Derivative Financial Instruments - Summary of Fair Value of Derivative Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Total derivative assets	$ 14,993	$ 14,118
Total derivative liabilities	21,196	16,292
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Total derivative assets	4,871	3,351
Total derivative liabilities	1,656	5,351
Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Total derivative assets	4,871	3,351
Total derivative liabilities	1,656	5,351
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Total derivative assets	10,122	10,767
Total derivative liabilities	19,540	10,941
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Total derivative assets	8,524	10,012
Total derivative liabilities	19,148	10,933
Not Designated as Hedging Instrument [Member] | Mortgage Contracts [Member]
Derivative [Line Items]
Total derivative assets	1,537	747
Total derivative liabilities	352
Not Designated as Hedging Instrument [Member] | Foreign Currency Contracts [Member]
Derivative [Line Items]
Total derivative assets	61	8
Total derivative liabilities	$ 40	$ 8