LHFI and ACL, LHFI - Past Due Modifications Related to Loans Held For Investment (Details) - Troubled Debt Restructurings [Member] - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	$ 41,090	$ 8,875
30 Days or More Past Due [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	990	114
Past Due 60 to 89 Days [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	1,462	50
Past Due 90 Days or More [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	13,105	42
Past Due [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	15,557	206
Current Loans [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	25,533	8,669
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	2,862	2,638
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | 30 Days or More Past Due [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	113	114
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	52	50
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	518	42
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Past Due [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	683	206
Other Secured by 1-4 Family Residential Properties [Member] | Loans Secured by Real Estate [Member] | Current Loans [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	2,179	2,432
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	10,403	30
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member] | 30 Days or More Past Due [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	765	0
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	958	0
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	326	0
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member] | Past Due [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	2,049	0
Secured by 1-4 Family Residential Properties [Member] | Other Loans Secured by Real Estate [Member] | Current Loans [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	8,354	30
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	15,000
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | 30 Days or More Past Due [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due 90 Days or More [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Past Due [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	0
Other Real Estate Secured [Member] | Loans Secured by Real Estate [Member] | Current Loans [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	15,000
Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	12,825	6,207
Commercial and Industrial Loans [Member] | 30 Days or More Past Due [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	112	0
Commercial and Industrial Loans [Member] | Past Due 60 to 89 Days [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	452	0
Commercial and Industrial Loans [Member] | Past Due 90 Days or More [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	12,261	0
Commercial and Industrial Loans [Member] | Past Due [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	12,825	0
Commercial and Industrial Loans [Member] | Current Loans [Member]
Financing Receivable Modifications [Line Items]
Post-Modification Outstanding Recorded Investment	$ 0	$ 6,207