Loans and the Allowance for Credit Losses - Recorded Investment in Non-Accrual Loans and TDRs (Detail) - USD ($)
$ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
| Financing Receivable, Impaired [Line Items] |
|
|
| Non-accrual loans |
$ 32,386
|
$ 36,825
|
| TDRs |
9,255
|
9,436
|
| Accruing TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
6,858
|
6,571
|
| Non-Accrual TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
2,397
|
2,865
|
| Commercial Real Estate - Land and Construction [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| Non-accrual loans |
800
|
239
|
| TDRs |
2
|
3
|
| Commercial Real Estate - Land and Construction [Member] | Non-Accrual TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
2
|
3
|
| Commercial Real Estate - Improved Property [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| Non-accrual loans |
10,821
|
13,318
|
| TDRs |
2,092
|
2,078
|
| Commercial Real Estate - Improved Property [Member] | Accruing TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
1,602
|
1,650
|
| Commercial Real Estate - Improved Property [Member] | Non-Accrual TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
490
|
428
|
| Commercial and Industrial [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| Non-accrual loans |
2,373
|
2,958
|
| TDRs |
217
|
225
|
| Commercial and Industrial [Member] | Accruing TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
123
|
128
|
| Commercial and Industrial [Member] | Non-Accrual TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
94
|
97
|
| Home Equity [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| Non-accrual loans |
4,540
|
4,762
|
| TDRs |
651
|
744
|
| Home Equity [Member] | Accruing TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
431
|
407
|
| Home Equity [Member] | Non-Accrual TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
220
|
337
|
| Commercial Real Estate [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| Non-accrual loans |
11,621
|
13,557
|
| TDRs |
2,094
|
2,081
|
| Commercial Real Estate [Member] | Accruing TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
1,602
|
1,650
|
| Commercial Real Estate [Member] | Non-Accrual TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
492
|
431
|
| Residential Real Estate [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| Non-accrual loans |
13,149
|
14,661
|
| TDRs |
6,127
|
6,201
|
| Residential Real Estate [Member] | Accruing TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
4,602
|
4,321
|
| Residential Real Estate [Member] | Non-Accrual TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
1,525
|
1,880
|
| Consumer [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| Non-accrual loans |
703
|
887
|
| TDRs |
166
|
185
|
| Consumer [Member] | Accruing TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
100
|
65
|
| Consumer [Member] | Non-Accrual TDRs [Member] |
|
|
| Financing Receivable, Impaired [Line Items] |
|
|
| TDRs |
$ 66
|
$ 120
|