XML 107 R92.htm IDEA: XBRL DOCUMENT v3.10.0.1
Commitments and Letters of Credit - Notional Amount of Commitments and Letter of Credit Instruments (Detail) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Loss Contingencies [Line Items]      
Commitments Net $ 1,087 $ 114 $ 358
Commitments to extend credit      
Loss Contingencies [Line Items]      
Financial instrument of credit risk 1,883,914 1,840,180  
Financial standby letters of credit      
Loss Contingencies [Line Items]      
Financial instrument of credit risk 18,298 17,946  
Performance standby letters of credit      
Loss Contingencies [Line Items]      
Financial instrument of credit risk 22,027 20,472  
Commercial letters of credit      
Loss Contingencies [Line Items]      
Financial instrument of credit risk $ 887 $ 1,149