Other Comprehensive Income (Loss) (Reclassification Adjustments Out of Accumulated Other Comprehensive Income) (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Unrealized gains/(losses) on investments available-for-sale Affected line item in the Statements of Income:
Investment securities gains		$ 36	$ 5	$ 115
Income before taxes		36	5	115
Tax expense		14	2	46
Net income		22	3	69
Amortization of defined benefit pension plan items Affected line item in the Statements of Income:
Recognized actuarial loss	[1]	1,736	(9,235)	9,340
Income before taxes		1,736	(9,235)	9,340
Tax expense		698	(3,662)	3,722
Net income		$ 1,038	$ (5,573)	$ 5,618

[1] This amount is included in the computation of net periodic benefit cost, see Note 13