Nature of Operations and Basis of Presentation - Schedule of Effect of Error Correction on Previously Issued Financial Statements (Details) - USD ($)	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Changes in the balance sheet:
Deferred collaboration funding, short-term	$ 22,191,292				$ 22,191,292
Total current liabilities	35,147,054				35,147,054		$ 6,145,546
Total liabilities	35,147,054				35,147,054		6,389,354
Accumulated deficit	(106,816,303)				(106,816,303)		(99,135,961)
Total stockholders' equity	4,837,138	$ 7,311,512	$ 11,218,371	$ 14,088,948	4,837,138	$ 11,218,371	$ 8,224,334	$ 18,370,316
Changes in the statement of operations:
Revenue					900,000
Research and development	1,361,287		2,816,749		3,367,192	5,139,653
General and administrative	2,268,508		2,953,137		5,782,649	5,601,688
Total operating expenses	3,629,795		5,769,886		9,149,841	10,741,341
Loss from operations	(3,629,795)		(5,769,886)		(8,249,841)	(10,741,341)
Net loss	$ (3,069,037)	$ (4,611,305)	$ (5,770,801)	$ (4,948,707)	$ (7,680,342)	$ (10,719,507)
Net loss per share - basic and diluted	$ (0.21)		$ (0.56)		$ (0.54)	$ (1.05)
Research and development collaboration funding offset	$ 1,025,935				$ 1,312,038
General and administrative collaboration funding offset	602,534				602,534
Changes in the statement of cash flows:
Net loss					(7,680,342)	$ (10,719,507)
Deferred collaboration funding, short-term					18,191,292
As Previously Reported
Changes in the balance sheet:
Deferred collaboration funding, short-term	19,251,394				19,251,394
Total current liabilities	32,207,156				32,207,156
Total liabilities	32,207,156				32,207,156
Accumulated deficit	(103,876,405)				(103,876,405)
Total stockholders' equity	7,777,036				7,777,036
Changes in the statement of operations:
Revenue					3,998,133
Research and development	1,460,975				3,466,880
General and administrative	2,327,055				5,841,196
Total operating expenses	3,788,030				9,308,076
Loss from operations	(3,788,030)				(5,309,943)
Net loss	$ (3,227,272)				$ (4,740,444)
Net loss per share - basic and diluted	$ (0.23)				$ (0.33)
Research and development collaboration funding offset	$ 926,247				$ 1,212,350
General and administrative collaboration funding offset	543,987				543,987
Changes in the statement of cash flows:
Net loss					(4,740,444)
Deferred collaboration funding, short-term					15,251,394
Correction of Error
Changes in the balance sheet:
Deferred collaboration funding, short-term	2,939,898				2,939,898
Total current liabilities	2,939,898				2,939,898
Total liabilities	2,939,898				2,939,898
Accumulated deficit	(2,939,898)				(2,939,898)
Total stockholders' equity	(2,939,898)				(2,939,898)
Changes in the statement of operations:
Revenue					(3,098,133)
Research and development	(99,688)				(99,688)
General and administrative	(58,547)				(58,547)
Total operating expenses	(158,235)				(158,235)
Loss from operations	158,235				(2,939,898)
Net loss	$ 158,235				$ (2,939,898)
Net loss per share - basic and diluted	$ 0.02				$ (0.21)
Research and development collaboration funding offset	$ 99,688				$ 99,688
General and administrative collaboration funding offset	$ 58,547				58,547
Changes in the statement of cash flows:
Net loss					(2,939,898)
Deferred collaboration funding, short-term					$ 2,939,898