Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Components of Stock-Based Compensation Included in Consolidated Statements of Net and Comprehensive Income (Detail)

v2.4.0.8
Stock-Based Compensation - Components of Stock-Based Compensation Included in Consolidated Statements of Net and Comprehensive Income (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2014
Jun. 30, 2013
Jun. 30, 2014
Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation expense - Independent contractors $ 926   $ 1,413  
Allocated share-based compensation expense 1,141 2,190 1,858 2,626
Restricted stock and SARs (prior to IPO) [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense   2,190   2,626
Employee Stock Purchase Plan [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense 23   23  
Restricted Stock [Member] | Non-employee directors [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense 46   76  
Restricted Stock Units (RSUs) [Member] | Employees [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense $ 146   $ 346