Fair Value Measurements (Assets and Liabilities) (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	$ 948,614	$ 976,919
Equity securities	806	825
Derivative liabilities	139,000
Foreclosed assets	3,272	2,715
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
Equity securities	806	825
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:	948,614	976,919
Equity securities	0	0
Derivative assets	118,706	39,305
Derivative liabilities	129,233	39,356
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
Mortgage-Backed Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	916,985	947,430
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:	916,985	947,430
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
State And Municipal Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	4,096	4,079
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:	4,096	4,079
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:	27,533	25,410
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:	27,533	25,410
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:	948,614	976,919
Equity securities	806	825
Derivative assets	118,706	39,305
Total assets at fair value	1,068,126	1,017,049
Derivative liabilities	129,233	39,356
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	0
Equity securities	806	825
Derivative assets	0	0
Total assets at fair value	806	825
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:	948,614	976,919
Equity securities	0	0
Derivative assets	118,706	39,305
Total assets at fair value	1,067,320	1,016,224
Derivative liabilities	129,233	39,356
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 | Mortgage-Backed Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	916,985	947,430
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:	916,985	947,430
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 | State And Municipal Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale debt securities:	4,096	4,079
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:	4,096	4,079
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:	27,533	25,410
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:	27,533	25,410
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	20,222	23,118
Loans measured for impairment based on the fair value of the underlying collateral	16,950	20,403
Foreclosed assets	3,272	2,715
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	20,222	23,118
Loans measured for impairment based on the fair value of the underlying collateral	16,950	20,403
Foreclosed assets	$ 3,272	$ 2,715