Quarterly report pursuant to Section 13 or 15(d)

Summary of Restricted Share Units Activity (Detail)

v3.8.0.1
Summary of Restricted Share Units Activity (Detail) - Restricted Share Units
3 Months Ended
Mar. 31, 2018
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares  
Number of Restricted Shares, Beginning Balance | shares 242,684
Number of Restricted Shares, Shares Granted | shares 119,167
Number of Restricted Shares, Shares Vested | shares (11,350)
Number of Restricted Shares, Shares Forfeited | shares (3,334)
Number of Restricted Shares, Ending Balance | shares 347,167
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value  
Weighted Average Grant Date Fair Value Per Share, Beginning Balance | $ / shares $ 7.17
Weighted Average Grant Date Fair Value Per Share, Shares Granted | $ / shares 4.25
Weighted Average Grant Date Fair Value Per Share, Shares Vested | $ / shares 5.12
Weighted Average Grant Date Fair Value Per Share, Shares Forfeited | $ / shares 6.35
Weighted Average Grant Date Fair Value Per Share, Ending Balance | $ / shares $ 4.82