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	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Line of Credit Facility [Line Items]
Interest incurred	$ 376	$ 655	$ 1,738	$ 1,541
Capitalized interest	$ 145	$ 180	$ 455	$ 392
Weighted average interest rate	4.30%	2.10%	2.10%	2.50%