FAIR VALUE - Financial Assets and Liabilities at Dates Indicated that Were Accounted for or Disclosed at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	$ 78,294	$ 53,701
Investments available-for-sale (at fair value)	1,348,021	1,073,333
Residential mortgage loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	75,500	52,600
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	1,348,021	1,073,333
Total assets	1,435,498	1,129,541
Total liabilities	(9,183)	(2,507)
Fair Value, Measurements, Recurring | Residential mortgage loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	78,294	53,701
Fair Value, Measurements, Recurring | U.S. treasuries and government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	43,297	258,495
Fair Value, Measurements, Recurring | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	390,367	233,649
Fair Value, Measurements, Recurring | Mortgage-backed and asset-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	904,432	570,759
Fair Value, Measurements, Recurring | Corporate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	9,925	9,552
Fair Value, Measurements, Recurring | Trust preferred
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		310
Fair Value, Measurements, Recurring | Marketable equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		568
Fair Value, Measurements, Recurring | Total swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements	9,183	2,507
Interest rate swap agreements	(9,183)	(2,507)
Fair Value, Measurements, Recurring | Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		1,072,765
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Total assets	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Residential mortgage loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. treasuries and government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-backed and asset-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Trust preferred
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Marketable equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Total swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements	0	0
Interest rate swap agreements	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	1,338,096	1,063,471
Total assets	1,425,573	1,119,679
Total liabilities	(9,183)	(2,507)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Residential mortgage loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	78,294	53,701
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. treasuries and government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	43,297	258,495
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	390,367	233,649
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-backed and asset-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	904,432	570,759
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Trust preferred
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Marketable equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		568
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Total swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements	9,183	2,507
Interest rate swap agreements	(9,183)	(2,507)
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		1,062,903
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	9,925	9,862
Total assets	9,925	9,862
Total liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Residential mortgage loans held for sale
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Residential mortgage loans held for sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | U.S. treasuries and government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Mortgage-backed and asset-backed
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)	9,925	9,552
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Trust preferred
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		310
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Marketable equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Total swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swap agreements	0	0
Interest rate swap agreements	$ 0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Debt Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments available-for-sale (at fair value)		$ 9,862