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 9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Sep. 30, 2014
Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Share-based compensation expense - Independent contractors $ 1,136   $ 2,549  
Allocated share-based compensation expense 1,417 2,053 3,275 4,679
Restricted stock and SARs (prior to IPO) [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense   2,053   4,679
Employee Stock Purchase Plan [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense 45   68  
Restricted Stock [Member] | Non-employee directors [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense 61   137  
Restricted Stock Units (RSUs) [Member] | Employees [Member]
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense $ 175   $ 521