Quarterly report pursuant to Section 13 or 15(d)

Notes Payable - Components of Notes Payable (Details)

v3.10.0.1
Notes Payable - Components of Notes Payable (Details) - USD ($)
$ in Thousands
Sep. 30, 2018
Aug. 09, 2018
May 22, 2018
Dec. 31, 2017
Nov. 21, 2017
Debt Instrument [Line Items]          
Less: Unamortized debt issuance costs $ (7,191)     $ (3,412)  
Total 185,199     96,849  
Unamortized discount 115     424  
Notes payable to KMS' former shareholders, net of $0 and $98 of unamortized discount in 2018 and 2017, respectively          
Debt Instrument [Line Items]          
Unamortized discount 0     98  
Notes payable to SSN's former shareholders, net of $0 and $326 of unamortized discount in 2018 and 2017, respectively          
Debt Instrument [Line Items]          
Unamortized discount 0     326  
6.5% Senior notes          
Debt Instrument [Line Items]          
Unamortized discount 69     0  
7% Senior Notes          
Debt Instrument [Line Items]          
Unamortized discount 46        
Notes Payable | Notes payable to clearing firm under forgivable loans          
Debt Instrument [Line Items]          
Long-term debt 0     2,143  
Notes Payable | Note payable under subsidiary's term loan with bank          
Debt Instrument [Line Items]          
Long-term debt 0     6,563  
Notes Payable | Note payable under subsidiary's revolver with bank          
Debt Instrument [Line Items]          
Long-term debt 121     216  
Notes Payable | Notes payable by subsidiary to certain former shareholders of Highland          
Debt Instrument [Line Items]          
Long-term debt 0     6,738  
Notes Payable | Notes payable to KMS' former shareholders, net of $0 and $98 of unamortized discount in 2018 and 2017, respectively          
Debt Instrument [Line Items]          
Long-term debt 0     1,958  
Notes Payable | Notes payable to SSN's former shareholders, net of $0 and $326 of unamortized discount in 2018 and 2017, respectively          
Debt Instrument [Line Items]          
Long-term debt 0     6,074  
Notes Payable | Notes payable to Kestler Financial Group's former shareholders          
Debt Instrument [Line Items]          
Long-term debt 5,433     0  
Senior Notes | 6.5% Senior notes          
Debt Instrument [Line Items]          
Senior Notes $ 82,740     76,569  
Interest rate 6.50%       6.50%
Senior Notes | 7% Senior Notes          
Debt Instrument [Line Items]          
Senior Notes $ 44,096     0  
Interest rate 7.00%   7.00%    
Senior Notes | 7.25% Senior Notes          
Debt Instrument [Line Items]          
Senior Notes $ 60,000     $ 0  
Interest rate 7.25% 7.25%