Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2016

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, 2016 and December 31, 2015:

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

	Level 1		Level 2		Level 3		Balance as of December 31, 2015
Cash equivalents	$	58,575,348	$	1,410,322	$	—	$	59,985,670
Marketable securities:
Corporate debt securities	—		26,965,297		—		26,965,297
	$	58,575,348	$	28,375,619	$	—	$	86,950,967