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Fair Value Measurements - Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale	$ 1,097,423	$ 1,264,805
Trading securities	12,743	12,291
Individually evaluated loans	4,705	5,325
Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale	1,097,423	1,264,805
Trading securities	12,743	12,291
Equity securities	219	253
Total	1,110,385	1,277,349
Measured on a recurring basis | U.S. Government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale	2,754	3,158
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	970,145	1,172,312
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	229,767	281,343
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	740,378	890,965
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		4
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	78	123
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	124,446	88,418
Measured on a recurring basis | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale		794
Measured on a recurring basis | Other debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale	124,524	89,335
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	12,743	12,291
Equity securities	219	253
Total	12,962	12,544
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Government agency 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) | 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
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) | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale		0
Measured on a recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other debt 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 Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale	1,097,423	1,264,805
Trading securities	0	0
Equity securities	0	0
Total	1,097,423	1,264,805
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) | U.S. Government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale	2,754	3,158
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	970,145	1,172,312
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	229,767	281,343
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	740,378	890,965
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		4
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	78	123
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	124,446	88,418
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale		794
Measured on a recurring basis | Significant Other Observable Inputs (Level 2) | Other debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale	124,524	89,335
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) | U.S. Government agency 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) | 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
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) | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available-for-sale		0
Measured on a recurring basis | Significant Unobservable Inputs (Level 3) | Other debt securities
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	4,805	5,325
Measured on a non-recurring basis | Real estate loans:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	4,691	5,312
Measured on a non-recurring basis | Real estate loans: | Commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	3,799	5,268
Measured on a non-recurring basis | Real estate loans: | One-to-Four Family
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	854
Measured on a non-recurring basis | Real estate loans: | Multifamily
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	9	16
Measured on a non-recurring basis | Real estate loans: | Home equity and lines of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	29	28
Measured on a non-recurring basis | Commercial and industrial loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	14	13
Measured on a non-recurring basis | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	100
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 loans:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0	0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real estate loans: | Commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0	0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real estate loans: | One-to-Four Family
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real estate loans: | Multifamily
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0	0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Real estate loans: | Home equity and lines of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0	0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial and industrial loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0	0
Measured on a non-recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	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 loans:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0	0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Real estate loans: | Commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0	0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Real estate loans: | One-to-Four Family
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Real estate loans: | Multifamily
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0	0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Real estate loans: | Home equity and lines of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0	0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Commercial and industrial loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	0	0
Measured on a non-recurring basis | Significant Other Observable Inputs (Level 2) | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	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	4,805	5,325
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Real estate loans:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	4,691	5,312
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Real estate loans: | Commercial real estate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	3,799	5,268
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Real estate loans: | One-to-Four Family
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	854
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Real estate loans: | Multifamily
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	9	16
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Real estate loans: | Home equity and lines of credit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	29	28
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Commercial and industrial loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	14	$ 13
Measured on a non-recurring basis | Significant Unobservable Inputs (Level 3) | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually evaluated loans	$ 100

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

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No definition available.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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