INVESTMENTS IN REAL ESTATE (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
INVESTMENTS IN REAL ESTATE
Land	$ 359,226,000		$ 363,612,000
Land improvements	26,613,000		26,747,000
Buildings and improvements	1,492,341,000		1,506,962,000
Furniture, fixtures, and equipment	8,149,000		9,720,000
Tenant improvements	147,303,000		146,205,000
Work in progress	12,361,000		8,126,000
Investments in real estate	2,045,993,000		2,061,372,000
Accumulated depreciation	(380,536,000)		(369,661,000)
Net investments in real estate	1,665,457,000		$ 1,691,711,000
Depreciation expense	$ 15,673,000	$ 16,280,000