DERIVATIVE INSTRUMENTS (Tables)

6 Months Ended

Jun. 30, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location

The effect of derivative instruments not designated as hedging instruments on the accompanying unaudited Consolidated Statements of Operations was as follows (in thousands):

		Three Months Ended June 30,					Six Months Ended June 30,
Derivative Instruments	Statements of Operations Location	2018		2017			2018		2017
Contracts to purchase power	Derivative loss (gain)	$	—	$	2,026		$	—	$	3,242
Contract to sell power	Derivative loss (gain)	—		(1,545		)	—		(5,146		)
		$	—	$	481		$	—	$	(1,904	)