Loans and Leases - Performance of Loans that have been Modified in the Last 12 Months (Details) $ in Millions	Sep. 30, 2025 USD ($)
Financing Receivable, Troubled Debt Restructuring [Line Items]
Non-Accruing	$ 141
Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	347
30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	9
90+ Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	0
Commercial: | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Non-Accruing	18
Commercial: | Commercial and industrial | Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	140
Commercial: | Commercial and industrial | 30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	9
Commercial: | Commercial and industrial | 90+ Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	0
Commercial: | Commercial real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Non-Accruing	121
Commercial: | Commercial real estate | Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	206
Commercial: | Commercial real estate | 30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	0
Commercial: | Commercial real estate | 90+ Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	0
Consumer: | Consumer Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Non-Accruing	2
Consumer: | Consumer Real Estate | Current
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	1
Consumer: | Consumer Real Estate | 30-89 Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	0
Consumer: | Consumer Real Estate | 90+ Days Past Due
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans	$ 0