Derivative Financial Instruments - Schedule of Amounts Related to Non-Hedging Interest Rate and Commodity Derivatives (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
States and political subdivisions [Member] | Designated as Hedging Instrument [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Interest income on tax-exempt securities (net ineffective portion of hedge)	$ (17)	$ 0	$ (7)	$ 0
Interest Rate Contract [Member] | Other Non-Interest Income [Member] | Non Designated as Hedging Instrument [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	997	784	3,841	1,906
Interest Rate Contract [Member] | Other Non-Interest Expense [Member] | Non Designated as Hedging Instrument [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	0	(1)	0	(2)
Commodity Contract [Member] | Non Designated as Hedging Instrument [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	864	351	2,474	3,054
Foreign Currency Derivative Contracts [Member] | Non Designated as Hedging Instrument [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	$ 38	$ 0	$ 42	$ 55