FINANCIAL INSTRUMENTS (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Schedule of Financial Instruments [Line Items]
Term	5 years
Carrying amount of long-term debt	$ 475,000,000	[1]	$ 450,000,000	[1]
Fair Value, Inputs, Level 1 [Member]
Schedule of Financial Instruments [Line Items]
Restricted investments held in escrow	100,000		100,000
Margin accounts with selected counterparties to support risk management activities	500,000		1,100,000
Fair Value, Inputs, Level 2 [Member]
Schedule of Financial Instruments [Line Items]
Estimated fair value of long-term debt	486,500,000		502,000,000
Carrying amount of long-term debt	475,000,000		450,000,000
Fair Value, Inputs, Level 2 [Member] | Financing Receivable [Member]
Schedule of Financial Instruments [Line Items]
Long-term receivables, net of unamortized discount	15,000,000		13,600,000
Imputed interest on long term receivables	$ 1,300,000		$ 1,300,000

[1] Long-term debt maturities and sinking funds requirements for the succeeding five years are as follows (in thousands): 2014, $21,000; 2015, $10,909; 2016, $27,909; 2017, $15,909; 2018, $38,909 .Our long-term debt agreements contain no financial covenants.