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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
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)	$ 979	$ 240	$ 1,414	$ 1,562
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	(5)	0	(3)
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)	13	38	145	66
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)	$ 8	$ 66	$ 14	$ 111