STOCKHOLDERS' EQUITY (Common Stock, 2018 Purchase Agreement and LP Purchase Agreement) (Details)										1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended		30 Months Ended
	Jun. 26, 2020 shares	May 13, 2020 USD ($) shares	Apr. 08, 2020 shares	Mar. 26, 2020 USD ($) D $ / shares shares	Jan. 14, 2020 shares	Aug. 09, 2019 shares	Feb. 01, 2019 shares	Sep. 14, 2018 shares	Sep. 07, 2018 USD ($) $ / shares shares	Apr. 30, 2020	Jun. 30, 2020 USD ($) shares	Jun. 30, 2019 USD ($) shares	Jun. 30, 2020 USD ($) shares	Jun. 30, 2019 USD ($) shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Jun. 30, 2020 USD ($) shares	Apr. 06, 2020 shares	Jan. 29, 2019 USD ($)	Jan. 01, 2019 shares	Dec. 20, 2018 shares	Sep. 06, 2018 shares
Class of Stock [Line Items]
Common stock, shares authorized (in shares)											150,000,000		150,000,000		150,000,000		150,000,000			250,000,000	150,000,000
Common stock, shares outstanding (in shares)				8,870,129							14,616,916		14,616,916		7,898,117		14,616,916					1,543,724
Shares sold in offering (in shares)		1,810,000
Issuance of common stock, net of issuance costs | $													$ 2,607,000	$ 2,410,000
Conversion of interest on convertible debt into common stock | $													1,938,000	7,272,000
Conversion of debt into stock | $													$ 1,938,000	7,272,000
Proceeds from exercise of warrants | $														$ 1,575,000
Shares issued (in shares)											14,616,916		14,616,916		7,898,117		14,616,916
Common Stock
Class of Stock [Line Items]
Conversion of convertible notes into common stock (in shares)											3,480,148	1,138,310	3,908,145	2,386,425
Common stock issued in connection with the conversion of convertible notes											3,480,148		3,908,145
Conversion of interest on convertible debt into common stock | $											$ 1,800,000	$ 4,100,000	$ 2,200,000	$ 7,300,000
Number of shares converted from debt instrument (in shares)											3,480,148	1,138,310	3,908,145	2,386,425
Conversion of debt into stock | $											$ 1,800,000	$ 4,100,000	$ 2,200,000	$ 7,300,000
Preferred Class B
Class of Stock [Line Items]
Number of shares converted (in shares)											0	0	0	0
Leviston Resources LLC
Class of Stock [Line Items]
Conversion of convertible notes into common stock (in shares)												111,023		184,357
Conversion of interest on convertible debt into common stock | $												$ 500,000		$ 700,000
Number of shares converted from debt instrument (in shares)												111,023		184,357
Conversion of debt into stock | $												$ 500,000		$ 700,000
Leviston Resources LLC | Settled Litigation
Class of Stock [Line Items]
Issuance of convertible notes | $																			$ 700,000
Lincoln Park [Member]
Class of Stock [Line Items]
New shares issued (in shares)	4,500,000				920,654	1,800,000	1,000,000	466,667	40,000
Value of shares issued | $									$ 10,000,000
Maximum percentage of shares issued									19.99%
Maximum number of shares issued									308,590
Beneficial Ownership Cap									4.99%
Shares sold in offering (in shares)		3,330,000									110,642		1,040,654		2,778,077	328,590
Issuance of common stock, net of issuance costs | $		$ 3,700,000									$ 100,000		$ 1,400,000		$ 6,600,000	$ 1,400,000	$ 9,400,000
Share price (in dollars per share) | $ / shares									$ 7.05
Shares issued (in shares)																		920,654
Minimum | Lincoln Park [Member]
Class of Stock [Line Items]
Share price (in dollars per share) | $ / shares				$ 1.50					$ 1.50
Maximum | Lincoln Park [Member]
Class of Stock [Line Items]
Value of shares issued | $									$ 1,000,000				10,000,000
Shares sold in offering based on market price									36,666
Shares sold in offering (in shares)									30,000
LP 2020 Purchase Agreement [Member]
Class of Stock [Line Items]
Issuance of common stock, net of issuance costs | $													$ 4,900,000
LP 2020 Purchase Agreement [Member] | Lincoln Park [Member]
Class of Stock [Line Items]
New shares issued (in shares)			1,770,000	250,000
Value of shares issued | $				$ 10,000,000
Maximum percentage of shares issued				19.99%
Maximum number of shares issued				1,774,024
Beneficial Ownership Cap										4.99%
Shares sold in offering (in shares)													1,520,000
Issuance of common stock, net of issuance costs | $													$ 1,200,000
Share price (in dollars per share) | $ / shares				$ 0.7306
Number of business days prior to purchase date | D				10
LP 2020 Purchase Agreement [Member] | Minimum | Lincoln Park [Member]
Class of Stock [Line Items]
Share price (in dollars per share) | $ / shares				$ 1.00
LP 2020 Purchase Agreement [Member] | Maximum | Lincoln Park [Member]
Class of Stock [Line Items]
Value of shares issued | $				$ 1,000,000
Shares sold in offering based on market price				50,000
LP 2020 Purchase Agreement [Member] | Closing Sale Price Above 1.00 [Member] | Maximum
Class of Stock [Line Items]
Shares sold in offering based on market price				80,000
LP 2020 Purchase Agreement [Member] | Closing Sale Price Above 1.50 [Member] | Maximum | Lincoln Park [Member]
Class of Stock [Line Items]
Shares sold in offering based on market price				100,000