Quarterly report pursuant to Section 13 or 15(d)

Property and Equipment - Additional Information (Detail)

v3.10.0.1
Property and Equipment - Additional Information (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Property, Plant and Equipment [Line Items]        
Depreciation expense $ 215 $ 134 $ 371 $ 268
Asset Under Construction [Member]        
Property, Plant and Equipment [Line Items]        
Capitalized cost from assets under construction 10,700   10,700  
Assets Under Construction Held Under Finance Lease [Member]        
Property, Plant and Equipment [Line Items]        
Capitalized cost from assets under construction $ 10,200   $ 10,200