REDEEMABLE PREFERRED STOCK - Narrative (Details) - USD ($)		6 Months Ended
	Nov. 21, 2017	Jun. 30, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Preferred stock redemption, trading days prior to redemption		20 days
Costs specifically identifiable to the offering		$ 4,262,000
Non issuance specific costs		4,451,000
Deferred rent receivable reclassified to temporary equity		$ 7,032,000
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		$ 53,613,000
Costs specifically identifiable to the offering		4,191,000
Deferred rent receivable reclassified to temporary equity		$ 265,000
Number of shares redeemed		4,385
Cumulative dividend rate		5.50%
Dividend per share per year (in usd per share)		$ 0.34375
Preferred stock, shares issued (in shares)		1,845,473	1,225,734
Preferred stock, liquidation preference per share (in usd per share)		$ 25.00	$ 25.00
Series A Preferred Unit
Class of Stock [Line Items]
Units issued (in shares)		2,154,248
Proceeds from issuance of preferred stock and warrants		$ 53,856,000
Warrant
Class of Stock [Line Items]
Net proceeds from issuance of warrants		243,000
Costs specifically identifiable to the offering		71,000
Deferred rent receivable reclassified to temporary equity		$ 1,000
Series L Preferred Unit
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	808,074
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%
Minimum Fixed Charge Coverage Ratio		125.00%
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%
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]
Number of shares per unit	10
Preferred stock, liquidation preference per share (in usd per share)	$ 28.37