Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation Plans - Stock-Based Compensation Expense (Detail)

v3.7.0.1
Stock-Based Compensation Plans - Stock-Based Compensation Expense (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based compensation expense - Independent contractors $ 817 $ 530
Allocated share-based compensation expense 1,866 1,325
Employee Stock Purchase Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Allocated share-based compensation expense 46 48
Restricted Stock Awards [Member] | Non-Employee Directors [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Allocated share-based compensation expense 89 89
Restricted Stock Units [Member] | Employees [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Allocated share-based compensation expense $ 914 $ 658