Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

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Summary of Significant Accounting Policies - Additional Information (Detail)
 1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2021
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Sep. 30, 2021
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Sep. 30, 2020
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Sep. 30, 2021
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Sep. 30, 2020
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Dec. 31, 2020
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Jul. 29, 2021
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Jun. 26, 2013
Summary Of Significant Accounting Policies [Line Items]                
Number of operating segment | Segment       1        
Cash equivalents, maximum maturity period       90 days        
Equity method investments, unrealized intercompany profit (loss) not eliminated amount       $ 0        
Number of reporting unit | Unit       1   1    
Impairment charges on goodwill   $ 0 $ 0 $ 0 $ 0      
Treasury stock, aggregate price   $ 418,000            
ASU 2016-13                
Summary Of Significant Accounting Policies [Line Items]                
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020 Jan. 01, 2020   Jan. 01, 2020        
Change in accounting principle, accounting standards update, Adopted true true   true        
Change in accounting principle, accounting standards update, Immaterial Effect true true   true        
ASU 2018-15                
Summary Of Significant Accounting Policies [Line Items]                
Change in accounting principle, accounting standards update, adoption date Jan. 01, 2020 Jan. 01, 2020   Jan. 01, 2020        
Change in accounting principle, accounting standards update, Adopted true true   true        
Change in accounting principle, accounting standards update, Immaterial Effect true true   true        
Equity or Balanced Portfolios                
Summary Of Significant Accounting Policies [Line Items]                
Percentage of asset management fee on threshold limit       1.00%        
Asset under management, threshold limit $ 10,000,000 $ 10,000,000   $ 10,000,000        
Percentage of asset management fee on balance       0.60%        
Fixed Income Portfolios                
Summary Of Significant Accounting Policies [Line Items]                
Percentage of asset management fee on threshold limit       0.40%        
Asset under management, threshold limit 10,000,000 10,000,000   $ 10,000,000        
Percentage of asset management fee on balance       0.30%        
Cortina Equity Portfolios                
Summary Of Significant Accounting Policies [Line Items]                
Percentage of asset management fee on balance       0.80%        
Percentage of asset management fee on first threshold limit       1.00%        
Asset under management, first threshold limit 25,000,000 25,000,000   $ 25,000,000        
Percentage of asset management fee on second threshold limit       0.90%        
Asset under management, second threshold limit 25,000,000 25,000,000   $ 25,000,000        
Municipal Value Strategy                
Summary Of Significant Accounting Policies [Line Items]                
Percentage of income from asset management fee       0.65%        
Outsourced Chief Investment Officer Portfolios                
Summary Of Significant Accounting Policies [Line Items]                
Percentage of asset management fee on balance       0.24%        
Percentage of asset management fee on first threshold limit       0.40%        
Asset under management, first threshold limit 50,000,000 50,000,000   $ 50,000,000        
Percentage of asset management fee on second threshold limit       0.32%        
Asset under management, second threshold limit $ 50,000,000 50,000,000   $ 50,000,000        
Minimum                
Summary Of Significant Accounting Policies [Line Items]                
Identifiable finite-lived intangible assets, useful life       3 years        
Minimum | Private Funds                
Summary Of Significant Accounting Policies [Line Items]                
Prior written notice period to terminate investment management agreements       30 days        
Prior written notice period after receiving the affirmative vote, to terminate investment management agreements       60 days        
Percentage of income from asset management fee       0.25%        
Minimum | Non-discretionary Assets                
Summary Of Significant Accounting Policies [Line Items]                
Percentage of income from asset management fee       0.05%        
Maximum                
Summary Of Significant Accounting Policies [Line Items]                
Identifiable finite-lived intangible assets, useful life       20 years        
Maximum | Private Funds                
Summary Of Significant Accounting Policies [Line Items]                
Prior written notice period to terminate investment management agreements       90 days        
Prior written notice period after receiving the affirmative vote, to terminate investment management agreements       90 days        
Percentage of income from asset management fee       1.50%        
Maximum | Non-discretionary Assets                
Summary Of Significant Accounting Policies [Line Items]                
Percentage of income from asset management fee       0.01%        
Leasehold Improvements                
Summary Of Significant Accounting Policies [Line Items]                
Property, plant and equipment, useful life       10 years        
Other Fixed Assets | Minimum                
Summary Of Significant Accounting Policies [Line Items]                
Property, plant and equipment, useful life       3 years        
Other Fixed Assets | Maximum                
Summary Of Significant Accounting Policies [Line Items]                
Property, plant and equipment, useful life       7 years        
Equity Method Investments                
Summary Of Significant Accounting Policies [Line Items]                
Impairment charges related to equity method investments   $ 0 $ 0 $ 0 $ 0      
Class A Common Stock                
Summary Of Significant Accounting Policies [Line Items]                
Treasury stock, purchased | shares 27,197 27,000   27,197        
Treasury stock, aggregate price       $ 418,000        
Common stock, voting rights       one vote for each share        
Class A Common Stock | Maximum                
Summary Of Significant Accounting Policies [Line Items]                
Stock repurchase program, authorized amount             $ 15,000,000  
Class B Common Stock                
Summary Of Significant Accounting Policies [Line Items]                
Common stock, voting rights       one vote for each share        
Class of share exchangeable to another class       one-for-one basis        
Silvercrest L.P | Class A Common Stock                
Summary Of Significant Accounting Policies [Line Items]                
Ownership percentage in a subsidiary 66.80% 66.80%   66.80%       66.80%
Common stock, voting rights       one vote for each share