CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Total revenues	$ 0	$ 0
Costs and Expenses:
Research and development	62,428	58,172
Sales and marketing	8,067	7,881
General and administrative	11,473	13,595
Total costs and expenses	81,968	79,648
Operating loss	(81,968)	(79,648)
Interest expense	(13,538)	(9,959)
Interest and other income	2,427	2,203
Loss before income tax	(93,079)	(87,404)
Income tax expense	0	0
Net loss	(93,079)	(87,404)
Net loss attributable to noncontrolling interest	(32)	(67)
Net loss attributable to Immunomedics, Inc. stockholders	$ (93,047)	$ (87,337)
Loss per common share attributable to Immunomedics, Inc. stockholders (basic and diluted) (in usd per share)	$ (0.44)	$ (0.46)
Weighted average shares used to calculated loss per common share (basic and diluted) (in shares)	213,247	191,052
Other comprehensive loss, net of tax:
Foreign currency translation adjustments	$ (9)	$ (9)
Unrealized loss on securities available for sale	(225)	(200)
Other comprehensive loss, net of tax:	(234)	(209)
Comprehensive loss	(93,313)	(87,613)
Comprehensive loss attributable to noncontrolling interest	(32)	(67)
Comprehensive loss attributable to Immunomedics, Inc. stockholders	$ (93,281)	$ (87,546)