Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation - Summary of Activity (Detail)

v3.8.0.1
Share-Based Compensation - Summary of Activity (Detail) - 2009 Long-Term Incentive Plan [Member]
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Outstanding at January 1, 2017 1,351,194
Option grants 76,950
Exercised options (15,000)
Cancelled or forfeited options (17,700)
Outstanding at December 31, 2017 1,436,348
Exercisable options at December 31, 2017 209,150
Weighted Average Exercise Price  
Outstanding at January 1, 2017 | $ / shares $ 7.13
Option grants | $ / shares 5.82
Exercised options | $ / shares 5.61
Cancelled or forfeited options | $ / shares 3.21
Outstanding at December 31, 2017 | $ / shares 7.67
Exercisable options at December 31, 2017 | $ / shares $ 6.70
Weighted Average Remaining Contractual Life (in years)  
Outstanding at December 31, 2017 5 years 2 months 12 days
Exercisable options at December 31, 2017 6 years 10 months 24 days
Aggregate Intrinsic Value  
Outstanding at December 31, 2017 | $ $ 13,459
Exercisable options at December 31, 2017 | $ $ 1,192
Restricted Stock Units (RSUs) [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Restricted stock unit grants 70,705
Cancelled or forfeited restricted stock units (29,801)