Revenue - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contracts with Customers [Line Items]
Contract with Customer, Liability, Revenue Recognized	$ 15,115	$ 16,468
Period in Which Performance Obligations Under Client Arrangements Settled	1 year
Underwriting Fees [Member]
Revenue from Contracts with Customers [Line Items]
Reimbursement Revenue		4,680
Professional Fees [Member]
Revenue from Contracts with Customers [Line Items]
Reimbursable Expense		2,340
Travel and Related Expenses [Member]
Revenue from Contracts with Customers [Line Items]
Reimbursable Expense		460
Communications and Information Services [Member]
Revenue from Contracts with Customers [Line Items]
Reimbursable Expense		476
Other Operating Expenses [Member]
Revenue from Contracts with Customers [Line Items]
Reimbursable Expense		1,404
Investment Banking [Member] | Advisory Fees [Member]
Revenue from Contracts with Customers [Line Items]
Revenue, Variable Consideration Recognized		$ 3,374