Cellectar Biosciences, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

STOCKHOLDERS' EQUITY - Additional Information (Details)

STOCKHOLDERS' EQUITY - Additional Information (Details)					3 Months Ended
STOCKHOLDERS' EQUITY - Additional Information (Details)	Mar. 31, 2021 USD ($) $ / shares shares	Dec. 28, 2020 USD ($)	Dec. 23, 2020 $ / shares shares	Jun. 05, 2020 USD ($) $ / shares shares	Mar. 31, 2021 USD ($) $ / shares shares	Feb. 25, 2021 shares	Feb. 24, 2021 shares	Dec. 31, 2020 USD ($) $ / shares shares	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	16,450,946				16,450,946
Common Stock, Shares Authorized	160,000,000				160,000,000	160,000,000	80,000,000	80,000,000
Common Stock, Par or Stated Value Per Share \| $ / shares	$ 0.00001				$ 0.00001			$ 0.00001
Stockholders' Equity Attributable to Parent \| $	$ 49,775,847				$ 49,775,847			$ 54,794,529	$ 5,245,947	$ 9,059,409
June 2020 Pre Funded Warrants [Member]
Class of Warrant or Right [Line Items]
Stock Issued During Period, Shares, New Issues				14,601,628
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				2,789,700
Number of warrants exercised					2,789,700
Number of share of common stock per warrant				1
Exercise price of warrants (in dollars per share) \| $ / shares				$ 0.00001
June 2020 Series H Warrants [Member]
Class of Warrant or Right [Line Items]
Issuance of common stock, warrants and preferred stock, net of issuance costs \| $				$ 20,000,000
Proceeds from issuance of common stock and warrants, net of underwriting issuance costs \| $				12,100,000
Proceeds from warrants \| $				7,900,000
Net proceeds from stockholders' equity \| $				$ 18,300,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				8,695,664
Warrants and Rights Outstanding, Term				5 years
Number of warrants exercised	1,487,695				1,005,320
Stockholders' Equity Attributable to Parent \| $				$ 20,000,000
Public Offering Price Of Share And Warrants \| $ / shares				$ 1.15
Public Offering Price Of Warrants \| $ / shares				1.1499
Exercise price of warrants (in dollars per share) \| $ / shares				$ 1.2075
Series D Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Stock Issued During Period, Shares, New Issues			1,518.518
Number of shares converted					574.0736
Number of shares issued upon conversion					5,740,736
Private Placement [Member] \| Series D Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Stock Issued During Period, Shares, New Issues			10,000
Convertible Preferred Stock, Shares Issued upon Conversion			13,500
Convertible Preferred Stock Conversion Price \| $ / shares			$ 1.35
Private Placement [Member] \| December 2020 Public Offering and Private Placement
Class of Warrant or Right [Line Items]
Stock Issued During Period, Shares, New Issues			18,148,136
Proceeds from issuance of preferred stock \| $		$ 20,500,000
Issuance of common stock, warrants and preferred stock, net of issuance costs \| $		45,000,000
Proceeds from issuance of common stock and warrants, net of underwriting issuance costs \| $		$ 24,500,000
Net proceeds from stockholders' equity \| $					$ 41,400,000
Common Stock, Par or Stated Value Per Share \| $ / shares			$ 0.00001
Public offering price of share \| $ / shares			$ 1.35
Minimum [Member] \| Series D Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Conversion rate					1
Maximum [Member] \| Series D Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Conversion rate					10,000