Annual report pursuant to Section 13 and 15(d)

Intangible Assets - Summary of Intangible Assets (Detail)

v3.19.3.a.u2
Intangible Assets - Summary of Intangible Assets (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Cost of intangible assets gross $ 46,527 $ 25,027 $ 25,027
Accumulated amortization, beginning balance (15,134) (13,449)  
Amortization expense (2,107) (1,685) (1,826)
Accumulated amortization, ending balance (17,241) (15,134) (13,449)
Net book value $ 29,286 9,893  
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 44,060 22,560 22,560
Accumulated amortization, beginning balance (12,887) (11,367)  
Amortization expense (1,946) (1,520)  
Accumulated amortization, ending balance (14,833) (12,887) (11,367)
Net book value $ 29,227 $ 9,673  
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 2,467 $ 2,467 2,467
Accumulated amortization, beginning balance (2,247) (2,082)  
Amortization expense (161) (165)  
Accumulated amortization, ending balance (2,408) (2,247) $ (2,082)
Net book value $ 59 $ 220  
Other Intangible Assets | Minimum      
Useful lives 3 years 3 years  
Other Intangible Assets | Maximum      
Useful lives 5 years 5 years