Regulated Operating Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Regulated Operating Expense
Electric transmission and distribution expense	$ 6,626	$ 7,414	$ 13,462	$ 14,514	$ 27,842	$ 28,757
Natural gas transmission and distribution expense	617	728	1,323	1,405	2,617	2,535
Power operation expense (other than fuel)	3,986	4,238	8,039	9,555	16,746	17,633
Customer accounts and assistance expense	2,809	2,790	5,540	5,493	10,984	11,013
Employee pension expense	2,644	2,718	5,269	5,401	10,654	10,764
Employee healthcare plan	2,437	2,384	4,682	4,618	10,226	9,433
General office supplies and expense	3,938	2,847	8,277	5,680	17,035	13,328
Administrative and general expense	3,542	3,440	7,658	7,997	14,524	14,718
Allowance for uncollectible accounts	800	1,018	879	1,345	1,614	2,664
Miscellaneous expense	86	92	200	211	419	585
Total	$ 27,485	$ 27,669	$ 55,329	$ 56,219	$ 112,661	$ 111,430