Securities Available for Sale - Amortized Cost, Gross Unrealized Gains and Losses and Fair Values of Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	$ 548,354
Securities available for sale, Fair value	543,832	$ 590,562
Securities available for sale, Amortized Cost	674,594	729,406
Mortgage-backed securities, Gross Unrealized Gains	1,919	3,404
Mortgage-backed securities, Gross Unrealized Losses	9,911	7,725
Investment securities available for sale, at fair value	666,602	725,085
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	548,354	589,999
Securities available for sale, Gross Unrealized Gains	1,871	3,361
Securities available for sale, Gross Unrealized Losses	6,393	2,798
Securities available for sale, Fair value	543,832	590,562
Debt Securities [Member] \| U.S. Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	3,993	4,474
Securities available for sale, Gross Unrealized Losses	51	63
Securities available for sale, Fair value	3,942	4,411
Debt Securities [Member] \| Obligations of State and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	26,780	26,793
Securities available for sale, Gross Unrealized Gains	5	4
Securities available for sale, Gross Unrealized Losses	580	709
Securities available for sale, Fair value	26,205	26,088
Debt Securities [Member] \| Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	179,310	179,959
Securities available for sale, Gross Unrealized Gains	1,716	2,795
Securities available for sale, Gross Unrealized Losses	198	134
Securities available for sale, Fair value	180,828	182,620
Debt Securities [Member] \| Collateralized Loan Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	186,377	226,881
Securities available for sale, Gross Unrealized Gains	3	99
Securities available for sale, Gross Unrealized Losses	1,941	914
Securities available for sale, Fair value	184,439	226,066
Debt Securities [Member] \| Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	147,927	147,925
Securities available for sale, Gross Unrealized Gains	147	463
Securities available for sale, Gross Unrealized Losses	3,382	794
Securities available for sale, Fair value	144,692	147,594
Debt Securities [Member] \| Trust Preferred Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	3,967	3,967
Securities available for sale, Gross Unrealized Losses	241	184
Securities available for sale, Fair value	3,726	3,783
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	126,240	139,407
Mortgage-backed securities, Gross Unrealized Gains	48	43
Mortgage-backed securities, Gross Unrealized Losses	3,518	4,927
Investment securities available for sale, at fair value	122,770	134,523
Mortgage-Backed Securities [Member] \| Collateralized Mortgage Obligations Excluding Pass Through Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	23,959	25,651
Mortgage-backed securities, Gross Unrealized Losses	940	1,359
Investment securities available for sale, at fair value	23,019	24,292
Mortgage-Backed Securities [Member] \| Residential Pass-Through Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	94,418	105,810
Mortgage-backed securities, Gross Unrealized Gains	48	43
Mortgage-backed securities, Gross Unrealized Losses	2,548	3,494
Investment securities available for sale, at fair value	91,918	102,359
Mortgage-Backed Securities [Member] \| Commercial Pass-Through Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, Amortized Cost	7,863	7,946
Mortgage-backed securities, Gross Unrealized Losses	30	74
Investment securities available for sale, at fair value	$ 7,833	$ 7,872

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on 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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Amortized cost 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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-Section 45
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