Quarterly report pursuant to Section 13 or 15(d)

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

v3.8.0.1
Selected Balance Sheet Data - Components of Deferred Compensation and Commissions (Detail) - USD ($)
$ in Thousands
Sep. 30, 2017
Dec. 31, 2016
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Stock appreciation rights ("SARs") liability $ 1,734 $ 1,366
Deferred compensation liability 1,396 607
Total 29,477 44,754
Stock appreciation rights ("SARs") liability 19,913 20,949
Deferred compensation liability 7,261 6,405
Total 43,591 44,455
Current [Member]    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Commissions payable to investment sales and financing professionals 26,347 42,781
Non-Current [Member]    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Commissions payable to investment sales and financing professionals $ 16,417 $ 17,101