Loans and Leases - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2025	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unamortized premiums	$ 16,700	$ 16,700		$ (1,800)
Interest receivable	268,800	268,800		265,000
Loans and leases, net	52,949,913	$ 52,949,913		$ 51,815,602
Commercial real estate | Customer Concentration Risk | Loans and Finance Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration of credit risk		39.80%		40.70%
Asset-based | Payment Delay
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified loans	15,000	$ 15,000
Commercial non-mortgage | Customer Concentration Risk | Loans and Finance Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration of credit risk		34.90%		34.40%
Commercial non-mortgage | Payment Delay
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modified loans			$ 17,800
Collateral Pledged | Commercial portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	244,800	$ 244,800		$ 139,500
Collateral Pledged | Consumer portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	28,300	28,300		29,100
Collateral Pledged | Asset Pledged as Collateral | Federal Home Loan Bank Certificates and Obligations (FHLB)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net	17,600,000	17,600,000
Collateral Pledged | Asset Pledged as Collateral | Federal Reserve Bank Certificates And Obligations (FRB)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net	6,200,000	6,200,000
Collateral Value
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	$ 278,600	$ 278,600		$ 200,100