Loans - Pre-Modification and Post-Modification Outstanding Recorded Investments (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Contract	Dec. 31, 2015 USD ($) Contract
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | Contract	34	33
Pre-Modification Outstanding Recorded Investment	$ 31,354	$ 19,593
Post-Modification Outstanding Recorded Investment	$ 28,872	$ 18,591
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | Contract	19	17
Pre-Modification Outstanding Recorded Investment	$ 18,186	$ 8,409
Post-Modification Outstanding Recorded Investment	$ 16,277	$ 6,793
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | Contract	7	7
Pre-Modification Outstanding Recorded Investment	$ 11,247	$ 7,414
Post-Modification Outstanding Recorded Investment	$ 10,718	$ 8,100
Commercial real estate | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | Contract	4	5
Pre-Modification Outstanding Recorded Investment	$ 8,325	$ 6,768
Post-Modification Outstanding Recorded Investment	$ 7,092	$ 6,709
Commercial real estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | Contract	3	2
Pre-Modification Outstanding Recorded Investment	$ 2,922	$ 646
Post-Modification Outstanding Recorded Investment	$ 3,626	$ 1,391
Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | Contract	7	7
Pre-Modification Outstanding Recorded Investment	$ 1,867	$ 2,659
Post-Modification Outstanding Recorded Investment	$ 1,826	$ 2,603
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Contracts | Contract	1	2
Pre-Modification Outstanding Recorded Investment	$ 54	$ 1,111
Post-Modification Outstanding Recorded Investment	$ 51	$ 1,095