Securities Held to Maturity - Amortized Cost, Gross Unrecognized Gains and Losses and Fair Values of Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jun. 30, 2018
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	$ 598,318	$ 589,730
Gross Unrecognized Gains	391	141
Gross Unrecognized Losses	6,558	10,372
Securities held to maturity, estimated fair value	592,151	579,499
Mortgage-Backed Securities [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	434,237	433,953
Gross Unrecognized Gains	194	25
Gross Unrecognized Losses	4,598	8,223
Securities held to maturity, estimated fair value	429,833	425,755
Debt Securities [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	164,081	155,777
Gross Unrecognized Gains	197	116
Gross Unrecognized Losses	1,960	2,149
Fair Value	162,318	153,744
Debt Securities [Member] \| Obligations of State and Political Subdivisions [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	107,826	109,483
Gross Unrecognized Gains	172	79
Gross Unrecognized Losses	1,349	1,865
Fair Value	106,649	107,697
Debt Securities [Member] \| Subordinated Debt [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	56,255	46,294
Gross Unrecognized Gains	25	37
Gross Unrecognized Losses	611	284
Fair Value	55,669	46,047
Collateralized Mortgage Obligations Excluding Pass Through Securities [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	51,540	56,886
Gross Unrecognized Gains	27	6
Gross Unrecognized Losses	771	1,348
Securities held to maturity, estimated fair value	50,796	55,544
Residential Pass-Through Securities [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	182,335	200,622
Gross Unrecognized Gains	16	19
Gross Unrecognized Losses	2,689	4,005
Securities held to maturity, estimated fair value	179,662	196,636
Commercial Pass-Through Securities [Member]
Schedule Of Held To Maturity Securities [Line Items]
Amortized Cost	200,362	176,445
Gross Unrecognized Gains	151
Gross Unrecognized Losses	1,138	2,870
Securities held to maturity, estimated fair value	$ 199,375	$ 173,575

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

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

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

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Amortized cost of investment in debt security measured at amortized cost (held-to-maturity), with single maturity date and allocated without single maturity date.

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