Fair Value Measurements (Assets and Liabilities Reported on Consolidated Statements of Financial Condition at Fair Values) (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Securities available for sale:
Securities available for sale, at fair value	$ 984,206	$ 964,534
Derivative liabilities	15,700
Measured on a non-recurring basis:
Foreclosed assets	11,029	10,546
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	88,168	90,853
Derivative assets	0	0
Derivative liabilities	0	0
Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	896,038	873,681
Derivative assets	14,407	6,854
Derivative liabilities	15,565	6,745
Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Derivative assets	0	0
Derivative liabilities	0	0
US Treasury Obligations [Member]
Securities available for sale:
Securities available for sale, at fair value	8,047	8,004
US Treasury Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	8,047	8,004
US Treasury Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
US Treasury Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Agency Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	79,600	82,330
Agency Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Agency Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Mortgage-Backed Securities [Member]
Securities available for sale:
Securities available for sale, at fair value	886,641	863,861
Mortgage-Backed Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Mortgage-Backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	886,641	863,861
Mortgage-Backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
State And Municipal Obligations [Member]
Securities available for sale:
Securities available for sale, at fair value	4,322	4,308
State And Municipal Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
State And Municipal Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	4,322	4,308
State And Municipal Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Corporate Obligations [Member]
Securities available for sale:
Securities available for sale, at fair value	5,075	5,512
Corporate Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	0
Corporate Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	5,075
Corporate Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0
Equity Securities [Member]
Securities available for sale:
Securities available for sale, at fair value	521	519
Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	521	519
Equity Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Equity Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Recurring Basis [Member]
Securities available for sale:
Securities available for sale, at fair value	984,206	964,534
Derivative assets	14,407	6,854
Total assets at fair value	998,613	971,388
Derivative liabilities	15,565	6,745
Measured on a Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	88,168	90,853
Derivative assets	0	0
Total assets at fair value	88,168	90,853
Derivative liabilities	0	0
Measured on a Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	896,038	873,681
Derivative assets	14,407	6,854
Total assets at fair value	910,445	880,535
Derivative liabilities	15,565	6,745
Measured on a Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Derivative assets	0	0
Total assets at fair value	0	0
Derivative liabilities	0	0
Measured on a Recurring Basis [Member] | US Treasury Obligations [Member]
Securities available for sale:
Securities available for sale, at fair value	8,047	8,004
Measured on a Recurring Basis [Member] | US Treasury Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	8,047	8,004
Measured on a Recurring Basis [Member] | US Treasury Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Recurring Basis [Member] | US Treasury Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Recurring Basis [Member] | Agency Obligations [Member]
Securities available for sale:
Securities available for sale, at fair value	79,600	82,330
Measured on a Recurring Basis [Member] | Agency Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	79,600	82,330
Measured on a Recurring Basis [Member] | Agency Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Recurring Basis [Member] | Agency Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Recurring Basis [Member] | Mortgage-Backed Securities [Member]
Securities available for sale:
Securities available for sale, at fair value	886,641	863,861
Measured on a Recurring Basis [Member] | Mortgage-Backed Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Recurring Basis [Member] | Mortgage-Backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	886,641	863,861
Measured on a Recurring Basis [Member] | Mortgage-Backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Recurring Basis [Member] | State And Municipal Obligations [Member]
Securities available for sale:
Securities available for sale, at fair value	4,322	4,308
Measured on a Recurring Basis [Member] | State And Municipal Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Recurring Basis [Member] | State And Municipal Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	4,322	4,308
Measured on a Recurring Basis [Member] | State And Municipal Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Recurring Basis [Member] | Corporate Obligations [Member]
Securities available for sale:
Securities available for sale, at fair value	5,075	5,512
Measured on a Recurring Basis [Member] | Corporate Obligations [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	0
Measured on a Recurring Basis [Member] | Corporate Obligations [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	5,075	5,512
Measured on a Recurring Basis [Member] | Corporate Obligations [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0
Measured on a Recurring Basis [Member] | Equity Securities [Member]
Securities available for sale:
Securities available for sale, at fair value	521	519
Measured on a Recurring Basis [Member] | Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities available for sale:
Securities available for sale, at fair value	521	519
Measured on a Recurring Basis [Member] | Equity Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Recurring Basis [Member] | Equity Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities available for sale:
Securities available for sale, at fair value	0	0
Measured on a Non-Recurring Basis [Member]
Measured on a non-recurring basis:
Loans measured for impairment based on the fair value of the underlying collateral	10,136	9,481
Foreclosed assets	11,029	10,546
Fair value, Measured on a non-recurring basis	21,165	20,027
Measured on a Non-Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Measured on a non-recurring basis:
Loans measured for impairment based on the fair value of the underlying collateral	0	0
Foreclosed assets	0	0
Fair value, Measured on a non-recurring basis	0	0
Measured on a Non-Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member]
Measured on a non-recurring basis:
Loans measured for impairment based on the fair value of the underlying collateral	0	0
Foreclosed assets	0	0
Fair value, Measured on a non-recurring basis	0	0
Measured on a Non-Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member]
Measured on a non-recurring basis:
Loans measured for impairment based on the fair value of the underlying collateral	10,136	9,481
Foreclosed assets	11,029	10,546
Fair value, Measured on a non-recurring basis	$ 21,165	$ 20,027