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Face (par) amount of debt instrument at time of issuance.

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Notes Payable and Other Long-Term Liabilities - Additional Information (Detail)		3 Months Ended			6 Months Ended	9 Months Ended
	Jul. 11, 2018	Sep. 30, 2019 USD ($)	Sep. 30, 2019 EUR (€)	Sep. 30, 2018 USD ($)	Jun. 30, 2019	Sep. 30, 2019 USD ($) FundingArrangement	Sep. 30, 2019 EUR (€) FundingArrangement	Sep. 30, 2018 USD ($)	Jan. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jul. 27, 2018 USD ($)	Jul. 26, 2018 USD ($)
Debt Instrument [Line Items]
Line of credit facility, renewed credit agreement expiration period	6 months
Line of credit facility, maximum borrowing capacity \| $											$ 1,750,000	$ 250,000
Line of credit facility, remaining balance \| $									$ 0	$ 0
Line of Credit Facility Expiration					2019-01
Revenue \| $		$ 643,978		$ 2,634,393		$ 5,225,600		$ 7,742,514
Repayments of notes payable \| $						$ 186,940
BPI France Notes [Member]
Debt Instrument [Line Items]
Number of non-interest bearing research and development funding arrangements \| FundingArrangement						2	2
Percentage of fund to be withdrawn upon signing of arrangements						50.00%	50.00%
Additional percentage of fund to be withdrawn, contingent upon financial audit and technical progress report						30.00%	30.00%
Research and development funding arrangements extended period						2 years	2 years
Total long-term debt \| €			€ 500,000				€ 500,000
Paid in excess of allowable funding amount \| €							102,951
Paid the remaining note payable amount \| €							62,500
Repayments of notes payable \| $						$ 186,940
BPI France Notes [Member] \| Research Funding First Arrangement [Member]
Debt Instrument [Line Items]
Debt instrument, face amount \| €			750,000				750,000
BPI France Notes [Member] \| Research Funding Second Arrangement [Member]
Debt Instrument [Line Items]
Debt instrument, face amount \| €			250,000				250,000
BPI France Notes [Member] \| Grant [Member]
Debt Instrument [Line Items]
Long-term debt converted amount						265,540	238,229
Revenue		$ 265,540	€ 238,229			$ 265,540	€ 238,229