Cash equivalents and marketable securities (Details)	12 Months Ended
Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) security
Cash and Cash Equivalents [Abstract]
Realized gains on marketable securities	$ 0	$ 0
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		14,130,970
Unrealized Gains		38
Unrealized Losses		(1,285)
Fair Value	$ 0	$ 14,129,723
Number of debt securities held \| security		6
Aggregate fair value of securities in an unrealized loss position		$ 8,191,315
Number of debt securities in a significant unrealized loss position \| security		0
U.S. government agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		$ 8,987,254
Unrealized Gains		38
Unrealized Losses		(1,033)
Fair Value		8,986,259
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		4,440,689
Unrealized Gains		0
Unrealized Losses		0
Fair Value		4,440,689
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		703,027
Unrealized Gains		0
Unrealized Losses		(252)
Fair Value		$ 702,775

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months.

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