Loans and Allowance for Credit Losses - Summary of Aging Analysis of Modifications (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Mar. 31, 2025
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	$ 38,531	$ 23,328
Current | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	23,455	18,280
30-59 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	11,701	1,230
60-89 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	0	40
90+ Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	3,375	3,778
Commercial loans | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months		616
Commercial loans | Commercial real estate | Current | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months		616
Commercial loans | Commercial real estate | 30-59 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months		0
Commercial loans | Commercial real estate | 60-89 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months		0
Commercial loans | Commercial real estate | 90+ Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months		0
Commercial loans | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	38,052	20,314
Commercial loans | Commercial and industrial | Current | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	22,976	16,536
Commercial loans | Commercial and industrial | 30-59 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	11,701	0
Commercial loans | Commercial and industrial | 60-89 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	0	0
Commercial loans | Commercial and industrial | 90+ Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	3,375	3,778
Commercial loans | Commercial construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months		1,006
Commercial loans | Commercial construction | Current | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months		0
Commercial loans | Commercial construction | 30-59 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months		1,006
Commercial loans | Commercial construction | 60-89 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months		0
Commercial loans | Commercial construction | 90+ Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months		0
Business banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	25
Business banking | Current | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	25
Business banking | 30-59 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	0
Business banking | 60-89 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	0
Business banking | 90+ Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	0
Consumer loans | Consumer real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	454	1,392
Consumer loans | Consumer real estate | Current | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	454	1,128
Consumer loans | Consumer real estate | 30-59 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	0	224
Consumer loans | Consumer real estate | 60-89 Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	0	40
Consumer loans | Consumer real estate | 90+ Days Past Due | Accrual
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable, modified, after 12 months	$ 0	$ 0