Summary of Significant Accounting Policies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2020 USD ($)	Jan. 01, 2019 USD ($)	Jan. 01, 2018 USD ($)
Significant Accounting Policies [Line Items]
Contract with customer, liability	$ 3,900	$ 5,600				$ 12,300
Allowance for doubtful accounts	1,197	0	$ 0
Long term receivables related to primary capital advisory engagements	$ 10,500	20,000
Installments period	3 years
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
Operating lease right-of-use asset	$ 28,346
Operating lease obligations	30,750
Total assets	494,375	485,700	610,817
Retained earnings	$ 69,093	63,427
Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Operating lease right-of-use asset					$ 38,100
Operating lease obligations					38,100
Deferred rent					$ (3,200)
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
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]
Revenue from contract with customer, excluding assessed tax	$ 6,400	7,000	4,700
Advisory Fees [Member]
Significant Accounting Policies [Line Items]
Allowance for doubtful accounts	1,200	300	$ 1,100
Advisory Services
Significant Accounting Policies [Line Items]
Contract with customer, liability, revenue recognized	$ 4,700	$ 9,300
Forecast | Accounting Standards Update 2016-13
Significant Accounting Policies [Line Items]
Total assets				$ (200)
Retained earnings				$ (200)