Borrowings - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2022	Jun. 30, 2021
Mortgage-Backed Securities [Member]
Debt Instrument [Line Items]
Federal Home Loan Bank, advances, general debt obligations, disclosures, collateral pledged	$ 178.0	$ 170.1
Investment in Federal Home Loan Bank Stock [Member]
Debt Instrument [Line Items]
Federal Home Loan Bank, advances, general debt obligations, disclosures, collateral pledged	$ 3,580.0	$ 3,270.0

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

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=123599511&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

Name:	us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant