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Fair Value Measurements - Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands | Jun. 30, 2020 | Dec. 31, 2019
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | $ 1,037,489 | $ 1,138,352
Trading securities | 10,094 | 11,222
Impaired loans | 6,706 | 4,942
Measured on a recurring basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 1,037,489 | 1,138,352
Trading securities | 10,094 | 11,222
Equity securities | 214 | 250
Total | 1,047,797 | 1,149,824
Measured on a recurring basis | Mortgage-backed securities: |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 943,209 | 973,127
Measured on a recurring basis | Pass-through certificates, GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 289,153 | 329,407
Measured on a recurring basis | REMICs, GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 654,009 | 643,667
Measured on a recurring basis | Non-GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 47 | 53
Measured on a recurring basis | Municipal bonds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 254 | 299
Measured on a recurring basis | Corporate bonds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 94,026 | 164,926
Measured on a recurring basis | Other debt obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 94,280 | 165,225
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Trading securities | 10,094 | 11,222
Equity securities | 214 | 250
Total | 10,308 | 11,472
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-backed securities: |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pass-through certificates, GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | REMICs, GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Municipal bonds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate bonds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other debt obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 1,037,489 | 1,138,352
Trading securities | 0 | 0
Equity securities | 0 | 0
Total | 1,037,489 | 1,138,352
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Mortgage-backed securities: |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 943,209 | 973,127
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Pass-through certificates, GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 289,153 | 329,407
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) | REMICs, GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 654,009 | 643,667
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Non-GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 47 | 53
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Municipal bonds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 254 | 299
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Corporate bonds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 94,026 | 164,926
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Other debt obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 94,280 | 165,225
Measured on a recurring basis | Significant Unobservable Inputs (Level 3) |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Trading securities | 0 | 0
Equity securities | 0 | 0
Total | 0 | 0
Measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Mortgage-backed securities: |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Pass-through certificates, GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Significant Unobservable Inputs (Level 3) | REMICs, GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Non-GSE |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Municipal bonds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Corporate bonds |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Other debt obligations |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Debt securities available-for-sale | 0 | 0
Measured on a non-recurring basis |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Total | 6,706 | 4,942
Measured on a non-recurring basis | Real Estate |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 6,692 | 4,927
Measured on a non-recurring basis | Real Estate | Commercial real estate |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 6,125 | 4,871
Measured on a non-recurring basis | Real Estate | One-to-Four Family |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 517 |
Measured on a non-recurring basis | Real Estate | Multifamily |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 22 | 26
Measured on a non-recurring basis | Real Estate | Home Equity and Lines of Credit |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 28 | 30
Measured on a non-recurring basis | Commercial and Industrial |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 14 | 15
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Total | 0 | 0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real Estate |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 | 0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real Estate | Commercial real estate |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 | 0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real Estate | One-to-Four Family |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 |
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real Estate | Multifamily |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 | 0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real Estate | Home Equity and Lines of Credit |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 | 0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial and Industrial |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 | 0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Total | 0 | 0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Real Estate |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 | 0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Real Estate | Commercial real estate |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 | 0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Real Estate | One-to-Four Family |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 |
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Real Estate | Multifamily |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 | 0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Real Estate | Home Equity and Lines of Credit |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 | 0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Commercial and Industrial |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 0 | 0
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Total | 6,706 | 4,942
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Real Estate |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 6,692 | 4,927
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Real Estate | Commercial real estate |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 6,125 | 4,871
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Real Estate | One-to-Four Family |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 517 |
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Real Estate | Multifamily |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 22 | 26
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Real Estate | Home Equity and Lines of Credit |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | 28 | 30
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Commercial and Industrial |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Impaired loans | $ 14 | $ 15

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