SEGMENT DISCLOSURE - Results of Operations (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment disclosure
Asset management and other fees to related parties									$ (24,451,000)	$ (30,251,000)	$ (33,882,000)
Interest expense									(27,702,000)	(36,338,000)	(34,385,000)
General and administrative									(9,167,000)	(5,479,000)	(7,961,000)
Transaction costs									(938,000)	(11,862,000)	(340,000)
Depreciation and amortization									(53,228,000)	(58,364,000)	(71,968,000)
Impairment of real estate									0	(13,100,000)	0
Gain on sale of real estate					$ 23,005,000	$ 74,715,000	$ 116,283,000	$ 187,734,000	0	401,737,000	39,666,000
Provision for income taxes									(925,000)	(1,376,000)	(1,646,000)
Net income from continuing operations	$ (900,000)	$ (529,000)	$ 1,949,000	$ 622,000	22,060,000	72,391,000	91,372,000	193,935,000	1,142,000	379,758,000	30,712,000
Discontinued operations:
Income from operations of assets held for sale									0	0	3,853,000
Gain on disposition of assets held for sale									0	0	0
NET INCOME FROM DISCONTINUED OPERATIONS									0	0	3,853,000
NET INCOME	(900,000)	(529,000)	1,949,000	622,000	22,060,000	72,391,000	91,372,000	193,935,000	1,142,000	379,758,000	34,565,000
Net income attributable to noncontrolling interests									(21,000)	(21,000)	(18,000)
NET INCOME ATTRIBUTABLE TO THE COMPANY	$ (906,000)	$ (528,000)	$ 1,937,000	$ 618,000	$ 22,049,000	$ 72,395,000	$ 91,363,000	$ 193,930,000	1,121,000	379,737,000	34,547,000
Reportable segments
Segment disclosure
INCOME FROM CONTINUING OPERATIONS BEFORE PROVISION FOR INCOME TAXES									109,457,000	128,452,000	133,406,000
Reconciliation
Segment disclosure
Asset management and other fees to related parties									(22,006,000)	(26,787,000)	(30,327,000)
Interest expense									(26,290,000)	(35,924,000)	(33,848,000)
General and administrative									(4,928,000)	(3,018,000)	(4,231,000)
Transaction costs									(938,000)	(11,862,000)	(340,000)
Depreciation and amortization									(53,228,000)	(58,364,000)	(71,968,000)
Impairment of real estate									0	(13,100,000)	0
Gain on sale of real estate									0	401,737,000	39,666,000
INCOME FROM CONTINUING OPERATIONS BEFORE PROVISION FOR INCOME TAXES									$ 2,067,000	$ 381,134,000	$ 32,358,000