REDEEMABLE PREFERRED STOCK - Narrative (Details) - USD ($)		1 Months Ended	9 Months Ended
	Nov. 21, 2017	Oct. 31, 2018	Sep. 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			$ 4,875,000
Non issuance specific costs			4,532,000
Deferred rent receivable reclassified to temporary equity			$ 12,934,000
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			$ 61,276,000
Costs specifically identifiable to the offering			4,793,000
Deferred rent receivable reclassified to temporary equity			$ 312,000
Number of shares redeemed			4,785
Cumulative dividend rate			5.50%
Dividend per share per year (in usd per share)			$ 0.34375
Preferred stock, shares issued (in shares)			1,893,183	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)			2,462,104
Proceeds from issuance of preferred stock and warrants			$ 61,552,000
Warrant
Class of Stock [Line Items]
Net proceeds from issuance of warrants			276,000
Costs specifically identifiable to the offering			82,000
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
Subsequent Event | Series A Preferred Stock
Class of Stock [Line Items]
Number of shares redeemed		200