FINANCIAL INSTRUMENTS 3 (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Schedule of Equity Method Investments [Line Items]
Finance obligation to ACB Energy Partners LLC	$ 21,646,000		$ 22,549,000
Carrying amount of long-term debt	626,400,000	[1]	426,400,000	[1]
Marina Energy LLC [Member] | Energenic US LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity interest of Marina in Energenic	50.00%
Other construction costs	23,600,000		23,500,000
Fair Value, Inputs, Level 2 [Member]
Schedule of Equity Method Investments [Line Items]
Estimated fair value of long-term debt	682,300,000		533,400,000
Carrying amount of long-term debt	$ 626,400,000		$ 426,400,000

[1] Long-term debt maturities and sinking funds requirements for the succeeding five years are as follows (in thousands): 2013, $25,000; 2014, $21,000; 2015, $74,909; 2016, $27,909; 2017, $31,909.