Loans and allowance for loan losses - Information on PPP loans (Details)
3 Months Ended
Mar. 31, 2021
USD ($)
Institution
loan
item
Mar. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Loan amount $ 584,874,000   $ 554,985,000
SBA fee earned $ 6,778,000 $ 5,369,000  
PPP Loans      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of businesses and non profits funded by PPP loans | Institution 2,200    
Number of jobs protected by PPP loans | item 28,000    
Number of loans granted | loan 2,210    
Loan amount $ 159,769,000    
Loan forgiveness amount $ 45,872,000    
PPP loan $350,000      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of loans granted | loan 2,128    
Loan amount $ 84,624,000    
PPP loan $350,000 - $2 million      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of loans granted | loan 76    
Loan amount $ 52,043,000    
PPP loan > $2 million      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of loans granted | loan 6    
Loan amount $ 23,102,000    
Round 1 | PPP Loans      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of loans granted | loan 1,526    
Loan amount $ 90,917,000    
Round 1 | PPP loan $350,000      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of loans granted | loan 1,484    
Loan amount $ 41,939,000    
Round 1 | PPP loan $350,000 - $2 million      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of loans granted | loan 36    
Loan amount $ 25,876,000    
Round 1 | PPP loan > $2 million      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of loans granted | loan 6    
Loan amount $ 23,102,000    
Round 2 | PPP Loans      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of loans granted | loan 684    
Loan amount $ 68,852,000    
Round 2 | PPP loan $350,000      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of loans granted | loan 644    
Loan amount $ 42,685,000    
Round 2 | PPP loan $350,000 - $2 million      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of loans granted | loan 40    
Loan amount $ 26,167,000