Investments (Tables)

9 Months Ended

Sep. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Schedule of the fair value of cash and cash equivalents and investments

The following table summarizes the fair value of cash and cash equivalents and investments as of December 31, 2017:

							Fair Value
Description	Cost		Level 1		Level 2		(Carrying Value)
Cash
Cash	$	2,544,972	$	2,544,972	$	—	$	2,544,972
Cash equivalents (maturity of 3 months or less)
Repurchase agreements		10,000,000		—		10,000,000		10,000,000
Money market funds		6,014,158		6,014,158		—		6,014,158
Cash and cash equivalents	$	18,559,130	$	8,559,130	$	10,000,000	$	18,559,130
Short-term investments (due within 1 year)
U.S. government treasury obligations	$	63,034,548	$	62,970,115	$	—	$	62,970,115
Corporate obligations		15,942,182		—		15,942,182		15,942,182
Total short-term investments	$	78,976,730	$	62,970,115	$	15,942,182	$	78,912,297

The following table summarizes the fair value of cash and cash equivalents and investments as of September 30, 2018:

							Fair Value
Description	Cost		Level 1		Level 2		(Carrying Value)
Cash
Cash	$	7,280,004	$	7,280,004	$	—	$	7,280,004
Cash equivalents (maturity of 3 months or less)
Repurchase agreements		10,000,000		—		10,000,000		10,000,000
Money market funds		35,004,236		35,004,236		—		35,004,236
U.S. government agency obligations		14,984,175		—		14,984,100		14,984,100
Cash and cash equivalents	$	67,268,415	$	42,284,240	$	24,984,100	$	67,268,340
Short-term investments (due within 1 year)
U.S. government treasury obligations	$	187,315,613	$	187,297,850	$	—	$	187,297,850
Corporate obligations		89,649,086		—		89,644,301		89,644,301
Total short-term investments	$	276,964,699	$	187,297,850	$	89,644,301	$	276,942,151