SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Non-Regulated Revenue
Maximum project completion period, less than (in months)	3
Allowance for doubtful accounts
Activities in the allowance for doubtful accounts
Beginning Balance	$ 804	$ 847	$ 1,210
Provision for uncollectible accounts	1,250	1,500	1,462
Net write off of uncollectible accounts	(1,385)	(1,543)	(1,825)
Ending Balance	$ 669	$ 804	$ 847