Annual report pursuant to Section 13 and 15(d)

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

v3.3.1.900
Stock-Based Compensation Plans - Stock-Based Compensation Expense (Detail) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2013
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock based compensation in connection with IPO $ 30,900     $ 30,886
Share-based compensation expense - Independent contractors   $ 4,159 $ 3,892 168
Allocated share-based compensation expense   7,114 5,034 35,841
Prior to IPO Restricted stock and SARs [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense       4,679
Employee Stock Purchase Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense   285 128  
Restricted Stock Awards [Member] | Non-Employee Directors [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense   319 197 20
Restricted Stock Units (RSUs) [Member] | Employees [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense   $ 2,351 $ 817 $ 88