Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jan. 01, 2020	Dec. 31, 2019	Jan. 01, 2019
Significant Accounting Policies [Line Items]
Contract with customer, liability	$ 4,900			$ 3,900
Revenues	67,099	$ 51,195
Accounts Receivable, Credit Loss Expense (Reversal)	800	300
Retained earnings	$ 60,202			69,093
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.
Operating lease right-of-use asset	$ 23,908			28,346
Operating lease obligations	$ 25,889			30,750
Minimum
Significant Accounting Policies [Line Items]
Amortization period of deferred cash retention awards	3 years
Maximum
Significant Accounting Policies [Line Items]
Amortization period of deferred cash retention awards	5 years
Equipment
Significant Accounting Policies [Line Items]
Estimated useful lives of fixed assets (in years)	5 years
Furniture and Fixtures
Significant Accounting Policies [Line Items]
Estimated useful lives of fixed assets (in years)	7 years
Leasehold Improvements
Significant Accounting Policies [Line Items]
Estimated useful lives of fixed assets (in years)	10 years
Restricted Stock | Minimum
Significant Accounting Policies [Line Items]
Restricted stock units, amortization service period (years)	3 years
Restricted Stock | Maximum
Significant Accounting Policies [Line Items]
Restricted stock units, amortization service period (years)	5 years
Capital advisory engagements
Significant Accounting Policies [Line Items]
Contract with customer, liability, revenue recognized	$ 600	2,400
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)
Accounting Standards Update 2016-13 | Cumulative Effect, Period of Adoption, Adjustment
Significant Accounting Policies [Line Items]
Retained earnings			$ (100)
Primary Capital Advisory Engagements
Significant Accounting Policies [Line Items]
Long term receivables related to private equity and real estate capital advisory engagements	$ 9,000			$ 18,000
Installments period (in years)	3 years
Reimbursement Revenue
Significant Accounting Policies [Line Items]
Revenues	$ 1,300	$ 1,000
Retained earnings
Significant Accounting Policies [Line Items]
Cumulative effect of the change in accounting principle related to credit losses			$ (123)		$ 0