Annual report pursuant to Section 13 and 15(d)

Intangible Assets - Summary of Intangible Assets (Detail)

v3.20.4
Intangible Assets - Summary of Intangible Assets (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Cost of intangible assets gross, beginning balance $ 46,527 $ 25,027  
Disposal (6)    
Cost of intangible assets gross, ending balance 46,521 46,527 $ 25,027
Accumulated amortization, beginning balance (17,241) (15,134)  
Amortization expense (2,733) (2,107) (1,685)
Disposal 6    
Accumulated amortization, ending balance (19,968) (17,241) (15,134)
Net book value $ 26,553 29,286  
Minimum      
Useful lives 3 years    
Maximum      
Useful lives 20 years    
Cortina Asset Management, LLC      
Acquisition of Cortina   21,500  
Customer Relationships      
Cost of intangible assets gross, beginning balance $ 44,060 22,560  
Cost of intangible assets gross, ending balance 44,060 44,060 22,560
Accumulated amortization, beginning balance (14,833) (12,887)  
Amortization expense (2,674) (1,946)  
Accumulated amortization, ending balance (17,507) (14,833) (12,887)
Net book value $ 26,553 $ 29,227  
Customer Relationships | Minimum      
Useful lives 10 years 10 years  
Customer Relationships | Maximum      
Useful lives 20 years 20 years  
Customer Relationships | Cortina Asset Management, LLC      
Acquisition of Cortina   $ 21,500  
Other Intangible Assets      
Cost of intangible assets gross, beginning balance $ 2,467 2,467  
Disposal (6)    
Cost of intangible assets gross, ending balance 2,461 2,467 2,467
Accumulated amortization, beginning balance (2,408) (2,247)  
Amortization expense (59) (161)  
Disposal 6    
Accumulated amortization, ending balance $ (2,461) (2,408) $ (2,247)
Net book value   $ 59  
Other Intangible Assets | Minimum      
Useful lives 3 years 3 years  
Other Intangible Assets | Maximum      
Useful lives 5 years 5 years