Loans (Modification to Borrowers Experiencing Financial Difficulty) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 21,891,812	$ 20,754,813
Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 3,858	$ 8,138
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.00%	0.00%
Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0	$ 45,835
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.00%	0.20%
Contractual Interest Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0	$ 31,302
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.00%	0.20%
Commercial Portfolio Segment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 6,306,980	$ 6,109,532
Commercial Portfolio Segment [Member] | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 2,186	$ 6,126
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.00%	0.10%
Commercial Portfolio Segment [Member] | Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0	$ 45,835
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.00%	0.80%
Commercial Portfolio Segment [Member] | Contractual Interest Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0	$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.00%	0.00%
Construction | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 1,672	$ 2,012
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.10%	0.10%
Construction | Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0	$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.00%	0.00%
Construction | Contractual Interest Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0	$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.00%	0.00%
Commercial Real Estate Owner Occupied
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 3,987,913	$ 3,622,201
Commercial Real Estate Owner Occupied | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts		$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage		0.00%
Commercial Real Estate Owner Occupied | Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts		$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage		0.00%
Commercial Real Estate Owner Occupied | Contractual Interest Rate Reduction
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts		$ 31,302
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage		0.90%