Borrowings - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Jun. 30, 2020
Debt Instrument [Line Items]
Other borrowings, sweep accounts	$ 0.0	$ 5.7
Mortgage-Backed Securities [Member]
Debt Instrument [Line Items]
Federal Home Loan Bank, advances, general debt obligations, disclosures, collateral pledged	155.6	155.3
Investment in Federal Home Loan Bank Stock [Member]
Debt Instrument [Line Items]
Federal Home Loan Bank, advances, general debt obligations, disclosures, collateral pledged	$ 3,090.0	$ 3,210.0

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- Definition

Amount of the collateral pledged in support of federal home loan bank advances outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

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- Definition

Amount of borrowings classified as other, maturing within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(a)(7))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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