Nature of Business (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Nature of Business (Textual)
Cash and cash equivalents	$ 6,986,289	$ 4,244,871	$ 6,986,289	$ 4,244,871	$ 8,983,717	$ 7,809,487
Net change in cash and cash equivalent			$ (1,997,428)	(3,564,616)
Percentage change in cash and cash equivalent			22.00%
Cash in operations			$ (2,808,372)	(3,601,092)
Working capital	3,311,412		3,311,412		6,131,178
Change in working capital			$ 2,819,766
Percentage change in working capital			46.00%
Government contract and grant funding available			$ 12,400,000
Accumulated deficit	(169,933,168)		(169,933,168)		$ (166,170,020)
Net loss	$ (2,123,521)	$ (1,556,342)	$ (3,763,148)	$ (3,933,548)
Remaining from FBR sales agreement, description			The Company has up to $6.6 million remaining from the FBR Sales Agreement as of August 8, 2019 under the prospectus supplement updated October 3, 2018.
Contracts from NIH and NIAID, description			The Company is currently developing RiVax® under a NIAID contract of up to $24.7 million over six years, and SGX301 and SGX942 under two separate NIH grants of approximately $1.5 million each over two years.