Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Significant Of Accounting Policies [Line Items]
Restricted cash	$ 492	$ 24
Impairment loss of property and equipment	235
Foreign exchange losses	$ 51	19
Series B Preferred Stock [Member]
Significant Of Accounting Policies [Line Items]
Deferred issuance costs		$ 85
Expected Dividend Yield [Member]
Significant Of Accounting Policies [Line Items]
Expected cash dividend yield	0