Fair Value of Financial Instruments - Schedule of Assets Measured At Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019
Assets:
Securities available for sale, Fair value	$ 666,377	$ 544,333
Mortgage-backed securities available for sale	565,314	169,930
Securities available for sale	1,231,691	714,263
Interest rate swaps and caps	2,430	3,856
Total assets	1,234,121	718,119
Liabilities:
Interest rate swaps, liabilities	369	140
Total liabilities	369	140
Interest Rate Swaps and Caps [Member]
Assets:
Interest rate swaps and caps	2,430
Interest Rate Swaps [Member]
Assets:
Interest rate swaps and caps	1,012	3,856
Liabilities:
Interest rate swaps, liabilities	369	140
Debt Securities [Member]
Assets:
Securities available for sale, Fair value	666,377	544,333
Debt Securities [Member] \| U.S. Agency Securities [Member]
Assets:
Securities available for sale, Fair value	694	3,678
Debt Securities [Member] \| Obligations of State and Political Subdivisions [Member]
Assets:
Securities available for sale, Fair value	91,050	26,951
Debt Securities [Member] \| Asset-backed Securities [Member]
Assets:
Securities available for sale, Fair value	181,068	179,313
Debt Securities [Member] \| Collateralized Loan Obligations [Member]
Assets:
Securities available for sale, Fair value	198,549	208,611
Debt Securities [Member] \| Corporate Bonds [Member]
Assets:
Securities available for sale, Fair value	191,241	122,024
Debt Securities [Member] \| Trust Preferred Securities [Member]
Assets:
Securities available for sale, Fair value	3,775	3,756
Collateralized Mortgage Obligations Excluding Pass Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	63,594	21,390
Residential Pass-Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	202,858	44,303
Commercial Pass-Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	298,862	104,237
Interest Rate Swaps [Member]
Assets:
Interest rate swaps and caps		3,856
Liabilities:
Interest rate swaps, liabilities		140
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Securities available for sale, Fair value	665,377	543,333
Mortgage-backed securities available for sale	565,314	169,930
Securities available for sale	1,230,691	713,263
Total assets	1,233,121	717,119
Liabilities:
Total liabilities	369	140
Significant Other Observable Inputs (Level 2) [Member] \| Interest Rate Swaps and Caps [Member]
Assets:
Interest rate swaps and caps	2,430
Significant Other Observable Inputs (Level 2) [Member] \| Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps, liabilities	369
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| U.S. Agency Securities [Member]
Assets:
Securities available for sale, Fair value	694	3,678
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Obligations of State and Political Subdivisions [Member]
Assets:
Securities available for sale, Fair value	91,050	26,951
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Asset-backed Securities [Member]
Assets:
Securities available for sale, Fair value	181,068	179,313
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Collateralized Loan Obligations [Member]
Assets:
Securities available for sale, Fair value	198,549	208,611
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Corporate Bonds [Member]
Assets:
Securities available for sale, Fair value	191,241	122,024
Significant Other Observable Inputs (Level 2) [Member] \| Debt Securities [Member] \| Trust Preferred Securities [Member]
Assets:
Securities available for sale, Fair value	2,775	2,756
Significant Other Observable Inputs (Level 2) [Member] \| Collateralized Mortgage Obligations Excluding Pass Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	63,594	21,390
Significant Other Observable Inputs (Level 2) [Member] \| Residential Pass-Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	202,858	44,303
Significant Other Observable Inputs (Level 2) [Member] \| Commercial Pass-Through Securities [Member]
Assets:
Mortgage-backed securities available for sale	298,862	104,237
Significant Other Observable Inputs (Level 2) [Member] \| Interest Rate Swaps [Member]
Assets:
Interest rate swaps and caps		3,856
Liabilities:
Interest rate swaps, liabilities		140
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Securities available for sale, Fair value	1,000	1,000
Securities available for sale	1,000	1,000
Total assets	1,000	1,000
Significant Unobservable Inputs (Level 3) [Member] \| Debt Securities [Member] \| Trust Preferred Securities [Member]
Assets:
Securities available for sale, Fair value	$ 1,000	$ 1,000

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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