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Derivatives and Hedging Activities - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Derivative [Line Items]
Gain (loss) on termination of hedging derivatives	$ 14,110	$ 0	$ 14,110	$ 0
Interest Rate Swap One | Cash flow hedging | Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of derivative terminated			$ 200,000
Effective interest rate of derivative terminated			1.37%
Interest Rate Swap | Minimum
Derivative [Line Items]
Derivative, maturities			1 year
Interest Rate Swap | Maximum
Derivative [Line Items]
Derivative, maturities			10 years
Interest Rate Swap | Weighted average
Derivative [Line Items]
Derivative, maturities			6 years 8 months 12 days
Interest Rate Swap Two | Cash flow hedging | Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of derivative terminated			$ 200,000
Effective interest rate of derivative terminated			0.79%
Interest Rate Swap Three | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of derivative terminated			$ 150,000
Effective interest rate of derivative terminated			2.91%

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- Definition

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

Period remaining until the derivative contract matures, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Change in carrying amount of the indemnification asset relating to loss sharing agreements with the Federal Deposit Insurance Corporation (FDIC). The change includes for example, but is not limited to, acquisitions, additional estimated losses, disposals, cash payments, accretion of discount and write-offs, net of recoveries.

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