REGULATED OPERATING EXPENSE (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Regulated Operating Expenses
Power operation expense (other than fuel)	$ 16,089	$ 15,643	$ 15,045
Electric transmission and distribution expense	27,919	21,863	17,083
Natural gas transmission and distribution expense	2,362	2,498	2,443
Customer accounts and assistance expense	11,239	11,180	10,211
Employee pension expense	10,590	10,736	10,180
Employee healthcare expense	9,147	10,190	9,825
General office supplies and expense	15,024	12,850	10,776
Administrative and general expense	14,385	14,800	15,091
Bad Debt Expense	3,420	3,665	3,038
Regulatory reversal of gain on sale of assets	44	1,236
Miscellaneous expense	472	672	679
Total	$ 110,691	$ 105,333	$ 94,371