Annual report pursuant to Section 13 and 15(d)

Selected Balance Sheet Data - Components of Deferred Compensation and Commissions (Detail)

v3.10.0.1
Selected Balance Sheet Data - Components of Deferred Compensation and Commissions (Detail) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Stock appreciation rights ("SARs") liability $ 1,810 $ 1,662
Deferred compensation liability 1,288 1,261
Deferred compensation and commissions, current 47,910 49,180
Stock appreciation rights ("SARs") liability 19,299 20,217
Deferred compensation liability 6,605 7,220
Deferred compensation and commissions, non-current 49,887 49,361
Current [Member]    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Commissions payable to investment sales and financing professionals 44,812 46,257
Non-Current [Member]    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Commissions payable to investment sales and financing professionals $ 23,983 $ 21,924