Fair Value of Financial Instruments - Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Jun. 30, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value (amortized cost $1,671,935), net of allowance for credit losses of $0 at December 31, 2020	$ 1,695,893	$ 1,385,703
Investment securities held to maturity, amortized cost	29,549	32,556
Investment securities held to maturity	31,063	34,069
Interest rate contracts,assets	216	235
Interest rate contracts,liabilities	12,293	18,177
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value (amortized cost $1,671,935), net of allowance for credit losses of $0 at December 31, 2020	1,695,893	1,385,703
Carrying Amount [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	129,694	180,967
Investment securities available for sale, at fair value (amortized cost $1,671,935), net of allowance for credit losses of $0 at December 31, 2020	1,695,893	1,385,703
Investment securities held to maturity, amortized cost	29,549	32,556
Loans held-for-sale	12,601	20,789
Net loans receivable	4,765,248	4,461,070
FHLB Stock	45,578	58,654
Interest receivable	19,826	17,373
Interest rate contracts,assets	216	235
Deposits	5,312,613	4,430,282
Borrowings	865,651	1,173,165
Interest payable on deposits	327	395
Interest payable on borrowings	1,554	1,723
Interest rate contracts,liabilities	12,293	18,177
Fair Value [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	129,694	180,967
Investment securities available for sale, at fair value (amortized cost $1,671,935), net of allowance for credit losses of $0 at December 31, 2020	1,695,893	1,385,703
Investment securities held to maturity	31,063	34,069
Loans held-for-sale	13,129	21,550
Net loans receivable	4,808,589	4,462,232
Interest receivable	19,826	17,373
Interest rate contracts,assets	216	235
Deposits	5,325,183	4,449,877
Borrowings	899,960	1,215,529
Interest payable on deposits	327	395
Interest payable on borrowings	1,554	1,723
Interest rate contracts,liabilities	12,293	18,177
Fair Value [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash and cash equivalents	129,694	180,967
Interest receivable		4
Deposits	3,346,649	2,589,886
Interest payable on deposits	190	295
Fair Value [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities available for sale, at fair value (amortized cost $1,671,935), net of allowance for credit losses of $0 at December 31, 2020	1,695,893	1,385,703
Investment securities held to maturity	31,063	34,069
Loans held-for-sale	13,129	21,550
Interest receivable	4,301	4,154
Interest rate contracts,assets	216	235
Interest rate contracts,liabilities	12,293	18,177
Fair Value [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net loans receivable	4,808,589	4,462,232
Interest receivable	15,525	13,215
Deposits	1,978,534	1,859,991
Borrowings	899,960	1,215,529
Interest payable on deposits	137	100
Interest payable on borrowings	$ 1,554	$ 1,723

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Interest receivable fair value disclosure.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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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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