REDEEMABLE PREFERRED STOCK (Details) - USD ($)					12 Months Ended			18 Months Ended
	Mar. 06, 2018	Jan. 03, 2018	Nov. 21, 2017	Apr. 22, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Nov. 21, 2016
Class of Stock [Line Items]
Class of Warrant or Right, Outstanding (in shares)							0
Deferred offering costs					$ 3,401,000	$ 2,060,000		$ 3,401,000
Offering costs allocated to temporary equity								1,417,000
Redeemable preferred stock dividends accumulated					1,436,000	$ 0	$ 0
Series A Preferred Stock
Class of Stock [Line Items]
Proceeds from issuance of preferred stock					31,998,000
Offering costs					2,499,000
Deferred offering costs					3,527,000			$ 3,527,000
Offering costs allocated to temporary equity					$ 125,000
Preferred stock, shares redeemed (in shares)					1,265	0
Cumulative dividend rate					5.50%
Preferred stock, dividend rate (in usd per share)					$ 0.34375
Preferred stock, shares issued (in shares)					1,225,734	61,435		1,225,734
Preferred stock, par value (in usd per share)					$ 0.001	$ 0.001		$ 0.001	$ 25
Preferred stock, conversion amount per share (in usd per share)					$ 25.00	$ 25.00		$ 25.00
Series A Preferred Unit
Class of Stock [Line Items]
Class of Warrant or Right, Outstanding (in shares)					1,287,169			1,287,169
Proceeds from issuance of preferred stock					$ 32,179,000
Offering costs					2,548,000
Warrant
Class of Stock [Line Items]
Proceeds from issuance of preferred stock					181,000
Offering costs					49,000
Offering costs allocated 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			$ 229,251,000
Preferred stock, shares redeemed (in shares)					0
Cumulative dividend rate					5.50%
Preferred stock, dividend rate (in usd per share)					$ 1.56035
Preferred stock, shares issued (in shares)			8,080,740		8,080,740	0		8,080,740
Preferred stock, par value (in usd per share)					$ 0.001	$ 0		$ 0.001
Preferred stock, conversion amount per share (in usd per share)					$ 28.37	$ 0		$ 28.37
Offering costs			$ 15,928,000
Discount on shares issued			2,946,000
Offering costs, non-issuance specific			$ 2,532,000
Dividend increase per year for failure to timely declare or pay dividends					1.00%
Dividend increase per year for failure to timely declare or pay dividends, maximum increase					8.50%
Minimum fixed charge coverage ratio					125.00%
Registration statement | Series A Preferred Stock
Class of Stock [Line Items]
Maximum amount of offering				$ 900,000,000
Preferred stock, par value (in USD per share)				$ 0.001
Preferred stock stated value (in USD per share)				$ 25.00
Warrant right to purchase a share of Common Stock				0.25
Registration statement | Series A Preferred Unit
Class of Stock [Line Items]
Maximum number of units in offering				36,000,000
Registration statement | Series L Preferred Unit
Class of Stock [Line Items]
Maximum number of units in offering			900,000
Registration statement | Series L Preferred Stock
Class of Stock [Line Items]
Preferred stock, number of shares per unit			10
Preferred stock, par value (in usd per share)			$ 0.001
Preferred stock, conversion amount per share (in usd per share)			$ 28.37
Subsequent event | Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares redeemed (in shares)		600
Preferred stock, dividends per share, declared (in USD per share)	$ 0.34375
Preferred stock, redemption period, year two | Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption fee percentage				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 percentage				10.00%
Preferred stock, redemption period, after year five | Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption fee percentage				0.00%