Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Detail)

v3.19.1
Income Taxes - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Income Tax [Line Items]      
Income tax expense $ 0 $ 0 $ 0
U.S. Tax Authority      
Income Tax [Line Items]      
Federal statutory tax rate 21.00% 34.00%  
Ireland      
Income Tax [Line Items]      
Net operating loss carryforwards $ 13,648,000 $ 5,409,000 $ 1,706,000