Fair Value (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	$ 2,434	$ 3,706
Available-for-sale Securities	545,484	547,864
Performing troubled debt restructurings individually evaluated for impairment	160,041	170,473
Allowance on performing troubled debt restructurings individually evaluated for impairment based on the present value of cash flows	13,657	13,505
Real estate owned, net	2,728	2,163
Cost to dispose related to properties measured at fair value included in Consolidated Statements of Condition	309	146
Present Value of Cash Flows \| Troubled Debt Restructuring \| Performing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowance on performing troubled debt restructurings individually evaluated for impairment based on the present value of cash flows	13,580	13,399
Subject To Pending Agency Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	0	0
Portion at Other than Fair Value \| Present Value of Cash Flows \| Troubled Debt Restructuring \| Performing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Performing troubled debt restructurings individually evaluated for impairment	98,475	98,875
Allowance on performing troubled debt restructurings individually evaluated for impairment based on the present value of cash flows	13,580	13,399
Portion at Other than Fair Value \| Original Or Adjusted Cost Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate owned, net	762	1,322
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	2,434	3,706
Available-for-sale Securities	545,484	547,864
Fair Value, Inputs, Level 2 \| Portion at Other than Fair Value \| Carried At Cost
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	2,337	3,666
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held for sale	0	0
Available-for-sale Securities	0	0
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities carried at fair value	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| U.S. Government Obligations \| Market Approach Valuation Technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	545,484	547,864
Fair Value, Measurements, Nonrecurring \| Fair Value, Inputs, Level 3 \| Market Approach Valuation Technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Real estate owned, net	$ 2,275	$ 987

The estimated cost to sell properties, acquired through foreclosure, which are measured at fair value.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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Fair value of financial and nonfinancial obligations.

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Fair value portion of mortgage loans held-for-sale.

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Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

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