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Accounts Payable and Accrued Liabilities - Accounts Payable and Accrued Liabilities (Detail) - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Payables and Accruals [Abstract]      
Trade and accrued payables $ 7,409 $ 8,279  
Warranty 227 258 $ 287
Customer deposits 850 575  
Other 0 4  
Accounts Payable and Accrued Liabilities $ 8,486 $ 9,116