Allowance for Losses on Loans - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Sep. 30, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	$ 203,753	$ 177,207	$ 177,207
Charge-offs	(785)	(293)
Recoveries	554	406
Provision & Transfers	1,000	2,000
Ending Allowance	204,522	179,320	203,753
Unfunded commitments
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Provision & Transfers	1,000	2,000
Commercial loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	153,373	137,194	137,194
Charge-offs	(520)	(80)	(2,963)
Recoveries	16	84
Provision & Transfers	(401)	1,957
Ending Allowance	152,468	139,155	153,373
Commercial loans \| Multi-family
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	25,248	13,155	13,155
Charge-offs	0	0
Recoveries	0	0
Provision & Transfers	749	636
Ending Allowance	25,997	13,791	25,248
Commercial loans \| Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	39,210	28,842	28,842
Charge-offs	(163)	0	(203)
Recoveries	0	2
Provision & Transfers	(1,174)	163
Ending Allowance	37,873	29,007	39,210
Commercial loans \| Commercial & industrial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	58,748	58,773	58,773
Charge-offs	(357)	(62)	(2,611)
Recoveries	4	32
Provision & Transfers	2,079	2,093
Ending Allowance	60,474	60,836	58,748
Commercial loans \| Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	22,267	29,408	29,408
Charge-offs	0	0
Recoveries	0	0
Provision & Transfers	(1,364)	(545)
Ending Allowance	20,903	28,863	22,267
Commercial loans \| Land - acquisition & development
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	7,900	7,016	7,016
Charge-offs	0	(18)	(149)
Recoveries	12	50
Provision & Transfers	(691)	(390)
Ending Allowance	7,221	6,658	7,900
Consumer loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	50,380	40,013	40,013
Charge-offs	(265)	(213)	(662)
Recoveries	538	322
Provision & Transfers	1,401	43
Ending Allowance	52,054	40,165	50,380
Consumer loans \| Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	1,427	2,781	2,781
Charge-offs	0	0
Recoveries	0	0
Provision & Transfers	(208)	(519)
Ending Allowance	1,219	2,262	1,427
Consumer loans \| Single-family residential
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	40,523	28,029	28,029
Charge-offs	0	0	(144)
Recoveries	456	120
Provision & Transfers	1,138	407
Ending Allowance	42,117	28,556	40,523
Consumer loans \| Land - consumer lot loans
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	2,564	3,512	3,512
Charge-offs	0	0
Recoveries	0	9
Provision & Transfers	(37)	(176)
Ending Allowance	2,527	3,345	2,564
Consumer loans \| HELOC
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	3,049	2,859	2,859
Charge-offs	0	0
Recoveries	1	1
Provision & Transfers	108	113
Ending Allowance	3,158	2,973	3,049
Consumer loans \| Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Allowance	2,817	2,832	2,832
Charge-offs	(265)	(213)	(518)
Recoveries	81	192
Provision & Transfers	400	218
Ending Allowance	$ 3,033	$ 3,029	$ 2,817

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
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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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
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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