Annual report pursuant to Section 13 and 15(d)

Acquisitions (Narrative) (Details)

v3.8.0.1
Acquisitions (Narrative) (Details)
$ in Thousands
 1 Months Ended 12 Months Ended
Jan. 02, 2015
USD ($)
Dec. 31, 2016
USD ($)
Sep. 30, 2016
USD ($)
Jul. 31, 2015
USD ($)
earn_out_scenario
Jun. 30, 2015
USD ($)
earn_out_scenario
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Business Acquisition [Line Items]                  
Acquisition-related expenses           $ 3,469 $ 1,357 $ 940  
Contingent consideration payable   $ 7,144       2,104 7,144    
Goodwill   124,031       124,210 124,031 125,572  
SSN                  
Business Acquisition [Line Items]                  
Consideration transferred $ 47,287                
Goodwill, deductible period for income tax purposes 15 years                
Cash paid in acquisition           $ 0 0 25,000  
Identifiable intangible assets $ 57                
Goodwill $ 9,282                
SSN | Promissory Notes                  
Business Acquisition [Line Items]                  
Imputed interest rate 5.10%                
SSN | Promissory Notes | 0.41% Promissory Notes                  
Business Acquisition [Line Items]                  
Notes payable-long term $ 25,000                
SSN | Promissory Notes | 1.74% Promissory Notes                  
Business Acquisition [Line Items]                  
Notes payable-long term $ 20,000                
Interest rate, stated percentage 1.74%                
Term 4 years                
Periodic payment $ 18,697                
Imputed interest rate 5.10%                
Amount to be paid in excess of net worth of promissory notes $ 3,590                
Acquisition-related expenses               $ 51 $ 523
Wall Street Financial Group                  
Business Acquisition [Line Items]                  
Consideration transferred     $ 3,468            
Cash paid in acquisition     1,192            
Contingent consideration payable     $ 2,276            
Period following closing     3 years            
Identifiable intangible assets     $ 3,070            
Goodwill     $ 398            
Foothill Securities, Inc                  
Business Acquisition [Line Items]                  
Consideration transferred   5,571              
Cash paid in acquisition   2,905              
Contingent consideration payable   $ 2,666         2,666    
Period following closing   3 years              
Identifiable intangible assets   $ 4,640         4,640    
Goodwill   $ 931         $ 931    
Select Brokerage Services Inc.                  
Business Acquisition [Line Items]                  
Consideration transferred       $ 2,019          
Cash paid in acquisition       503          
Contingent consideration payable       1,012          
Identifiable intangible assets       $ 2,019          
Number of earn-out scenarios | earn_out_scenario       3          
Deferred payment on first anniversary       $ 504          
Earn out period       4 years          
Dalton Strategic Investment Services, Inc.                  
Business Acquisition [Line Items]                  
Consideration transferred         $ 2,689        
Cash paid in acquisition         2,100        
Contingent consideration payable         589        
Identifiable intangible assets         2,675        
Goodwill         $ 14        
Number of earn-out scenarios | earn_out_scenario         3        
Earn out period         3 years