| Loans - Analysis of Past Due Loans, Disaggregated by Loan Class, Non-PCI (Detail) - USD ($)
 | Mar. 31, 2020 | Dec. 31, 2019 | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | $ 4,543,636,000 | $ 4,610,147,000 | 
| Accruing 90 days or more past due loans receivable | 5,843,000 | 0 | 
| Non-PCI Loans |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 29,542,000 | 15,652,000 | 
| Current | 4,514,094,000 | 4,594,496,000 | 
| Total loans receivable | 4,543,636,000 | 4,610,147,000 | 
| Accruing 90 days or more past due loans receivable | 5,843,000 |  | 
| Non-PCI Loans | 30-59 Days Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 8,899,000 | 7,497,000 | 
| Non-PCI Loans | 60-89 Days Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 4,146,000 | 4,060,000 | 
| Non-PCI Loans | 90 Days or More Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 16,497,000 | 4,094,000 | 
| Real Estate |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | 3,566,305,000 | 3,628,505,000 | 
| Real Estate | Retail |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | 818,045,000 | 869,302,000 | 
| Real Estate | Hospitality |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | 884,511,000 | 922,288,000 | 
| Real Estate | Other |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | 1,420,824,000 | 1,358,432,000 | 
| Real Estate | Total commercial property loans |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | 3,123,380,000 | 3,150,022,000 | 
| Real Estate | Construction |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | 63,809,000 | 76,455,000 | 
| Real Estate | Residential property |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | 379,116,000 | 402,028,000 | 
| Real Estate | Non-PCI Loans |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 6,515,000 | 3,721,000 | 
| Current | 3,559,790,000 | 3,624,784,000 | 
| Total loans receivable | 3,566,306,000 | 3,628,505,000 | 
| Real Estate | Non-PCI Loans | Retail |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable |  | 249,000 | 
| Current | 818,045,000 | 869,053,000 | 
| Total loans receivable | 818,045,000 | 869,302,000 | 
| Real Estate | Non-PCI Loans | Hospitality |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable |  | 907,000 | 
| Current | 884,511,000 | 921,381,000 | 
| Total loans receivable | 884,511,000 | 922,288,000 | 
| Real Estate | Non-PCI Loans | Other |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 3,227,000 | 89,000 | 
| Current | 1,417,597,000 | 1,358,344,000 | 
| Total loans receivable | 1,420,824,000 | 1,358,432,000 | 
| Real Estate | Non-PCI Loans | Total commercial property loans |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 3,227,000 | 1,245,000 | 
| Current | 3,120,153,000 | 3,148,778,000 | 
| Total loans receivable | 3,123,380,000 | 3,150,022,000 | 
| Real Estate | Non-PCI Loans | Construction |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Current | 63,809,000 | 76,455,000 | 
| Total loans receivable | 63,809,000 | 76,455,000 | 
| Real Estate | Non-PCI Loans | Residential property |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 3,288,000 | 2,477,000 | 
| Current | 375,828,000 | 399,551,000 | 
| Total loans receivable | 379,116,000 | 402,028,000 | 
| Real Estate | Non-PCI Loans | 30-59 Days Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 1,239,000 | 1,504,000 | 
| Real Estate | Non-PCI Loans | 30-59 Days Past Due | Retail |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable |  | 6,000 | 
| Real Estate | Non-PCI Loans | 30-59 Days Past Due | Hospitality |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable |  | 907,000 | 
| Real Estate | Non-PCI Loans | 30-59 Days Past Due | Other |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 708,000 | 51,000 | 
| Real Estate | Non-PCI Loans | 30-59 Days Past Due | Total commercial property loans |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 708,000 | 964,000 | 
| Real Estate | Non-PCI Loans | 30-59 Days Past Due | Residential property |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 531,000 | 540,000 | 
| Real Estate | Non-PCI Loans | 60-89 Days Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 2,011,000 | 1,759,000 | 
| Real Estate | Non-PCI Loans | 60-89 Days Past Due | Retail |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable |  | 132,000 | 
| Real Estate | Non-PCI Loans | 60-89 Days Past Due | Other |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 1,418,000 |  | 
| Real Estate | Non-PCI Loans | 60-89 Days Past Due | Total commercial property loans |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 1,418,000 | 132,000 | 
| Real Estate | Non-PCI Loans | 60-89 Days Past Due | Residential property |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 593,000 | 1,627,000 | 
| Real Estate | Non-PCI Loans | 90 Days or More Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 3,265,000 | 458,000 | 
| Real Estate | Non-PCI Loans | 90 Days or More Past Due | Retail |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable |  | 111,000 | 
| Real Estate | Non-PCI Loans | 90 Days or More Past Due | Other |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 1,101,000 | 38,000 | 
| Real Estate | Non-PCI Loans | 90 Days or More Past Due | Total commercial property loans |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 1,101,000 | 149,000 | 
| Real Estate | Non-PCI Loans | 90 Days or More Past Due | Residential property |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 2,164,000 | 309,000 | 
| Commercial and Industrial |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | 472,714,000 | 484,093,000 | 
| Commercial and Industrial | Non-PCI Loans |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 10,151,000 | 911,000 | 
| Current | 462,563,000 | 483,183,000 | 
| Total loans receivable | 472,714,000 | 484,093,000 | 
| Accruing 90 days or more past due loans receivable | 5,520,000 |  | 
| Commercial and Industrial | Non-PCI Loans | 30-59 Days Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 349,000 | 635,000 | 
| Commercial and Industrial | Non-PCI Loans | 60-89 Days Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 318,000 | 133,000 | 
| Commercial and Industrial | Non-PCI Loans | 90 Days or More Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 9,484,000 | 143,000 | 
| Leases Receivable |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | 492,527,000 | 483,879,000 | 
| Leases Receivable | Non-PCI Loans |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 12,848,000 | 10,990,000 | 
| Current | 479,679,000 | 472,889,000 | 
| Total loans receivable | 492,527,000 | 483,879,000 | 
| Accruing 90 days or more past due loans receivable | 323,000 |  | 
| Leases Receivable | Non-PCI Loans | 30-59 Days Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 7,311,000 | 5,358,000 | 
| Leases Receivable | Non-PCI Loans | 60-89 Days Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 1,789,000 | 2,138,000 | 
| Leases Receivable | Non-PCI Loans | 90 Days or More Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 3,748,000 | 3,493,000 | 
| Consumer |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Total loans receivable | 12,090,000 | 13,670,000 | 
| Consumer | Non-PCI Loans |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | 28,000 | 30,000 | 
| Current | 12,062,000 | 13,639,000 | 
| Total loans receivable | 12,090,000 | 13,670,000 | 
| Consumer | Non-PCI Loans | 60-89 Days Past Due |  |  | 
| Financing Receivable, Past Due [Line Items] |  |  | 
| Past due loans receivable | $ 28,000 | $ 30,000 |