Allowance for Loan Losses - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	$ 172,808	$ 171,300
Charge-offs	(228)	(677)
Recoveries	717	2,788
Provision & Transfers	3,500	(2,000)
Ending Allowance	176,797	171,411
Unfunded commitments
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision & Transfers	(1,000)	2,500
Commercial loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	133,476	125,375
Charge-offs	(82)	(574)
Recoveries	52	2,126
Provision & Transfers	4,836	910
Ending Allowance	138,282	127,837
Commercial loans \| Multi-family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	12,013	16,949
Charge-offs	0	0
Recoveries	0	0
Provision & Transfers	311	(956)
Ending Allowance	12,324	15,993
Commercial loans \| Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	25,814	23,437
Charge-offs	0	(529)
Recoveries	4	44
Provision & Transfers	1,562	2,770
Ending Allowance	27,380	25,722
Commercial loans \| Commercial & industrial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	57,210	45,957
Charge-offs	(82)	(43)
Recoveries	32	62
Provision & Transfers	6,713	1,255
Ending Allowance	63,873	47,231
Commercial loans \| Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	26,161	25,585
Charge-offs	0	0
Recoveries	0	2,000
Provision & Transfers	(28)	(2,819)
Ending Allowance	26,133	24,766
Commercial loans \| Land - acquisition & development
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	12,278	13,447
Charge-offs	0	(2)
Recoveries	16	20
Provision & Transfers	(3,722)	660
Ending Allowance	8,572	14,125
Consumer loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	39,332	45,925
Charge-offs	(146)	(103)
Recoveries	665	662
Provision & Transfers	(1,336)	(2,910)
Ending Allowance	38,515	43,574
Consumer loans \| Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	3,410	4,907
Charge-offs	0	0
Recoveries	0	0
Provision & Transfers	90	(1,188)
Ending Allowance	3,500	3,719
Consumer loans \| Single-family residential
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	25,518	30,978
Charge-offs	0	0
Recoveries	430	405
Provision & Transfers	(473)	(1,277)
Ending Allowance	25,475	30,106
Consumer loans \| Land - consumer lot loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	5,047	4,939
Charge-offs	0	(27)
Recoveries	0	5
Provision & Transfers	(905)	67
Ending Allowance	4,142	4,984
Consumer loans \| HELOC
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	2,482	2,390
Charge-offs	0	0
Recoveries	1	1
Provision & Transfers	105	(26)
Ending Allowance	2,588	2,365
Consumer loans \| Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	2,875	2,711
Charge-offs	(146)	(76)
Recoveries	234	251
Provision & Transfers	(153)	(486)
Ending Allowance	$ 2,810	$ 2,400

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (e)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

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- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

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- Definition

Financing Receivable, Allowance for Credit Losses, Excluding Accrued Interest, Provision and Transfers

+ References

No definition available.

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