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Stock-Based Compensation - Restricted Stock Units - Service-Based - Additional Information (Detail) - Service Based Restricted Stock Units [Member] - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted shares vested intrinsic value $ 30 $ 29
Unrecognized compensation expense $ 100  
Weighted average period 1 year 2 months 12 days