NOTES PAYABLE TO BANKS - Interest incurred on credit facility, interest capitalized related to facilities and equipment under construction, and related weighted average interest rates (Details) (Revolving credit facility, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Revolving credit facility
Line of Credit Facility [Line Items]
Interest incurred	$ 844	$ 414
Capitalized interest	$ 179	$ 97
Weighted average interest rate	1.60%	3.40%