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Notes Payable and Other Liabilities - Additional Information (Detail)		12 Months Ended
	Jul. 11, 2018	Dec. 31, 2018 USD ($) FundingArrangement d $ / shares shares	Dec. 31, 2017 USD ($)	Dec. 31, 2018 EUR (€) shares	Dec. 29, 2018	Jul. 27, 2018 USD ($)	Jun. 29, 2018 USD ($) shares	Dec. 31, 2017 EUR (€)	Mar. 09, 2017 shares
Debt Instrument [Line Items]
Line of credit facility, renewed credit agreement expiration period	6 months
Line of credit facility, maximum borrowing capacity		$ 250,000				$ 1,750,000
Line of credit facility, remaining balance		$ 0
Line of credit facility, annual interest rate		8.00%
Line of Credit Facility Expiration		2019-01
Total long-term debt		$ 572,770	$ 599,927	€ 500,000				€ 500,000
Note classified as short term		71,596	49,702
Amortization of lease incentive obligations		115,782	29,854
Shares of common stock called by warrants \| shares									1,659
Convertible Debt [Member]
Debt Instrument [Line Items]
Interest expense		293,009
Convertible note unamortized discount		180,611
Debt issuance costs		58,172
Additional interest earned		54,226
First Exchange Warrants [Member]
Debt Instrument [Line Items]
Convertible notes principal balance		$ 1,500,000					$ 1,500,000
Shares of common stock called by warrants \| shares		73,530		73,530			53,125
Convertible debt, interest rate in event of default		112.00%
Conversion price per share \| $ / shares		$ 20.40
Weighted average prices of common stock		75.00%
Weighted average price per share of common stock \| $ / shares		$ 4.50
Number of trading days \| d		20
Interest payable					1.00%
BPI France Notes [Member]
Debt Instrument [Line Items]
Number of non-interest bearing research and development funding arrangements \| FundingArrangement		2
Percentage of fund to be withdrawn upon signing of arrangements		50.00%
Additional percentage of fund to be withdrawn, contingent upon financial audit and technical progress report		30.00%
Research and development funding arrangements extended period		2 years
Total long-term debt		$ 501,174	$ 599,927
Note classified as short term		71,596
Note classified as long term		$ 501,174
BPI France Notes [Member] \| Research Funding First Arrangement [Member]
Debt Instrument [Line Items]
Debt instrument, face amount \| €				€ 750,000
Method of repayment		sixteen quarterly installments from June 2019 through March 2023
BPI France Notes [Member] \| Research Funding Second Arrangement [Member]
Debt Instrument [Line Items]
Debt instrument, face amount \| €				€ 250,000
Method of repayment		sixteen quarterly installments from June 2019 through March 2023
Line of Credit [Member]
Debt Instrument [Line Items]
Interest expense		$ 2,889