Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Assets Measured at Fair Value on Recurring Basis

Assets measured at fair value on a recurring basis were as follows:

Description	At March 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents:
Money market funds	$	28,831,110	$	28,831,110	$	—	$	—
Asset-backed securities		2,697,840		—		2,697,840		—
Commercial paper		13,423,213		—		13,423,213		—
Short-term investments:
Asset-backed securities		5,392,684		—		5,392,684		—
Commercial paper		18,854,033		—		18,854,033		—
Corporate debt securities		21,380,024		—		21,380,024		—
U.S. treasury securities		24,892,320		—		24,892,320		—
Total financial assets	$	115,471,224	$	28,831,110	$	86,640,114	$	—
Description	At December 31, 2017		Quoted Prices in Active Markets for Identical Assets(Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents:
Money market funds	$	44,181,756	$	44,181,756	$	—	$	—
Short-term investments:
Asset-backed securities		7,421,703		—		7,421,703		—
Commercial paper		34,882,298		—		34,882,298		—
Corporate debt securities		26,856,283		—		26,856,283		—
U.S. treasury securities		8,923,320		—		8,923,320		—
Total financial assets	$	122,265,360	$	44,181,756	$	78,083,604	$	—

Schedule of Reconciliations of Changes in the Fair Value of Financial Instruments

The reconciliations of changes in the fair value of financial instruments based on Level 3 inputs for the period ended March 31, 2017 consisted of:

Fair value as of January 1, 2017	$	4,247,000
Change in fair value of convertible preferred stock tranche    liability		876,000
Reduction in tranche liability due to preferred stock issuance		(5,123,000	)
Fair value as of March 31, 2017	$	—