Other Comprehensive Income (Loss) (Reclassification Adjustments Out of Accumulated Other Comprehensive Income) (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Unrealized gains/(losses) on investments available-for-sale Affected line item in the Statements of Income:
Investment securities gains	$ 0		$ 0
Income before taxes	0		0
Tax expense	0		0
Net income	0		0
Amortization of defined benefit pension plan items Affected line item in the Statements of Income:
Recognition of unrealized gain (loss)	292,000	[1]	48,000	[1]
Income before taxes	292,000		48,000
Tax expense	116,000		37,000
Net income	$ 176,000		$ 11,000

[1] This amount is included in the computation of net periodic benefit cost, see Note 9.