STOCKHOLDERS' (DEFICIT) EQUITY - Warrants (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2018
Class of Warrant or Right [Line Items]
Exercise price per warrant (in dollars per share)		$ 1.47	$ 1.20
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)	22,895
Warrants Issued (in shares)	0
Warrants Exercised (in shares)	(238)
Warrants Cancelled (in shares)	(20,410)
Warrants outstanding, ending balance (in shares)	2,247
Warrants, Expiring June 2020
Class of Warrant or Right [Line Items]
Exercise price per warrant (in dollars per share)	$ 1.47
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)	20,410
Warrants Issued (in shares)	0
Warrants Exercised (in shares)	0
Warrants Cancelled (in shares)	(20,410)
Warrants outstanding, ending balance (in shares)	0
Warrants, Expiring March 2023
Class of Warrant or Right [Line Items]
Exercise price per warrant (in dollars per share)	$ 0.55
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)	1,943
Warrants Issued (in shares)	0
Warrants Exercised (in shares)	(238)
Warrants Cancelled (in shares)	0
Warrants outstanding, ending balance (in shares)	1,705
Warrants, Expiring November 2022
Class of Warrant or Right [Line Items]
Exercise price per warrant (in dollars per share)	$ 0.55
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)	487
Warrants Issued (in shares)	0
Warrants Exercised (in shares)	0
Warrants Cancelled (in shares)	0
Warrants outstanding, ending balance (in shares)	487
Warrants, Expiring November 2024, Issued May 2015
Class of Warrant or Right [Line Items]
Exercise price per warrant (in dollars per share)	$ 11.83
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)	28
Warrants Issued (in shares)	0
Warrants Exercised (in shares)	0
Warrants Cancelled (in shares)	0
Warrants outstanding, ending balance (in shares)	28
Warrants, Expiring November 2024, Issued November 2014
Class of Warrant or Right [Line Items]
Exercise price per warrant (in dollars per share)	$ 11.04
Warrant Or Right Outstanding [Roll Forward]
Warrants outstanding, beginning balance (in shares)	27
Warrants Issued (in shares)	0
Warrants Exercised (in shares)	0
Warrants Cancelled (in shares)	0
Warrants outstanding, ending balance (in shares)	27