent liabilities	(595)	(2,682)	5,260
Net cash provided by operating activities	136,273	139,300	141,858
Investing activities
Utility capital/construction expenditures	(152,759)	(140,982)	(128,933)
Allowance for equity funds used during construction	2,104	1,007	2,253
Other, net	916	(112)	2,291
Net cash used in investing activities	(149,739)	(140,087)	(124,389)
Financing activities
(Repayments of) proceeds from short-term borrowings, net	(27,000)	66,000	0
Proceeds from notes payable to affiliate	50	111,300	302,300
Repayments of notes payable to affiliate	0	(148,350)	(280,850)
Proceeds from issuance of long-term debt	97,916	0	0
Repayments of long-term debt	(97)	(96)	(95)
Capital contributions from parent	2,796	0	40,566
Dividends paid to parent	(57,311)	(32,941)	(73,868)
Net cash provided by (used in) financing activities	16,354	(4,087)	(11,947)
Net change in cash and cash equivalents	2,888	(4,874)	5,522
Cash and cash equivalents at beginning of period	1,571	6,445	923
Cash and cash equivalents at end of period	4,459	1,571	6,445
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(21,035)	(22,616)	(22,154)
Cash (paid) received for income taxes, net	(5,841)	1,116	4,371
Supplemental disclosure of non-cash investing transactions:
Property, plant and equipment additions in accounts payable	$ 10,618	$ 9,427	$ 3,630