Effect of Derivative and Hedging Activity, on Consolidated Statements of Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivatives designated as hedges
Derivative, Gain (Loss) on Derivative, Net	$ 116	$ 122	$ 162
Interest Rate Swaps Agreement | Designated as Hedging Instrument | Interest And Fee
Derivatives designated as hedges
Derivative, Gain (Loss) on Derivative, Net	$ 116	$ 122	$ 162