Fair Value Measurement - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	$ 517,388	$ 511,006
Fair Value, Measurements, Recurring [Member] | US Treasury and Government Sponsored Entities Securities [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	230,716	222,293
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	458	445
Fair Value, Measurements, Recurring [Member] | Mortgage-Backed GSE Securities: Residential [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	286,214	288,268
Fair Value, Measurements, Recurring [Member] | Mortgage Servicing Assets [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	103
Fair Value, Measurements, Recurring [Member] | Interest Rate Caps [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	419	546
Fair Value, Measurements, Recurring [Member] | Purchased Certificate of Deposit Option [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	267	155
Fair Value, Measurements, Recurring [Member] | Written Certificate of Deposit Option [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	267	155
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government Sponsored Entities Securities [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	458	445
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-Backed GSE Securities: Residential [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage Servicing Assets [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Caps [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Purchased Certificate of Deposit Option [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Written Certificate of Deposit Option [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government Sponsored Entities Securities [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	230,716	222,293
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-Backed GSE Securities: Residential [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	286,214	288,268
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage Servicing Assets [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	103
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Caps [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Purchased Certificate of Deposit Option [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	267	155
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Written Certificate of Deposit Option [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	267	155
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | US Treasury and Government Sponsored Entities Securities [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-Backed GSE Securities: Residential [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage Servicing Assets [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Caps [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value	419	546
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Purchased Certificate of Deposit Option [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Written Certificate of Deposit Option [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Available for sale securities, Fair value