Mortgage Loans - Loan Commitments and Related Derivatives Textual (Details) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
Interest rate lock commitments [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 4,000.0	$ 1,500.0
Best-efforts whole loan delivery commitments [Member]
Derivative [Line Items]
Derivative, Notional Amount	23.5	88.8
Hedging Instruments Related To IRLCs [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 3,800.0	$ 1,400.0

Nominal or face amount used to calculate payment on derivative.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI https://asc.fasb.org/extlink&oid=125515794&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=125515794&loc=SL5579245-113959

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant