INVESTMENTS IN REAL ESTATE (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
INVESTMENTS IN REAL ESTATE
Land	$ 363,612,000	$ 354,035,000
Land improvements	26,747,000	28,071,000
Buildings and improvements	1,506,962,000	1,501,603,000
Furniture, fixtures, and equipment	9,720,000	10,875,000
Tenant improvements	146,205,000	131,446,000
Work in progress	8,126,000	10,764,000
Investments in real estate	2,061,372,000	2,036,794,000
Accumulated depreciation	(369,661,000)	(320,857,000)
Net investments in real estate	1,691,711,000	1,715,937,000
Depreciation expense	$ 61,915,000	$ 58,635,000	$ 58,013,000