Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities:
Net Margin including Non-controlling interest	$ 17,658	$ 11,896	$ 9,096
Adjustments to reconcile net margin to net cash provided by operating activities:
Depreciation and amortization	45,739	45,168	42,049
Other non-cash charges	18,177	18,706	17,766
Amortization of lease obligations	6,308	5,893	5,503
Interest on lease deposits	(2,984)	(2,910)	(2,841)
Change in current assets	11,151	(2,871)	(2,224)
Change in deferred energy	12,194	47,783	(57,141)
Change in current liabilities	(36,449)	62,694	9,204
Change in regulatory assets and liabilities	17,882	26,968	(2,467)
Change in deferred charges-other and deferred credits and other liabilities-other	(1,224)	5,973	(2,096)
Net Cash Provided by Operating Activities	88,452	219,300	16,849
Investing Activities:
Purchases of held to maturity securities	(480)	(130,293)	(3,931)
Proceeds from sale of held to maturity securities	960	130,240	21,746
Increase in other investments	(4,300)	(4,726)	(6,760)
Electric plant additions	(263,777)	(373,516)	(135,857)
Net Cash Used for Investing Activities	(267,597)	(378,295)	(124,802)
Financing Activities:
Issuance of long-term debt		332,000
Debt issuance costs		(1,754)
Payments of long-term debt	(28,292)	(28,292)	(28,292)
Draws on revolving credit facility	333,850	104,000	387,604
Repayments on revolving credit facility	(181,850)	(190,000)	(301,604)
Net Cash Provided by Financing Activities	123,708	215,954	57,708
Net Change in Cash and Cash Equivalents	(55,437)	56,959	(50,245)
Cash and Cash Equivalents - Beginning of Period	58,383	1,424	51,669
Cash and Cash Equivalents - End of Period	$ 2,946	$ 58,383	$ 1,424