Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities:
Net income	$ 45,174	$ 33,562	$ 30,173
Adjustments to reconcile net income to net cash provided by operating activities -
Depreciation and amortization	32,552	29,100	28,125
Deferred income taxes	7,690	16,518	13,582
AFUDC - equity	(918)	(519)	(368)
Employee benefits	2,403	1,295	3,094
Other adjustments	232	(2,330)	1,400
Change in operating assets and liabilities -
Accounts receivable and other current assets	(2,236)	(10,412)	(5,265)
Accounts payable and other current liabilities	21,652	10,829	1,180
Contributions to defined benefit pension plan	0	(1,696)	(2,299)
Regulatory assets	(3,839)	(5,366)	107
Regulatory liabilities	(2,479)	2,479	(17)
Other operating activities	(5,680)	(6,624)	(3,149)
Net cash provided by (used in) operating activities	94,551	66,836	66,563
Investing activities:
Property, plant and equipment additions	(56,795)	(82,826)	(74,390)
Notes receivable from affiliate companies, net	(36,687)	(51,334)	6,353
Other investing activities	(128)	(154)	(72)
Net cash provided by (used in) investing activities	(93,610)	(134,314)	(68,109)
Financing activities:
Long-term debt - repayments	0	(12,200)	0
Long-term debt - issuance	0	85,000	0
Other financing activities	(2)	(961)	0
Net cash provided by (used in) financing activities	(2)	71,839	0
Net change in cash and cash equivalents	939	4,361	(1,546)
Cash and cash equivalents:
Beginning of year	6,620	2,259	3,805
End of year	$ 7,559	$ 6,620	$ 2,259