EQUITY STRUCTURE AND ACCOUNTS - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	$ 1,643,635	[1]	$ 1,488,146		$ 1,509,554
Other comprehensive income (loss)	9,930		(5,141)		(2,220)
Exchange of noncontrolling interest for common stock	0		0		0
Rebalancing of ownership percentage between Company and Operating Partnership	0		0		0
Ending Balance	1,638,977	[1]	1,643,635	[1]	1,488,146
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	(4,649)		(212)		1,365
Other comprehensive income (loss)	8,785		(4,211)		(2,915)
Exchange of noncontrolling interest for common stock	65		(167)		1,696
Rebalancing of ownership percentage between Company and Operating Partnership	17		(59)		(358)
Ending Balance	4,218		(4,649)		(212)
Accumulated Other Comprehensive Income (Loss) of Noncontrolling Interests
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	(588)		116		759
Other comprehensive income (loss)	1,145		(930)		695
Exchange of noncontrolling interest for common stock	(65)		167		(1,696)
Rebalancing of ownership percentage between Company and Operating Partnership	(17)		59		358
Ending Balance	475		(588)		116
Total Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent [Roll Forward]
Beginning Balance	(5,237)		(96)		2,124
Ending Balance	$ 4,693		$ (5,237)		$ (96)

[1] Includes amounts relating to consolidated variable interest entities. See Note 10.