Quarterly report pursuant to Section 13 or 15(d)

Net Capital Requirements (Details)

v3.10.0.1
Net Capital Requirements (Details) - USD ($)
Sep. 30, 2018
Jan. 01, 2018
Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Stockholder's equity $ 386,307,000 $ 394,488,000 $ 370,379,000
Minimum      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Alternative minimum net capital requirement 262,000    
Securities America      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Regulatory net capital 9,682,000    
Securities America | Minimum      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Alternative minimum net capital requirement 250,000    
Triad      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Regulatory net capital 9,705,000    
Triad | Minimum      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Alternative minimum net capital requirement 250,000    
Investacorp Inc.      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Regulatory net capital 8,533,000    
Investacorp Inc. | Minimum      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Alternative minimum net capital requirement 250,000    
KMS Financial Services, Inc. (KMS)      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Regulatory net capital 7,532,000    
KMS Financial Services, Inc. (KMS) | Minimum      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Alternative minimum net capital requirement 250,000    
Securities Service Network, Inc. (SSN)      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Regulatory net capital 7,829,000    
Ladenburg      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Regulatory net capital 25,774,000    
Premier      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Stockholder's equity 2,732,000    
Premier | Minimum      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Stockholder's equity 1,000,000    
Premier | Minimum | Cash      
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]      
Stockholder's equity $ 250,000