Cash, Cash Equivalents and Short-Term Investments (Tables)

3 Months Ended

Mar. 31, 2019

Cash And Cash Equivalents [Abstract]

Schedule of Cash and Cash Equivalents and Short-Term Investments by Significant Investment Category

The following tables show the Company’s cash and cash equivalents and short-term investments by significant investment category as of March 31, 2019 and December 31, 2018:

	March 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value		Cash and Cash Equivalents		Short-Term Investments
Cash	$	3,979,962	$	—	$	—		$	3,979,962	$	3,979,962	$	—

Level 1 (1):
Money market funds		4,766,828		—		—			4,766,828		4,766,828		—
U.S. treasury securities		4,976,466		1,209		—			4,977,675		—		4,977,675
Subtotal		9,743,294		1,209		—			9,744,503		4,766,828		4,977,675
Level 2 (2):
Commercial paper		8,065,664		—		—			8,065,664		—		8,065,664
Corporate debt obligations		3,701,311		616		(143	)		3,701,784		—		3,701,784
Repurchase agreements		3,000,630		—		—			3,000,630		3,000,630		—
Asset-backed securities		4,390,774		2,092		(362	)		4,392,504		—		4,392,504
Subtotal		19,158,379		2,708		(505	)		19,160,582		3,000,630		16,159,952

Total	$	32,881,635	$	3,917	$	(505	)	$	32,885,047	$	11,747,420	$	21,137,627

	December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value		Cash and Cash Equivalents		Short-Term Investments
Cash	$	3,043,800	$	—	$	—		$	3,043,800	$	3,043,800	$	—

Level 1 (1):
Money market funds		5,481,647		—		—			5,481,647		5,481,647		—
U.S. treasury securities		1,987,794		—		(164	)		1,987,630		—		1,987,630
Subtotal		7,469,441		—		(164	)		7,469,277		5,481,647		1,987,630
Level 2 (2):
Commercial paper		10,639,390		—		—			10,639,390		2,094,983		8,544,407
Corporate debt obligations		5,963,913		—		(6,678	)		5,957,235		—		5,957,235
Repurchase agreements		3,000,226		—		—			3,000,226		3,000,226		—
Asset-backed securities		3,682,413		250		(2,954	)		3,679,709		—		3,679,709
Subtotal		23,285,942		250		(9,632	)		23,276,560		5,095,209		18,181,351

Total	$	33,799,183	$	250	$	(9,796	)	$	33,789,637	$	13,620,656	$	20,168,981

(1)

Level 1 fair value estimates are based on quoted prices in active markets for identical assets or liabilities.

(2)

Level 2 fair value estimates are based on observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Summary of Short-term Investments with Unrealized Losses

The following table presents the Company’s short-term investments with unrealized losses by investment category and length of time that individual securities have been in a continuous unrealized loss position as of March 31, 2019:

	Less Than 12 Months
Description of Securities	Estimated Fair Value		Unrealized Losses

Corporate debt obligations	$	1,492,290	$	(143	)
Asset-backed securities		749,732		(362	)
Total	$	2,242,022	$	(505	)

Schedule of Contractual Maturities of Short-term Investments

Contractual maturities of short-term investments as of March 31, 2019 are as follows:

	Estimated Fair Value
Due within one year	$	21,137,627
Total	$	21,137,627