ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES - Capital Raising Activities (Narrative) (Details) - USD ($)	2 Months Ended	5 Months Ended	7 Months Ended	9 Months Ended		14 Months Ended
	Feb. 20, 2013	Aug. 01, 2017	Feb. 22, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018
Subsidiary, Sale of Stock [Line Items]
Proceeds From Issuance Of Common Stock, net of issuance costs				$ 0	$ 122,857,000
Initial Public Offering [Member]
Subsidiary, Sale of Stock [Line Items]
Stock Issued During Period, Value, New Issues	$ 35,400,000
Total shares issued under distribution agreement	2,400,000
At the Market Offering Program [Member]
Subsidiary, Sale of Stock [Line Items]
Proceeds From Issuance Of Common Stock, net of issuance costs		$ 122,900,000	$ 108,200,000			$ 74,700,000
Stock Issued During Period, Value, New Issues		$ 125,000,000	$ 110,000,000			$ 76,000,000
Total shares issued under distribution agreement		12,299,032	10,174,992			7,746,052
At the Market Offering Program [Member] | Maximum [Member]
Subsidiary, Sale of Stock [Line Items]
Stock Issued During Period, Value, New Issues		$ 125,000,000	$ 125,000,000			$ 125,000,000