Loans, Leases and Other Real Estate - Company's Non-Performing Assets and Its Accruing Troubled Debt Restructurings (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-accrual loans and leases	$ 11,124	$ 13,655
Other real estate and other repossessed assets	2,754	843
TOTAL NON-PERFORMING ASSETS	13,878	14,498
Troubled debt restructurings, still accruing	9,030	11,462
Commercial, secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-accrual loans and leases	5,737	5,890
Commercial, industrial and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-accrual loans and leases	1,189	184
Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-accrual loans and leases	441	144
Real estate - residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-accrual loans and leases	2,347	3,860
Real estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-accrual loans and leases	0	1,472
Home equity and consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-accrual loans and leases	$ 1,410	$ 2,105