REGULATORY MATTERS Net Changes in Regulatory Assets and Liabilities (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($)
Revenue Accruals and Deferrals
Beginning balance	$ (2,564)
Net refund of 2014 revenue deferrals and accruals, including accrued interest	5,594
Net revenue accrual for the three months ended March 31, 2016	11,199
Net accrued interest payable for the three months ended March 31, 2016	(212)
Ending balance	$ 14,017