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

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Amortized cost excluding accrued interest, before allowance for credit loss, fee, and loan in process, of financing receivable. Excludes net investment in lease.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Amount of undisbursed portion of financing receivable balance. Excludes financing receivable covered under loss sharing agreement.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount of unamortized loan commitment, origination, and other costs (fees) and purchase premium (discount) on financing receivable recognized as adjustment to yield. Excludes financing receivable covered under loss sharing agreement.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Financing Receivable, Charges to Allowance, Loans in Process and Deferred Fees

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Loans Receivable - Schedule of Loans Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025	Sep. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Sep. 30, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 21,443,205		$ 21,274,392
Ratio of loan type to all loans	100.00%		100.00%
Allowance for credit losses on loans	$ 201,950	$ 199,539	$ 199,720	$ 202,709	$ 204,522	$ 203,753
Loans in process	1,063,129		773,606
Net deferred fees, costs and discounts	211,143		212,448
Total loan contra accounts	1,476,222		1,185,774
Net loans	19,966,983		20,088,618
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 13,371,169		$ 12,651,754
Ratio of loan type to all loans	62.40%		59.50%
Allowance for credit losses on loans	$ 160,492	155,747	$ 152,134	151,281	152,468	153,373
Commercial loans \| Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 4,750,092		$ 4,718,480
Ratio of loan type to all loans	22.20%		22.20%
Allowance for credit losses on loans	$ 25,923	25,843	$ 25,953	26,556	25,997	25,248
Commercial loans \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 3,670,285		$ 3,604,600
Ratio of loan type to all loans	17.10%		16.90%
Allowance for credit losses on loans	$ 41,503	42,105	$ 41,988	38,469	37,873	39,210
Commercial loans \| Commercial & industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 2,798,568		$ 2,392,685
Ratio of loan type to all loans	13.10%		11.30%
Allowance for credit losses on loans	$ 68,662	62,102	$ 59,163	60,147	60,474	58,748
Commercial loans \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 1,955,180		$ 1,756,890
Ratio of loan type to all loans	9.10%		8.30%
Allowance for credit losses on loans	$ 16,712	18,475	$ 18,136	19,406	20,903	22,267
Commercial loans \| Land - acquisition & development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 197,044		$ 179,099
Ratio of loan type to all loans	0.90%		0.80%
Allowance for credit losses on loans	$ 7,692	7,222	$ 6,894	6,703	7,221	7,900
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 8,072,036		$ 8,622,638
Ratio of loan type to all loans	37.60%		40.50%
Allowance for credit losses on loans	$ 41,458	43,792	$ 47,586	51,428	52,054	50,380
Consumer loans \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 69,520		$ 150,237
Ratio of loan type to all loans	0.30%		0.70%
Allowance for credit losses on loans	$ 302	455	$ 610	1,076	1,219	1,427
Consumer loans \| Single-family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 7,618,273		$ 8,053,771
Ratio of loan type to all loans	35.50%		37.80%
Allowance for credit losses on loans	$ 33,679	35,847	$ 38,880	40,963	42,117	40,523
Consumer loans \| Land - consumer lot loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 77,275		$ 89,298
Ratio of loan type to all loans	0.40%		0.40%
Allowance for credit losses on loans	$ 1,821	1,958	$ 2,104	2,415	2,527	2,564
Consumer loans \| HELOC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 252,319		$ 267,871
Ratio of loan type to all loans	1.20%		1.30%
Allowance for credit losses on loans	$ 2,850	2,951	$ 3,069	3,257	3,158	3,049
Consumer loans \| Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans	$ 54,649		$ 61,461
Ratio of loan type to all loans	0.20%		0.30%
Allowance for credit losses on loans	$ 2,806	$ 2,581	$ 2,923	$ 3,717	$ 3,033	$ 2,817