Fair Value of Financial Instruments - Schedule of Assets Measured At Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Jun. 30, 2020
Assets:
Securities available for sale, Fair value	$ 700,952
Mortgage-backed securities available for sale	1,026,004	$ 819,148
Securities available for sale	1,695,893	1,385,703
Interest rate contracts	216	235
Total assets	1,696,109	1,385,938
Liabilities:
Interest rate contracts	12,293	18,177
Total liabilities	12,293	18,177
Interest Rate Contract [Member]
Assets:
Interest rate contracts	216	235
Liabilities:
Interest rate contracts	12,293	18,177
Debt Securities [Member]
Assets:
Securities available for sale, Fair value	669,889	566,555
Debt Securities [Member] \| Obligations of State and Political Subdivisions [Member]
Assets:
Securities available for sale, Fair value	47,763	54,054
Debt Securities [Member] \| Asset-backed Securities [Member]
Assets:
Securities available for sale, Fair value	255,407	172,447
Debt Securities [Member] \| Collateralized Loan Obligations [Member]
Assets:
Securities available for sale, Fair value	196,685	193,788
Debt Securities [Member] \| Corporate Bonds [Member]
Assets:
Securities available for sale, Fair value	167,168	143,639
Debt Securities [Member] \| Trust Preferred Securities [Member]
Assets:
Securities available for sale, Fair value	2,866	2,627
Collateralized Mortgage Obligations Excluding Pass Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	20,510	30,903
Residential Pass-Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	705,991	561,954
Commercial Pass-Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	299,503	226,291
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Mortgage-backed securities available for sale	1,026,004	819,148
Securities available for sale	1,695,893	1,385,703
Total assets	1,696,109	1,385,938
Liabilities:
Total liabilities	12,293	18,177
Significant Other Observable Inputs (Level 2) [Member] \| Interest Rate Contract [Member]
Assets:
Interest rate contracts	216	235
Liabilities:
Interest rate contracts	12,293	18,177
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member]
Assets:
Securities available for sale, Fair value	669,889	566,555
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Obligations of State and Political Subdivisions [Member]
Assets:
Securities available for sale, Fair value	47,763	54,054
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Asset-backed Securities [Member]
Assets:
Securities available for sale, Fair value	255,407	172,447
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Collateralized Loan Obligations [Member]
Assets:
Securities available for sale, Fair value	196,685	193,788
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Corporate Bonds [Member]
Assets:
Securities available for sale, Fair value	167,168	143,639
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Trust Preferred Securities [Member]
Assets:
Securities available for sale, Fair value	2,866	2,627
Significant Other Observable Inputs (Level 2) [Member] \| Collateralized Mortgage Obligations Excluding Pass Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	20,510	30,903
Significant Other Observable Inputs (Level 2) [Member] \| Residential Pass-Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	705,991	561,954
Significant Other Observable Inputs (Level 2) [Member] \| Commercial Pass-Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	$ 299,503	$ 226,291

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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