Loans and the Allowance for Credit Losses - Allowance for Credit Losses and Recorded Investments in Loans (Detail) - USD ($)
$ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
| Financing Receivable, Allowance for Credit Losses [Line Items] |
|
|
|
|
| Allowance for loans individually evaluated for impairment |
$ 387
|
$ 388
|
|
|
| Allowance for loans collectively evaluated for impairment |
45,947
|
44,896
|
|
|
| Allowance for loan commitments |
629
|
574
|
$ 548
|
$ 571
|
| Total allowance for credit losses |
46,963
|
45,858
|
44,609
|
44,245
|
| Individually evaluated for impairment |
2,104
|
3,344
|
|
|
| Collectively evaluated for impairment |
6,312,730
|
6,330,023
|
|
|
| Acquired with deteriorated credit quality |
7,704
|
8,074
|
|
|
| Total loans |
6,322,538
|
6,341,441
|
|
|
| Commercial Real Estate - Land and Construction [Member] |
|
|
|
|
| Financing Receivable, Allowance for Credit Losses [Line Items] |
|
|
|
|
| Allowance for loans collectively evaluated for impairment |
4,324
|
3,117
|
|
|
| Allowance for loan commitments |
176
|
119
|
143
|
151
|
| Total allowance for credit losses |
4,500
|
3,236
|
4,118
|
4,499
|
| Collectively evaluated for impairment |
439,480
|
391,140
|
|
|
| Acquired with deteriorated credit quality |
1,416
|
1,457
|
|
|
| Total loans |
440,896
|
392,597
|
|
|
| Commercial Real Estate - Improved Property [Member] |
|
|
|
|
| Financing Receivable, Allowance for Credit Losses [Line Items] |
|
|
|
|
| Allowance for loans individually evaluated for impairment |
387
|
388
|
|
|
| Allowance for loans collectively evaluated for impairment |
19,892
|
20,778
|
|
|
| Allowance for loan commitments |
21
|
26
|
17
|
17
|
| Total allowance for credit losses |
20,300
|
21,192
|
19,277
|
18,645
|
| Individually evaluated for impairment |
2,104
|
3,344
|
|
|
| Collectively evaluated for impairment |
2,567,367
|
2,593,393
|
|
|
| Acquired with deteriorated credit quality |
4,859
|
5,114
|
|
|
| Total loans |
2,574,330
|
2,601,851
|
|
|
| Commercial and Industrial [Member] |
|
|
|
|
| Financing Receivable, Allowance for Credit Losses [Line Items] |
|
|
|
|
| Allowance for loans collectively evaluated for impairment |
10,494
|
9,414
|
|
|
| Allowance for loan commitments |
176
|
173
|
157
|
188
|
| Total allowance for credit losses |
10,670
|
9,587
|
8,897
|
8,600
|
| Collectively evaluated for impairment |
1,117,607
|
1,124,544
|
|
|
| Acquired with deteriorated credit quality |
726
|
783
|
|
|
| Total loans |
1,118,333
|
1,125,327
|
|
|
| Deposit Overdraft [Member] |
|
|
|
|
| Financing Receivable, Allowance for Credit Losses [Line Items] |
|
|
|
|
| Allowance for loans collectively evaluated for impairment |
615
|
821
|
|
|
| Total allowance for credit losses |
615
|
821
|
586
|
760
|
| Residential Real Estate [Member] |
|
|
|
|
| Financing Receivable, Allowance for Credit Losses [Line Items] |
|
|
|
|
| Allowance for loans collectively evaluated for impairment |
3,252
|
3,206
|
|
|
| Allowance for loan commitments |
7
|
7
|
10
|
9
|
| Total allowance for credit losses |
3,259
|
3,213
|
4,120
|
4,115
|
| Collectively evaluated for impairment |
1,345,290
|
1,352,587
|
|
|
| Acquired with deteriorated credit quality |
703
|
714
|
|
|
| Total loans |
1,345,993
|
1,353,301
|
|
|
| Consumer [Member] |
|
|
|
|
| Financing Receivable, Allowance for Credit Losses [Line Items] |
|
|
|
|
| Allowance for loans collectively evaluated for impairment |
3,067
|
3,063
|
|
|
| Allowance for loan commitments |
41
|
37
|
42
|
44
|
| Total allowance for credit losses |
3,108
|
3,100
|
3,705
|
4,042
|
| Collectively evaluated for impairment |
319,561
|
339,163
|
|
|
| Acquired with deteriorated credit quality |
|
6
|
|
|
| Total loans |
319,561
|
339,169
|
|
|
| Home Equity [Member] |
|
|
|
|
| Financing Receivable, Allowance for Credit Losses [Line Items] |
|
|
|
|
| Allowance for loans collectively evaluated for impairment |
4,303
|
4,497
|
|
|
| Allowance for loan commitments |
208
|
212
|
179
|
162
|
| Total allowance for credit losses |
4,511
|
4,709
|
$ 3,906
|
$ 3,584
|
| Collectively evaluated for impairment |
523,425
|
529,196
|
|
|
| Total loans |
$ 523,425
|
$ 529,196
|
|
|