EQUITY STRUCTURE AND ACCOUNTS - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
AOCI Attributable to Parent [Roll Forward]
December 31, 2015			$ (3,556)
Other comprehensive income (loss)	$ (8,576)	$ 15,992	53,275	$ (4,119)	$ (36,545)
Exchange of noncontrolling interest for common stock			(1,412)		0
September 30, 2016	27,893		27,893		(3,556)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent [Roll Forward]
December 31, 2015			(3,556)
Other comprehensive income (loss)			30,171		(20,046)
Exchange of noncontrolling interest for common stock			928		645
Rebalancing of ownership percentage between Company and Operating Partnership			350
September 30, 2016	27,893		27,893		(3,556)
Accumulated Other Comprehensive Income of Noncontrolling Interests
AOCI Attributable to Parent [Roll Forward]
December 31, 2015			(2,839)
Other comprehensive income (loss)			23,104
Exchange of noncontrolling interest for common stock			(928)
Rebalancing of ownership percentage between Company and Operating Partnership			(350)
September 30, 2016	18,987		18,987		(2,839)
Total Accumulated Other Comprehensive Income
AOCI Attributable to Parent [Roll Forward]
December 31, 2015			(6,395)
Other comprehensive income (loss)			53,275
Exchange of noncontrolling interest for common stock			0
Rebalancing of ownership percentage between Company and Operating Partnership			0
September 30, 2016	$ 46,880		$ 46,880		$ (6,395)