SEGMENT DISCLOSURE - Results of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment disclosure
Asset management and other fees to related parties									$ (30,251)	$ (33,882)	$ (33,169)
Interest expense									(36,338)	(34,385)	(23,630)
General and administrative									(5,479)	(7,961)	(9,402)
Transaction costs									(11,862)	(340)	(1,382)
Depreciation and amortization									(58,364)	(71,968)	(72,361)
Impairment of real estate									(13,100)	0	0
Gain on sale of real estate	$ 23,005	$ 74,715	$ 116,283	$ 187,734	$ 0	$ 14,927	$ 0	$ 24,739	401,737	39,666	3,092
Provision for income taxes									(1,376)	(1,646)	(806)
Net income from continuing operations	22,060	72,391	91,372	193,935	(3,153)	8,382	(810)	26,293	379,758	30,712	6,112
Discontinued operations:
Income from operations of assets held for sale (Note 7)									0	3,853	13,140
Gain on disposition of assets held for sale									0	0	5,151
NET INCOME FROM DISCONTINUED OPERATIONS					792	703	1,668	690	0	3,853	18,291
NET INCOME	22,060	72,391	91,372	193,935	(2,361)	9,085	858	26,983	379,758	34,565	24,403
Net income attributable to noncontrolling interests									(21)	(18)	(11)
NET INCOME ATTRIBUTABLE TO THE COMPANY	$ 22,049	$ 72,395	$ 91,363	$ 193,930	$ (2,370)	$ 9,088	$ 849	$ 26,980	379,737	34,547	24,392
Reportable segments
Segment disclosure
INCOME FROM CONTINUING OPERATIONS BEFORE PROVISION FOR INCOME TAXES									128,452	133,406	136,294
Reconciliation
Segment disclosure
Asset management and other fees to related parties									(26,787)	(30,327)	(29,319)
Interest expense									(35,924)	(33,848)	(22,785)
General and administrative									(3,018)	(4,231)	(6,621)
Transaction costs									(11,862)	(340)	(1,382)
Depreciation and amortization									(58,364)	(71,968)	(72,361)
Impairment of real estate									(13,100)	0	0
Gain on sale of real estate									401,737	39,666	3,092
INCOME FROM CONTINUING OPERATIONS BEFORE PROVISION FOR INCOME TAXES									$ 381,134	$ 32,358	$ 6,918