Fair Value Disclosures of Financial Assets and Liabilities - Balances of Assets Measured at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	$ 841,706	$ 817,115
Total assets measured at fair value on a recurring basis	841,706	817,115
Assets Measured at Fair Value on a Nonrecurring Basis	4,451	4,532
Loans held-for-sale	35,188	31,491
Total assets measured at fair value on a nonrecurring basis	81,078	42,911
Collateralized Mortgage Obligation ("CMO") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	162,078	97,557
Federal National Mortgage Association ("FNMA") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	319,325	367,128
Federal Home Loan Mortgage Corporation ("FHLMC") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	126,292	124,495
Government National Mortgage Association ("GNMA") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	84,409	95,592
U.S. Government and Agencies [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	37,020	32,158
State and Political Subdivisions [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	112,582	100,185
Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Nonrecurring Basis	4,451	4,532
Impaired Loans (Collateral Dependent) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Nonrecurring Basis	41,439	38,379
Quoted Prices in Active Markets for Identical Asset (Level 1) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total assets measured at fair value on a recurring basis
Loans held-for-sale
Total assets measured at fair value on a nonrecurring basis
Quoted Prices in Active Markets for Identical Asset (Level 1) [Member] | Collateralized Mortgage Obligation ("CMO") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Quoted Prices in Active Markets for Identical Asset (Level 1) [Member] | Federal National Mortgage Association ("FNMA") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Quoted Prices in Active Markets for Identical Asset (Level 1) [Member] | Federal Home Loan Mortgage Corporation ("FHLMC") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Quoted Prices in Active Markets for Identical Asset (Level 1) [Member] | Government National Mortgage Association ("GNMA") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Quoted Prices in Active Markets for Identical Asset (Level 1) [Member] | U.S. Government and Agencies [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Quoted Prices in Active Markets for Identical Asset (Level 1) [Member] | State and Political Subdivisions [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Quoted Prices in Active Markets for Identical Asset (Level 1) [Member] | Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Nonrecurring Basis
Quoted Prices in Active Markets for Identical Asset (Level 1) [Member] | Impaired Loans (Collateral Dependent) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Nonrecurring Basis
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total assets measured at fair value on a recurring basis	841,706	817,115
Loans held-for-sale	35,188
Total assets measured at fair value on a nonrecurring basis	35,188
Significant Other Observable Inputs (Level 2) [Member] | Collateralized Mortgage Obligation ("CMO") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	162,078	97,557
Significant Other Observable Inputs (Level 2) [Member] | Federal National Mortgage Association ("FNMA") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	319,324	367,128
Significant Other Observable Inputs (Level 2) [Member] | Federal Home Loan Mortgage Corporation ("FHLMC") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	126,292	124,495
Significant Other Observable Inputs (Level 2) [Member] | Government National Mortgage Association ("GNMA") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	84,410	95,592
Significant Other Observable Inputs (Level 2) [Member] | U.S. Government and Agencies [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	37,021	32,158
Significant Other Observable Inputs (Level 2) [Member] | State and Political Subdivisions [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis	112,581	100,185
Significant Other Observable Inputs (Level 2) [Member] | Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Nonrecurring Basis
Significant Other Observable Inputs (Level 2) [Member] | Impaired Loans (Collateral Dependent) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Nonrecurring Basis
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Total assets measured at fair value on a recurring basis
Loans held-for-sale
Total assets measured at fair value on a nonrecurring basis	45,890	42,911
Significant Unobservable Inputs (Level 3) [Member] | Collateralized Mortgage Obligation ("CMO") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Significant Unobservable Inputs (Level 3) [Member] | Federal National Mortgage Association ("FNMA") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Significant Unobservable Inputs (Level 3) [Member] | Federal Home Loan Mortgage Corporation ("FHLMC") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Significant Unobservable Inputs (Level 3) [Member] | Government National Mortgage Association ("GNMA") [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Significant Unobservable Inputs (Level 3) [Member] | U.S. Government and Agencies [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Significant Unobservable Inputs (Level 3) [Member] | State and Political Subdivisions [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Recurring Basis
Significant Unobservable Inputs (Level 3) [Member] | Other Real Estate Owned [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Nonrecurring Basis	4,451	4,532
Significant Unobservable Inputs (Level 3) [Member] | Impaired Loans (Collateral Dependent) [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets Measured at Fair Value on a Nonrecurring Basis	$ 41,439	$ 38,379