Quarterly report pursuant to Section 13 or 15(d)

Revenue from Contracts with Customers - Disaggregation of Revenue (Details)

v3.8.0.1
Revenue from Contracts with Customers - Disaggregation of Revenue (Details)
$ in Thousands
 3 Months Ended
Mar. 31, 2018
USD ($)
Disaggregation of Revenue [Line Items]  
Total revenues $ 329,384
Corporate  
Disaggregation of Revenue [Line Items]  
Total revenues 481
Commissions  
Disaggregation of Revenue [Line Items]  
Total revenues 163,286
Commissions | Corporate  
Disaggregation of Revenue [Line Items]  
Total revenues 0
Advisory fees  
Disaggregation of Revenue [Line Items]  
Total revenues 114,383
Advisory fees | Corporate  
Disaggregation of Revenue [Line Items]  
Total revenues 54
Investment banking  
Disaggregation of Revenue [Line Items]  
Total revenues 16,490
Investment banking | Corporate  
Disaggregation of Revenue [Line Items]  
Total revenues 0
Principal transactions  
Disaggregation of Revenue [Line Items]  
Total revenues 167
Principal transactions | Corporate  
Disaggregation of Revenue [Line Items]  
Total revenues 0
Interest and dividends  
Disaggregation of Revenue [Line Items]  
Total revenues 787
Interest and dividends | Corporate  
Disaggregation of Revenue [Line Items]  
Total revenues 178
Service fees  
Disaggregation of Revenue [Line Items]  
Total revenues 24,902
Service fees | Corporate  
Disaggregation of Revenue [Line Items]  
Total revenues 194
Other income  
Disaggregation of Revenue [Line Items]  
Total revenues 9,369
Other income | Corporate  
Disaggregation of Revenue [Line Items]  
Total revenues 55
Independent Advisory and Brokerage Services  
Disaggregation of Revenue [Line Items]  
Total revenues 275,529
Independent Advisory and Brokerage Services | Commissions  
Disaggregation of Revenue [Line Items]  
Total revenues 129,745
Independent Advisory and Brokerage Services | Advisory fees  
Disaggregation of Revenue [Line Items]  
Total revenues 112,513
Independent Advisory and Brokerage Services | Investment banking  
Disaggregation of Revenue [Line Items]  
Total revenues 116
Independent Advisory and Brokerage Services | Principal transactions  
Disaggregation of Revenue [Line Items]  
Total revenues 11
Independent Advisory and Brokerage Services | Interest and dividends  
Disaggregation of Revenue [Line Items]  
Total revenues 534
Independent Advisory and Brokerage Services | Service fees  
Disaggregation of Revenue [Line Items]  
Total revenues 24,140
Independent Advisory and Brokerage Services | Other income  
Disaggregation of Revenue [Line Items]  
Total revenues 8,470
Ladenburg  
Disaggregation of Revenue [Line Items]  
Total revenues 22,314
Ladenburg | Commissions  
Disaggregation of Revenue [Line Items]  
Total revenues 3,213
Ladenburg | Advisory fees  
Disaggregation of Revenue [Line Items]  
Total revenues 1,816
Ladenburg | Investment banking  
Disaggregation of Revenue [Line Items]  
Total revenues 16,374
Ladenburg | Principal transactions  
Disaggregation of Revenue [Line Items]  
Total revenues 156
Ladenburg | Interest and dividends  
Disaggregation of Revenue [Line Items]  
Total revenues 75
Ladenburg | Service fees  
Disaggregation of Revenue [Line Items]  
Total revenues 568
Ladenburg | Other income  
Disaggregation of Revenue [Line Items]  
Total revenues 112
Insurance Brokerage  
Disaggregation of Revenue [Line Items]  
Total revenues 31,060
Insurance Brokerage | Commissions  
Disaggregation of Revenue [Line Items]  
Total revenues 30,328
Insurance Brokerage | Advisory fees  
Disaggregation of Revenue [Line Items]  
Total revenues 0
Insurance Brokerage | Investment banking  
Disaggregation of Revenue [Line Items]  
Total revenues 0
Insurance Brokerage | Principal transactions  
Disaggregation of Revenue [Line Items]  
Total revenues 0
Insurance Brokerage | Interest and dividends  
Disaggregation of Revenue [Line Items]  
Total revenues 0
Insurance Brokerage | Service fees  
Disaggregation of Revenue [Line Items]  
Total revenues 0
Insurance Brokerage | Other income  
Disaggregation of Revenue [Line Items]  
Total revenues $ 732