DERIVATIVE INSTRUMENTS (Details) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014
Not Designated as Hedging Instrument | Foreign Exchange Forward
Derivative [Line Items]
Number of foreign currency exchange forward contracts	2	2
Notional amount	$ 348,300,000	$ 348,300,000
Not Designated as Hedging Instrument | Foreign Exchange Forward | Gain (loss) on foreign exchange
Derivative [Line Items]
Gain (loss) on derivative, net	581,000	(6,209,000)
Not Designated as Hedging Instrument | Contracts to purchase power | Derivative loss
Derivative [Line Items]
Gain (loss) on derivative, net	(5,930,000)	(5,930,000)
Not Designated as Hedging Instrument | Contracts to purchase power | Other current liabilities
Derivative [Line Items]
Derivative Liability	140,000	140,000
Not Designated as Hedging Instrument | Contracts to purchase power | Other liabilities
Derivative [Line Items]
Derivative Liability	$ 5,790,000	$ 5,790,000
Minimum | Contracts to purchase power
Derivative [Line Items]
Contracted power price notional amount		41.05
Maximum | Contracts to purchase power
Derivative [Line Items]
Contracted power price notional amount		44.09