Derivative Financial Instruments - Schedule of Amounts Related to Non-Hedging Interest Rate and Commodity Derivatives (Detail) - Non Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest Rate Contract [Member] | Other Non-Interest Income [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	$ 215	$ 699	$ 1,188	$ 2,889
Interest Rate Contract [Member] | Other Non-Interest Expense [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	0	2	0	(2)
Commodity Contract [Member] | Other Non-Interest Income [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	109	456	322	492
Foreign Currency Derivative Contracts [Member] | Other Non-Interest Income [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	$ 12	$ 53	$ 41	$ 203