Loans - Pre-Modification and Post-Modification Outstanding Recorded Investments (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) contract	Dec. 31, 2017 USD ($) contract
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | contract	44	106
Pre-Modification Outstanding Recorded Investment	$ 24,025	$ 102,632
Post-Modification Outstanding Recorded Investment	$ 23,623	$ 95,227
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | contract	25	90
Pre-Modification Outstanding Recorded Investment	$ 16,251	$ 75,894
Post-Modification Outstanding Recorded Investment	$ 15,105	$ 69,020
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | contract	9	9
Pre-Modification Outstanding Recorded Investment	$ 6,175	$ 24,969
Post-Modification Outstanding Recorded Investment	$ 6,956	$ 24,480
Commercial real estate | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | contract	8	6
Pre-Modification Outstanding Recorded Investment	$ 5,643	$ 23,781
Post-Modification Outstanding Recorded Investment	$ 6,600	$ 23,548
Commercial real estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | contract	1	3
Pre-Modification Outstanding Recorded Investment	$ 532	$ 1,188
Post-Modification Outstanding Recorded Investment	$ 356	$ 932
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | contract	8	7
Pre-Modification Outstanding Recorded Investment	$ 1,500	$ 1,769
Post-Modification Outstanding Recorded Investment	$ 1,461	$ 1,727
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | contract	2
Pre-Modification Outstanding Recorded Investment	$ 99
Post-Modification Outstanding Recorded Investment	$ 101