Loans and the Allowance for Credit Losses - Schedule of Recorded Investment in Loans by Category (Detail) - USD ($)
$ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
| Financing Receivable, Recorded Investment [Line Items] |
|
|
| Total portfolio loans |
$ 6,322,538
|
$ 6,341,441
|
| Loans held for sale |
12,962
|
20,320
|
| Total loans |
6,335,500
|
6,361,761
|
| Commercial Real Estate - Land and Construction [Member] |
|
|
| Financing Receivable, Recorded Investment [Line Items] |
|
|
| Total portfolio loans |
440,896
|
392,597
|
| Commercial Real Estate - Improved Property [Member] |
|
|
| Financing Receivable, Recorded Investment [Line Items] |
|
|
| Total portfolio loans |
2,574,330
|
2,601,851
|
| Commercial and Industrial [Member] |
|
|
| Financing Receivable, Recorded Investment [Line Items] |
|
|
| Total portfolio loans |
1,118,333
|
1,125,327
|
| Commercial Real Estate [Member] |
|
|
| Financing Receivable, Recorded Investment [Line Items] |
|
|
| Total portfolio loans |
3,015,226
|
2,994,448
|
| Residential Real Estate [Member] |
|
|
| Financing Receivable, Recorded Investment [Line Items] |
|
|
| Total portfolio loans |
1,345,993
|
1,353,301
|
| Consumer [Member] |
|
|
| Financing Receivable, Recorded Investment [Line Items] |
|
|
| Total portfolio loans |
319,561
|
339,169
|
| Home Equity [Member] |
|
|
| Financing Receivable, Recorded Investment [Line Items] |
|
|
| Total portfolio loans |
$ 523,425
|
$ 529,196
|