Allowance for Credit Losses (Summary of Loans Experiencing Financial Difficulties Subsequently Defaulted) (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($)
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	$ 40,729
Payments in Default
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	945
Commercial | Commercial, industrial and other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	37,474
Commercial | Commercial, industrial and other | Payments in Default
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	2
Commercial real estate | Non-construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	1,333
Commercial real estate | Non-construction | Payments in Default
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	828
Home equity | Commercial, industrial and other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	203
Home equity | Commercial, industrial and other | Payments in Default
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	104
Residential real estate | Commercial, industrial and other
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	1,708
Residential real estate | Commercial, industrial and other | Payments in Default
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	0
Premium finance receivables | Property and casualty insurance loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	11
Premium finance receivables | Property and casualty insurance loans | Payments in Default
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in payment default under restructured terms	$ 11