RISK MANAGEMENT AND DERIVATIVE FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair value of derivative financial instruments
Total derivatives assets	$ 2	$ 233
Current liabilities	4,769	760
Non-current liabilities and deferred credits	5,081	3,564
Total derivatives liabilities	9,850	4,324
Non-designated as hedging instruments due to regulatory accounting | Commodity contracts | Gas
Fair value of derivative financial instruments
Current assets - Prepaid expenses and other		39
Non-current assets and deferred charges- Other	2	117
Current liabilities	967	252
Non-current liabilities and deferred credits	86	2
Non-designated as hedging instruments due to regulatory accounting | Commodity contracts | Electric
Fair value of derivative financial instruments
Non-current assets and deferred charges- Other		77
Current liabilities	3,802	508
Non-current liabilities and deferred credits	$ 4,995	$ 3,562