Quarterly report pursuant to Section 13 or 15(d)

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

v2.4.0.8
Stock-Based Compensation Plans - Components of Stock-Based Compensation Included in Consolidated Statements of Net and Comprehensive Income (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based compensation expense - Independent contractors $ 487  
Allocated share-based compensation expense 717 436
Restricted stock and SARs (prior to IPO) [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Allocated share-based compensation expense   436
Restricted Stock [Member] | Non-employee directors [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Allocated share-based compensation expense 30  
Restricted Stock Units (RSUs) [Member] | Employees [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Allocated share-based compensation expense $ 200