Quarterly Results of Operations - Summarized Unaudited Quarterly Financial Data (Details) - USD ($)	3 Months Ended								12 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2014
Consolidated Statements of Comprehensive Loss Data:
Revenues	$ 932,000	$ 899,000	$ 671,000	$ 731,000	$ 2,395,000	$ 1,183,000	$ 1,003,000	$ 1,072,000	$ 3,233,247	$ 5,653,091	$ 9,041,605
Net loss attributable to Immunomedics, Inc. stockholders	$ (15,901,000)	$ (13,996,000)	$ (13,746,000)	$ (15,394,000)	$ (12,401,000)	$ (11,756,000)	$ (11,435,000)	$ (12,410,000)	$ (59,036,950)	$ (48,002,366)	$ (35,425,826)
Loss per common share attributable to Immunomedics Inc. stockholders – (basic and diluted)	$ (0.16)	$ (0.15)	$ (0.15)	$ (0.16)	$ (0.13)	$ (0.13)	$ (0.12)	$ (0.13)	$ (0.62)	$ (0.51)	$ (0.42)
Weighted average shares used to calculate loss per common share – (basic and diluted	94,770,000	94,748,000	94,665,000	94,596,000	93,657,000	93,352,000	93,157,000	93,098,000	94,770,172	93,314,872	84,631,567