CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities
Net income	$ 74,636	$ 70,642	$ 59,468
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	92,656	80,875	78,048
Deferred income taxes	45,833	45,396	25,789
Amortization of Investment Tax Credits	(528)	(527)	(664)
Allowance for equity funds used during construction	(7,253)	(7,060)	(4,259)
Loss on Monticello LCM/EPU project	5,237	0	0
Provision for bad debts	3,947	4,431	3,988
Net derivative losses (gains)	482	10	(279)
Changes in operating assets and liabilities:
Accounts receivable	71	(5,558)	(12,702)
Accrued unbilled revenues	5,869	(1,933)	(2,496)
Inventories	3,126	(3,210)	(1,879)
Other current assets	7,135	(3,501)	(3,749)
Accounts payable	(7,626)	2,936	(1,811)
Net regulatory assets and liabilities	(27,114)	(34,697)	(2,062)
Other current liabilities	5,147	(911)	7,589
Pension and other employee benefit obligations	(3,177)	(6,134)	(8,759)
Change in other noncurrent assets	209	(113)	232
Change in other noncurrent liabilities	716	2,534	1,119
Net cash provided by operating activities	199,366	143,180	137,573
Investing activities
Utility capital/construction expenditures	(251,797)	(288,209)	(201,278)
Allowance for equity funds used during construction	7,253	7,060	4,259
Other, net	(224)	(166)	(421)
Net cash used in investing activities	(244,768)	(281,315)	(197,440)
Financing activities
Proceeds from (repayments of) short-term borrowings, net	(68,000)	10,000	29,000
Proceeds from notes payable to affiliates	0	30	0
Repayments Of Notes Payable To Affiliates	0	0	(80)
Proceeds from Issuance of Long-term Debt	97,969	98,534	0
Repayments of long-term debt	(87)	(107)	(160)
Capital contributions from parent	69,243	73,432	58,977
Dividends paid to parent	(53,929)	(43,818)	(30,980)
Net cash provided by financing activities	45,196	138,071	56,757
Net change in cash and cash equivalents	(206)	(64)	(3,110)
Cash and cash equivalents at beginning of period	1,285	1,349	4,459
Cash and cash equivalents at end of period	1,079	1,285	1,349
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(27,491)	(24,442)	(24,376)
Cash received (paid) for income taxes, net	5,762	3,474	(9,842)
Supplemental disclosure of non-cash investing transactions:
Property, plant and equipment additions in accounts payable	$ 16,729	$ 35,267	$ 27,222