REGULATORY ASSETS & REGULATORY LIABILITIES 2 (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 66,526	$ 41,899
Excess Plant Removal Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	35,762	35,940
Conservation Incentive Program Payable
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	21,825	4,700
Societal Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	8,939	0
Other Regulatory Liablities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 0	$ 1,259