Fair Value Measurements (Assets and Liabilities) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	$ 1,216,936	$ 1,105,489
Equity securities	1,026	971
Derivative liabilities	38,500
Foreclosed assets	3,554	4,475
Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	1,009
Equity securities	1,026	971
Derivative assets	0	0
Derivative liabilities	0	0
Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	1,216,936	1,104,480
Equity securities	0	0
Derivative assets	76,542	101,079
Derivative liabilities	78,228	109,148
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Equity securities	0	0
Derivative assets	0	0
Derivative liabilities	0	0
Agency Obligations | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:		1,009
Agency Obligations | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:		0
Agency Obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:		0
Mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	1,060,152	938,413
Mortgage-backed securities | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Mortgage-backed securities | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	1,060,152	938,413
Mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	49,205	53,830
Asset-backed securities | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:
Asset-backed securities | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	49,205	53,830
Asset-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:
State And Municipal Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	68,934	71,258
State And Municipal Obligations | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
State And Municipal Obligations | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	68,934	71,258
State And Municipal Obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Corporate Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	38,645	40,979
Corporate Obligations | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Corporate Obligations | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	38,645	40,979
Corporate Obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Measured on a Recurring Basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	1,216,936	1,105,489
Equity securities	1,026	971
Derivative assets	76,542	101,079
Total assets at fair value	1,294,504	1,207,539
Derivative liabilities	78,228	109,148
Measured on a Recurring Basis | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	1,009
Equity securities	1,026	971
Derivative assets	0	0
Total assets at fair value	1,026	1,980
Derivative liabilities	0	0
Measured on a Recurring Basis | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	1,216,936	1,104,480
Equity securities	0	0
Derivative assets	76,542	101,079
Total assets at fair value	1,293,478	1,205,559
Derivative liabilities	78,228	109,148
Measured on a Recurring Basis | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Equity securities	0	0
Derivative assets	0	0
Total assets at fair value	0	0
Derivative liabilities	0	0
Measured on a Recurring Basis | Agency Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:		1,009
Measured on a Recurring Basis | Agency Obligations | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:		1,009
Measured on a Recurring Basis | Agency Obligations | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:		0
Measured on a Recurring Basis | Agency Obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:		0
Measured on a Recurring Basis | Mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	1,060,152	938,413
Measured on a Recurring Basis | Mortgage-backed securities | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Measured on a Recurring Basis | Mortgage-backed securities | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	1,060,152	938,413
Measured on a Recurring Basis | Mortgage-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Measured on a Recurring Basis | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	49,205	53,830
Measured on a Recurring Basis | Asset-backed securities | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0
Measured on a Recurring Basis | Asset-backed securities | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	49,205	53,830
Measured on a Recurring Basis | Asset-backed securities | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0
Measured on a Recurring Basis | State And Municipal Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	68,934	71,258
Measured on a Recurring Basis | State And Municipal Obligations | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Measured on a Recurring Basis | State And Municipal Obligations | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	68,934	71,258
Measured on a Recurring Basis | State And Municipal Obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Measured on a Recurring Basis | Corporate Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	38,645	40,979
Measured on a Recurring Basis | Corporate Obligations | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Measured on a Recurring Basis | Corporate Obligations | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	38,645	40,979
Measured on a Recurring Basis | Corporate Obligations | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	0	0
Measured on a Non-Recurring Basis
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets at fair value	33,674	30,725
Loans measured for impairment based on the fair value of the underlying collateral	30,120	26,250
Foreclosed assets	3,554	4,475
Measured on a Non-Recurring Basis | Quoted Prices in Active  Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets at fair value	0	0
Loans measured for impairment based on the fair value of the underlying collateral	0	0
Foreclosed assets	0	0
Measured on a Non-Recurring Basis | Significant Other Observable  Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets at fair value	0	0
Loans measured for impairment based on the fair value of the underlying collateral	0	0
Foreclosed assets	0	0
Measured on a Non-Recurring Basis | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets at fair value	33,674	30,725
Loans measured for impairment based on the fair value of the underlying collateral	30,120	26,250
Foreclosed assets	$ 3,554	$ 4,475