REDEEMABLE PREFERRED STOCK - Narrative (Details) - USD ($)					3 Months Ended
	Feb. 20, 2019	Mar. 06, 2018	Nov. 21, 2017	Jul. 01, 2016	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Class of Stock [Line Items]
Preferred stock redemption, trading days prior to redemption					20 days
Costs specifically identifiable to the offering					$ 6,260,000
Non issuance specific costs					4,809,000
Deferred rent receivable reclassified to temporary equity					38,194,000
Aggregate dividends declared					1,010,000	$ 493,000
Accumulated cash dividends					$ 4,162,000	3,645,000
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock redemption, trading days prior to redemption					20 days
Proceeds from issuance of preferred stock					$ 78,659,000
Costs specifically identifiable to the offering					6,157,000
Deferred rent receivable reclassified to temporary equity					$ 398,000
Number of shares redeemed					9,105
Cumulative dividend rate					5.50%
Dividend per share per year (in usd per share)					$ 0.34375
Preferred stock, shares issued (in shares)					1,481,243		1,566,386
Preferred stock, liquidation preference per share (in usd per share)					$ 25.00		$ 25.00
Aggregate dividends declared	$ 1,010,000	$ 493,000
Series A Preferred Unit
Class of Stock [Line Items]
Units issued (in shares)					3,159,029
Proceeds from issuance of preferred stock and warrants					$ 78,976,000
Warrant
Class of Stock [Line Items]
Net proceeds from issuance of warrants					317,000
Costs specifically identifiable to the offering					103,000
Deferred rent receivable reclassified to temporary equity					$ 1,000
Series L Preferred Stock
Class of Stock [Line Items]
Proceeds from issuance of preferred stock and warrants			$ 229,251,000
Costs specifically identifiable to the offering			15,928,000
Non issuance specific costs			$ 2,532,000
Number of shares redeemed					0
Cumulative dividend rate					5.50%
Dividend per share per year (in usd per share)					$ 1.56035
Preferred stock, shares issued (in shares)			8,080,740		8,080,740		8,080,740
Preferred stock, liquidation preference per share (in usd per share)					$ 28.37		$ 28.37
Preferred stock discount			$ 2,946,000
Failure to declare or pay distributions, temporary increase per year					1.00%
Failure to declare or pay distributions, temporary increase per year, maximum increase					8.50%
Accumulated cash dividends					$ 3,152,000	$ 3,152,000
Minimum Fixed Charge Coverage Ratio					125.00%
Registration Statement
Class of Stock [Line Items]
Maximum amount of offering					$ 900,000,000
Warrant right to purchase a share of common stock (in shares)					0.25
Maximum number of units in offering (in shares)					36,000,000
Registration Statement | Series A Preferred Stock
Class of Stock [Line Items]
Redeemable preferred stock, par value (in usd per share)					$ 0.001
Preferred stock, stated value (in usd per share)					$ 25
Registration Statement | Series L Preferred Stock
Class of Stock [Line Items]
Preferred stock, liquidation preference per share (in usd per share)			$ 28.37
Preferred Stock, Redemption Period, Year Two | Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption fee				13.00%
Preferred Stock, Redemption Period, After Year Two, Before Year Five | Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption fee				10.00%
Preferred Stock, Redemption Period, After Year Five | Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption fee				0.00%