Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Additional Information 1 (Detail)

v3.8.0.1
Common Stock - Additional Information 1 (Detail) - USD ($)
3 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized compensation expense related to stock options granted $ 1,800,000   $ 2,000,000
Common shares reserved for awards currently outstanding     0
Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted-average period, restricted stock awards 3 years 2 months 12 days    
Restricted Stock Unit [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted-average period, restricted stock awards 3 years 1 month 6 days    
Award vesting period 4 years    
Stock based compensation expense $ 37,000    
Common shares reserved for awards currently outstanding 205,104 210,160  
Total unrecognized compensation expense related to the Company's restricted stock unit awards $ 500,000