Fair value measurements (Tables)

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Summary of Cash Equivalents and Marketable Securities Measured at Fair Value on a Recurring Basis

The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis as of June 30, 2017 and December 31, 2016:

	Level 1		Level 2		Level 3		Balance as of June 30, 2017
Cash equivalents	$	26,029,665	$	—	$	—	$	26,029,665
Marketable securities:
U.S. government agency securities	—		7,996,199		—		7,996,199
	$	26,029,665	$	7,996,199	$	—	$	34,025,864

	Level 1		Level 2		Level 3		Balance as of December 31, 2016
Cash equivalents	$	11,681,074	$	—	$	—	$	11,681,074
Marketable securities:
U.S. government agency securities	—		31,059,491		—		31,059,491
Commercial paper	—		6,081,202		—		6,081,202
Corporate debt securities	—		1,518,240		—		1,518,240
	$	11,681,074	$	38,658,933	$	—	$	50,340,007