Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of collateral posted for the net assets/liability positions	$ 7,750,000		$ 7,750,000		$ 79,000
Not Designated as Hedging Instrument [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivatives recorded gains (losses) during the period	$ 42,000	$ 528,000	355,000	$ 2,200,000
Interest Rate Swaps/Derivatives [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Reclassification from accumulated other comprehensive income (loss) as increase to interest income			$ 561,000
Reclassification from accumulated other comprehensive income, time period			12 months