Fair Value Measurements (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unused Commitments to Extend Credit	$ 11,671,663	$ 7,152,331
Mortgage Loans in Process of Foreclosure, Amount	10,100
Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Annual Amount	(200)
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount	1,000
Rabbi Trust [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	10,000	1,600
Alternative investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	82,700	14,100
Equity Securities, FV-NI	400	1,900
Equity Securities without Readily Determinable Fair Value, Amount	89,200	25,900
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	1,500
Fair Value, Nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other Assets, Fair Value Disclosure	2,300	2,800
Fair Value, Nonrecurring [Member] | Alternative investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unused Commitments to Extend Credit	42,800	25,800
Alternative investments, written up	$ 5,900	$ 5,800