Summary of Significant Accounting Policies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Segment	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 01, 2019 USD ($)	Jan. 01, 2018 USD ($)
Significant Accounting Policies [Line Items]
Advisory revenues	$ 349,800	$ 237,997	$ 334,787
Contract with customer, liability	5,600				$ 12,300
Bad debt expense	300	1,100	400
Long term receivables related to primary capital advisory engagements	$ 20,000	29,300
Installments period	3 years
Interest income related to capital advisory engagements	$ 800	700	800
Depreciation and amortization of property and equipment	Depreciation is computed using the straight-line method over the life of the assets. Amortization of leasehold improvements is computed using the straight-line method over the lesser of the life of the asset or the remaining term of the lease.
Number of business segments (segment) | Segment	1
Retained earnings	$ 63,427	37,595
Revenue
Significant Accounting Policies [Line Items]
Percentage of revenues earned from interest income and investment gains (losses) on investments (less than)	1.00%
Equipment
Significant Accounting Policies [Line Items]
Estimated useful lives of fixed assets (or lesser for Leaseholds)	5 years
Furniture and fixtures
Significant Accounting Policies [Line Items]
Estimated useful lives of fixed assets (or lesser for Leaseholds)	7 years
Leasehold improvements
Significant Accounting Policies [Line Items]
Estimated useful lives of fixed assets (or lesser for Leaseholds)	10 years
Estimated useful lives of fixed assets, description	Lesser of 10 years or the remaining lease term
Minimum
Significant Accounting Policies [Line Items]
Amortization period of deferred cash retention awards	3 years
Minimum | Restricted Stock
Significant Accounting Policies [Line Items]
Amortization period of restricted stock units	3 years
Maximum
Significant Accounting Policies [Line Items]
Amortization period of deferred cash retention awards	5 years
Maximum | Restricted Stock
Significant Accounting Policies [Line Items]
Amortization period of restricted stock units	5 years
Reimbursement Revenue [Member]
Significant Accounting Policies [Line Items]
Advisory revenues	$ 7,000	4,700	$ 6,500
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09
Significant Accounting Policies [Line Items]
Contract with customer, liability					$ (10,200)
Retained earnings		$ (7,600)
Advisory Services
Significant Accounting Policies [Line Items]
Contract with customer, liability, revenue recognized	$ 9,300
Forecast | Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Lease assets				$ 38,000
Lease liabilities				$ 38,000