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Federal Home Loan Bank Advances - Additional Information (Detail) $ in Millions	3 Months Ended
	Dec. 31, 2020 USD ($) advance	Sep. 30, 2020	Dec. 31, 2019
Federal Home Loan Bank, Advances [Line Items]
Weighted-average rates of FHLB advances	1.32%		2.19%
Modifications, amount	$ 500.0
Modifications, number of contracts | advance	4
Weighted average interest rate	1.28%	2.00%
Modifications, unamortized prepayment fees	$ 30.0
FHLB Advances
Federal Home Loan Bank, Advances [Line Items]
Percentage of borrowings collateralized by investment securities and residential real estate loans	140.00%

X

- Definition

Advances From Federal Home Loan Banks, Modifications, Amount

+ References

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- Definition

Advances From Federal Home Loan Banks, Modifications, Number Of Contracts

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- Definition

Advances From Federal Home Loan Banks, Modifications, Unamortized Prepayment Fees

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- Definition

Amount of collateral pledged as a percentage of outstanding secured debt.

+ References

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- Definition

The calculated weighted average interest rate for Federal Home Loan Bank advances outstanding as of the Balance Sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13(3)(a))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Weighted average interest rate on advances made and reported by Federal Home Loan Bank (FHLBank).

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