Investment Securities (Disclosure Regarding Length of Time on Investment Securities with Temporary Impairment) (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	$ 24,721	$ 31,350
Less than 12 months, gross unrealized losses	(175)	(189)
12 months or longer, fair value	6,815	18,768
12 months or longer, gross unrealized losses	(155)	(339)
Total, fair value	31,536	50,118
Total, gross unrealized losses	(330)	(528)
Agency Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	1,697	1,244
Less than 12 months, gross unrealized losses	(3)	(6)
12 months or longer, fair value	0	278
12 months or longer, gross unrealized losses	0	(2)
Total, fair value	1,697	1,522
Total, gross unrealized losses	(3)	(8)
State And Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	19,572	24,266
Less than 12 months, gross unrealized losses	(165)	(165)
12 months or longer, fair value	6,815	17,746
12 months or longer, gross unrealized losses	(155)	(330)
Total, fair value	26,387	42,012
Total, gross unrealized losses	(320)	(495)
Corporate Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, fair value	3,452	5,840
Less than 12 months, gross unrealized losses	(7)	(18)
12 months or longer, fair value	0	744
12 months or longer, gross unrealized losses	0	(7)
Total, fair value	3,452	6,584
Total, gross unrealized losses	$ (7)	$ (25)