Loans and Allowance for Credit Losses - Troubled Debt Restructured Loans and Commitments (Detail) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
---|---|---|---|
Loans and Leases Receivable Disclosure [Abstract] | |||
Accrual status | $ 11,563 | $ 13,790 | $ 14,139 |
Nonaccrual status | 11,222 | 11,569 | 12,360 |
Total | 22,785 | 25,359 | 26,499 |
Letters of Credit Outstanding, Amount | 60 | 0 | 0 |
Unused lines of credit | $ 54 | $ 358 | $ 3,252 |