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SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) - USD ($)					1 Months Ended			3 Months Ended				12 Months Ended
	Feb. 17, 2021	Oct. 01, 2020	Sep. 14, 2020	Mar. 18, 2020	Jul. 23, 2018	Oct. 19, 2017	Oct. 31, 2015	Mar. 31, 2021	Mar. 30, 2021	Dec. 31, 2020	Sep. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Significant Accounting Policies [Line Items]
Common Stock, Par or Stated Value Per Share (in dollars per share)										$ 0.001		$ 0.001	$ 0.001
Gross proceeds												$ 4,867,000
Exercise price of warrants (in dollars per share)										$ 2.36		$ 2.36
Proceeds from private placement				$ 41,300,000
Notes Payable, Current										$ 4,086,000		$ 4,086,000	$ 4,301,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount												22,850,682	7,838,120	7,458,380
Rental expense														$ 1,400,000
Operating Lease, Right-of-Use Asset										5,567,000		$ 5,567,000	$ 5,677,000
Operating Lease, Liability										$ 5,887,000		$ 5,887,000	$ 5,700,000
Incremental average borrowing rate at inception												12.58%
Subsequent Event [Member]
Significant Accounting Policies [Line Items]
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001
Shares Issued, Price Per Share	4.60
Share price	$ 4.60
Gross proceeds	$ 40,200,000								$ 8,800,000
Number of shares issued (in shares)	8,749,999								1,867,552
Seven Point Five Percentage Convertible Notes [Member]
Significant Accounting Policies [Line Items]
Interest rate (as a percent)										7.50%		7.50%
Notes Payable, Current										$ 57,900,000		$ 57,900,000
2018 Notes [Member]
Significant Accounting Policies [Line Items]
Notes Payable, Current										$ 0		$ 0
Term of debt														5 years
Minimum [Member]
Significant Accounting Policies [Line Items]
Tax Rate Assumption Related To Deferred Tax Difference Reversal										23.00%		23.00%
Maximum [Member]
Significant Accounting Policies [Line Items]
Tax Rate Assumption Related To Deferred Tax Difference Reversal										26.00%		26.00%
Amended Pfizer Agreement [Member] \| Protalix Bio Therapeutics Incorporation [Member] \| Brazil [Member]
Significant Accounting Policies [Line Items]
Collaborative Arrangement Revenues Expenses Sharing Percentage							100.00%
Chiesi US Agreement and Chiesi Ex US Agreement [Member]
Significant Accounting Policies [Line Items]
Upfront Nonrefundable Non-Creditable Payment Receivable						$ 25,000,000.0				$ 50,000,000.0		$ 50,000,000.0
Chiesi US Agreement [Member]
Significant Accounting Policies [Line Items]
Upfront Nonrefundable Non-Creditable Payment Receivable					$ 25,000,000.0	25,000,000.0
Additional Amounts Payable To Cover Development Costs					20,000,000.0
Additional Amount Payable For Achievement Of Regulatory And Commercial Milestones					$ 760,000,000.0					760,000,000.0		$ 760,000,000.0
Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Modification of Contract											$ 6,200,000
Chiesi US Agreement [Member] \| Minimum [Member]
Significant Accounting Policies [Line Items]
Payment On Net Sales Percentage					15.00%							15.00%
Chiesi US Agreement [Member] \| Maximum [Member]
Significant Accounting Policies [Line Items]
Payment On Net Sales Percentage					40.00%							40.00%
Chiesi Ex US Agreement [Member]
Significant Accounting Policies [Line Items]
Upfront Nonrefundable Non-Creditable Payment Receivable						25,000,000.0
Additional Amounts Payable To Cover Development Costs						25,000,000.0
Additional Amount Payable For Achievement Of Regulatory And Commercial Milestones						$ 320,000,000.0				320,000,000.0		$ 320,000,000.0
Chiesi Ex US Agreement [Member] \| Minimum [Member]
Significant Accounting Policies [Line Items]
Payment On Net Sales Percentage						15.00%						15.00%
Chiesi Ex US Agreement [Member] \| Maximum [Member]
Significant Accounting Policies [Line Items]
Payment On Net Sales Percentage						35.00%						35.00%
ATM Shares
Significant Accounting Policies [Line Items]
Gross proceeds										$ 5,000,000		$ 5,000,000.0
Sale Of Stock Maximum Offering Price		$ 30,000,000
Number of shares issued (in shares)										1,428,571		1,428,571
ATM Shares \| Subsequent Event [Member]
Significant Accounting Policies [Line Items]
Gross proceeds								$ 8,800,000
Number of shares issued (in shares)								1,867,552
Private Placement [Member]
Significant Accounting Policies [Line Items]
Share price				$ 2.485
Number of shares issued (in shares)			200,000	17,604,423
Purchase price (in dollars per share)				$ 2.485
Number of warrants issued (in shares)				17,604,423
Exercise price of warrants (in dollars per share)				$ 2.36
Exercise of warrants, commencement period				6 months
Term of warrants				5 years
Proceeds from private placement				$ 43,700,000