Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Summary of cash equivalents and marketable securities measured at fair value on a recurring basis

The following table summarizes the cash equivalents and marketable securities measured at fair value on a recurring basis as of December 31, 2018 and December 31, 2017:

	Level 1		Level 2		Level 3		Balance at December 31, 2018
Cash equivalents	$	2,333,771	$	—	$	—	$	2,333,771
	$	2,333,771	$	—	$	—	$	2,333,771

	Level 1		Level 2		Level 3		Balance at December 31, 2017
Cash equivalents	$	5,046,205	$	—	$	—	$	5,046,205
Marketable securities:
U.S. government agency securities	—		8,986,259		—		8,986,259
Commercial paper	—		4,440,689		—		4,440,689
Corporate debt securities	—		702,775		—		702,775
	$	5,046,205	$	14,129,723	$	—	$	19,175,928