SEGMENT DISCLOSURE - Reconciliation Of Segment Operating Income (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment disclosure
Asset management and other fees to related parties	$ (6,896,000)	$ (8,496,000)	$ (23,459,000)	$ (25,503,000)
Interest expense	(9,359,000)	(10,276,000)	(28,645,000)	(24,386,000)
General and administrative	(1,342,000)	(2,226,000)	(4,668,000)	(6,299,000)
Transaction costs	(242,000)	(53,000)	(11,870,000)	(320,000)
Depreciation and amortization	(13,472,000)	(17,724,000)	(45,464,000)	(54,262,000)
Impairment of real estate	0	0	(13,100,000)	0
Gain on sale of real estate	74,715,000	14,927,000	378,732,000	39,666,000
INCOME FROM CONTINUING OPERATIONS BEFORE PROVISION FOR INCOME TAXES	72,730,000	8,761,000	358,891,000	34,905,000
Provision for income taxes	(339,000)	(379,000)	(1,193,000)	(1,040,000)
NET INCOME FROM CONTINUING OPERATIONS	72,391,000	8,382,000	357,698,000	33,865,000
Discontinued Operations
Income from operations of assets held for sale	0	703,000	0	3,061,000
NET INCOME FROM DISCONTINUED OPERATIONS	0	703,000	0	3,061,000
NET INCOME	72,391,000	9,085,000	357,698,000	36,926,000
Net loss (income) attributable to noncontrolling interests	4,000	3,000	(10,000)	(9,000)
NET INCOME ATTRIBUTABLE TO THE COMPANY	72,395,000	9,088,000	357,688,000	36,917,000
Reportable segments
Segment disclosure
INCOME FROM CONTINUING OPERATIONS BEFORE PROVISION FOR INCOME TAXES	27,899,000	30,279,000	102,483,000	99,892,000
Corporate and Reconciling Items
Segment disclosure
Asset management and other fees to related parties	(6,051,000)	(7,631,000)	(20,986,000)	(22,824,000)
Interest expense	(9,243,000)	(10,152,000)	(28,442,000)	(24,080,000)
General and administrative	(876,000)	(885,000)	(2,462,000)	(3,167,000)
Transaction costs	(242,000)	(53,000)	(11,870,000)	(320,000)
Depreciation and amortization	(13,472,000)	(17,724,000)	(45,464,000)	(54,262,000)
Impairment of real estate	0	0	(13,100,000)	0
Gain on sale of real estate	$ 74,715,000	$ 14,927,000	$ 378,732,000	$ 39,666,000