REAL ESTATE INVESTMENTS - Purchase Price Allocation (Details) - USD ($) $ in Thousands				12 Months Ended
	Dec. 19, 2018	Dec. 11, 2018	Jan. 05, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Mortgage notes payable, net				$ 0	$ 313,812
Repayments of Secured Debt				$ 94,993	$ 7,595	$ 122,180
Quarry Lake II
Business Acquisition [Line Items]
Building, land and improvements	$ 35,120
Intangible assets acquired	5,809
Below market lease liabilities assumed	(1,524)
Deferred gain	0
Total unencumbered acquisition value	39,405
Mortgage debt assumed - at fair value	0
Total encumbered acquisition value	39,405
Mortgage debt repaid at settlement	0
Investment in unconsolidated real estate ventures	0
Gain on promoted interest in unconsolidated real estate venture	0
Gain on real estate venture transactions	0
Purchase price reduction for note receivable	0
Net working capital assumed	(368)
Total cash payment at settlement	$ 39,037
DRA Austin Venture
Business Acquisition [Line Items]
Building, land and improvements		$ 457,390
Intangible assets acquired		76,925
Below market lease liabilities assumed		(13,769)
Deferred gain		14,594
Total unencumbered acquisition value		535,140
Mortgage debt assumed - at fair value		0
Total encumbered acquisition value		535,140
Mortgage debt repaid at settlement		(115,461)
Investment in unconsolidated real estate ventures		(14,594)
Gain on promoted interest in unconsolidated real estate venture		(28,283)
Gain on real estate venture transactions		(103,847)
Purchase price reduction for note receivable		(130,742)
Net working capital assumed		(24,865)
Total cash payment at settlement		$ 117,348
Four Tower Bridge
Business Acquisition [Line Items]
Building, land and improvements			$ 20,734
Intangible assets acquired			3,144
Below market lease liabilities assumed			(182)
Deferred gain			0
Total unencumbered acquisition value			23,696
Mortgage debt assumed - at fair value			(9,940)
Total encumbered acquisition value			13,756
Mortgage debt repaid at settlement			0
Investment in unconsolidated real estate ventures			(3,502)
Gain on promoted interest in unconsolidated real estate venture			0
Gain on real estate venture transactions			(11,633)
Purchase price reduction for note receivable			0
Net working capital assumed			1,379
Total cash payment at settlement			$ 0
Intangible Assets Acquired | Quarry Lake II
Business Acquisition [Line Items]
Weighted average amortization period	0 years
Intangible Assets Acquired | DRA Austin Venture
Business Acquisition [Line Items]
Weighted average amortization period		5 years 6 months
Intangible Assets Acquired | Four Tower Bridge
Business Acquisition [Line Items]
Weighted average amortization period			4 years 1 month 6 days
Below Market Lease | Quarry Lake II
Business Acquisition [Line Items]
Weighted average amortization period	3 years
Below Market Lease | DRA Austin Venture
Business Acquisition [Line Items]
Weighted average amortization period		4 years 7 months 6 days
Below Market Lease | Four Tower Bridge
Business Acquisition [Line Items]
Weighted average amortization period			4 years 9 months 18 days
Mortgage Debt Assumed - at Fair Value
Business Acquisition [Line Items]
Repayments of Secured Debt		$ 115,500
Mortgage Debt Assumed - at Fair Value | Four Tower Bridge
Business Acquisition [Line Items]
Mortgage notes payable, net			$ 9,700