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FHLB Advances and Other Borrowings - Weighted Average Cost and Amount of Advances (Details) - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2018
Federal Home Loan Banks [Abstract] |  |  |
Weighted average interest rate, including cash flow hedges, at end of year | 1.79% | 2.49% | 2.66%
Weighted daily average interest rate, including cash flow hedges, during the year | 2.03% | 2.69% | 2.62%
Daily average of FHLB advances during the year | $ 2,532,596 | $ 2,533,890 | $ 2,384,795
Maximum amount of FHLB advances at any month end | 3,050,000 | 2,665,000 | 2,620,000
Interest expense during the year (including swap interest income and expense) | $ 51,445 | $ 68,190 | $ 62,452

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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 + Details
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- Definition The calculated weighted average interest rate for Federal Home Loan Bank advances for the period ended 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 + Details
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- Definition The maximum balance outstanding at any month end during the period 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 + Details
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- Definition Aggregate amount of interest expense on all borrowings. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.7,8) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details
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- Definition Federal Home Loan Bank, Advances, Activity for Year, Daily Average Balance of Agreements Outstanding + References No definition available. + Details
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