Quarterly report pursuant to Section 13 or 15(d)

Acquisitions - Additional Information (Detail)

v3.20.2
Acquisitions - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended 12 Months Ended
Jul. 01, 2019
Apr. 12, 2019
Dec. 13, 2018
Dec. 15, 2015
Mar. 30, 2015
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
Business Acquisition [Line Items]                    
Revenue           $ 27,182,000 $ 27,845,000 $ 79,568,000 $ 74,314,000  
Income before provision for income taxes           4,839,000 6,324,000 18,510,000 14,901,000  
Contingent purchase price payment               741,000 425,000  
Cortina Asset Management, LLC                    
Business Acquisition [Line Items]                    
Aggregate purchase amount               57,824,000    
Equity consideration for SLP acquired           13,500,000   13,500,000   $ 14,000,000
Fair value adjustments to contingent purchase price consideration           1,700,000   (500,000)    
Revenue           3,020,000 3,182,000 8,426,000 3,182,000  
Income before provision for income taxes           1,355,000 976,000 3,428,000 976,000  
Cash paid on date of acquisition                 35,169,000  
Cash paid on date of acquisition               17,072,000    
Cortina Asset Management, LLC | General, Administrative and Other                    
Business Acquisition [Line Items]                    
Costs related to acquisition           5,000 1,147,000 90,000 1,147,000  
Cortina Asset Management, LLC | Purchase Agreement                    
Business Acquisition [Line Items]                    
Aggregate purchase amount $ 33,577,000                  
Percentage to acquire business in cash   80.00%                
Additional percentage to acquire business in cash 80.00% 80.00%                
Business combination consideration partially offset by net closing credits $ 35,072,000                  
Equity consideration for SLP acquired 13,800,000                  
Business combination acquired revenue   $ 13,027,000                
Cortina Asset Management, LLC | Purchase Agreement | Revenue Greater than or Equal to 95% for July 1, 2020 to June 30, 2021                    
Business Acquisition [Line Items]                    
Business combination contingent consideration first retention payment   3,370,000                
Cortina Asset Management, LLC | Purchase Agreement | Revenue Equal to 75% or Less for July 1, 2020 to June 30, 2021                    
Business Acquisition [Line Items]                    
Business combination contingent consideration first retention payment   0                
Cortina Asset Management, LLC | Purchase Agreement | Revenue Between 75% and 95% for July 1, 2020 to June 30, 2021                    
Business Acquisition [Line Items]                    
Business combination contingent consideration first retention payment, minimum   0                
Business combination contingent consideration first retention payment, maximum   3,370,000                
Cortina Asset Management, LLC | Purchase Agreement | Revenue Between 85% and 105% for July 1, 2021 to June 30, 2022                    
Business Acquisition [Line Items]                    
Business combination contingent consideration second retention payment, minimum   0                
Business combination contingent consideration second retention payment, maximum   5,617,000                
Cortina Asset Management, LLC | Purchase Agreement | Revenue Equal to 85% or Less for July 1, 2021 to June 30, 2022                    
Business Acquisition [Line Items]                    
Business combination contingent consideration second retention payment   0                
Cortina Asset Management, LLC | Purchase Agreement | Revenue Between 95% and 140% for July 1, 2022 to June 30, 2023                    
Business Acquisition [Line Items]                    
Business combination contingent consideration growth payment, minimum   0                
Business combination contingent consideration growth payment, maximum   17,222,000                
Cortina Asset Management, LLC | Purchase Agreement | Revenue Equal to 95% or Less for July 1, 2022 to June 30, 2023                    
Business Acquisition [Line Items]                    
Business combination contingent consideration growth payment   0                
Cortina Asset Management, LLC | Purchase Agreement | Maximum                    
Business Acquisition [Line Items]                    
Aggregate purchase amount   44,937,000                
Additional aggregate purchase amount 26,209,000 26,209,000                
Cortina Asset Management, LLC | Purchase Agreement | Maximum | Revenue Between 85% and 105% for July 1, 2021 to June 30, 2022                    
Business Acquisition [Line Items]                    
Business combination contingent consideration second retention payment   5,617,000                
Cortina Asset Management, LLC | Purchase Agreement | Maximum | Revenue Between 95% and 140% for July 1, 2022 to June 30, 2023                    
Business Acquisition [Line Items]                    
Business combination contingent consideration growth payment   $ 17,222,000                
Cortina Asset Management, LLC | Purchase Agreement | SLP                    
Business Acquisition [Line Items]                    
Percentage of business combination consideration issuance   20.00%                
Additional aggregate purchase amount $ 8,952,000                  
Additional percentage of earn out payment paid in cash 20.00% 20.00%                
Potential earn-out payments period 4 years 4 years                
Issuance of Class B shares, Shares 662,713                  
Neosho                    
Business Acquisition [Line Items]                    
Equity consideration for SLP acquired     $ 20,000     1,103,000   1,103,000   1,403,000
Cash paid on date of acquisition     399,000           399,000  
Contingent consideration     1,686,000              
Expected payments on first anniversary of closing date     300,000              
Earn out payments due in two years     100,000              
Earn out payments due in three years     100,000              
Earn out payments due in four years     100,000              
Earn out payments due in five years     $ 100,000              
Percentage of product to obtain earn out payment     50.00%              
Percentage of earn out payment paid in cash     75.00%              
Percentage of earn out payment paid in equity     25.00%              
Contingent purchase price payment           300,000   300,000    
Cappiccille                    
Business Acquisition [Line Items]                    
Equity consideration for SLP acquired           70,000   70,000   101,000
Fair value adjustments to contingent purchase price consideration           0   83,000    
Contingent consideration       $ 354,000            
Contingent purchase price payment           113,000 $ 105,000 113,000 105,000  
Cash paid on date of acquisition       $ 148,000            
Earn out payments percentage on revenue remainder of fiscal year       19.00%            
Earn out payments percentage on revenue due in two years       19.00%            
Earn out payments percentage on revenue due in three years       19.00%            
Earn out payments percentage on revenue due in four years       19.00%            
Earn out payments percentage on revenue due thereafter       19.00%            
Jamison                    
Business Acquisition [Line Items]                    
Equity consideration for SLP acquired         $ 3,562,000          
Fair value adjustments to contingent purchase price consideration           $ 0   70,000    
Contingent consideration         1,429,000     160,000   $ 418,000
Contingent purchase price payment               $ 328,000 $ 320,000  
Cash paid on date of acquisition         $ 3,550,000          
Earn out payments percentage on EBITDA remainder of fiscal year         20.00%          
Earn out payments percentage on EBITDA due in two years         20.00%          
Earn out payments percentage on EBITDA due in three years         20.00%          
Earn out payments percentage on EBITDA due in four years         20.00%          
Earn out payments percentage on EBITDA due in five years         20.00%          
Earn Out Payments Percentage On EBITDA Due thereafter         20.00%          
Jamison | Seller Note                    
Business Acquisition [Line Items]                    
Promissory note issued         $ 394,000          
Interest on principal amount         5.00%          
Jamison | Principals Notes                    
Business Acquisition [Line Items]                    
Promissory note issued         $ 1,771,000          
Interest on principal amount         5.00%