STOCKHOLDERS' EQUITY - Preferred Stock and Non-Cash Preferred Stock Dividend (Details) - USD ($) $ / shares in Units, $ in Millions						6 Months Ended
	Oct. 08, 2019	Feb. 09, 2018	Apr. 06, 2017	Feb. 27, 2017	Jan. 24, 2017	Jun. 30, 2017	Dec. 31, 2019	Oct. 02, 2019	Dec. 31, 2018	Mar. 16, 2017
Stockholders' equity
Shares issued	16,200,000	9,200,000	55,200,000
Share price (in dollars per share)		$ 6.90						$ 19.74
Par value of common stock (in dollars per share)	$ 0.0001	$ 0.0001					$ 0.0001		$ 0.0001
8% Convertible Preferred Stock
Stockholders' equity
Shares issued					5,518
Dividend rate (as a percent)					8.00%
Preferred stock, par value (in dollars per share)					$ 0.0001
Number of shares of common stock to be issued upon conversion					10,000
Proceeds from issuance of convertible preferred stock per share				$ 72,500
Gross proceeds from preferred stock offering				$ 400.1
Share price (in dollars per share)				$ 7.25	$ 8.12
Offering costs including placement agent fees				$ 11.9
Par value of common stock (in dollars per share)										$ 0.0001
Preferred dividend						$ 0.0
Conversion price (in dollars per share)					$ 0.87
Beneficial conversion proceeds					$ 48.0
Discount amortization period					65 months