Investment Securities (Disclosure Regarding Length of Time on Investment Securities with Temporary Impairment) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, Fair Value	$ 42,758	$ 38,302
Less than 12 months, Gross unrealized losses	(471)	(269)
12 months or longer, Fair value	18,895	47,079
12 months or longer, Gross unrealized losses	(472)	(769)
Total, Fair value	61,653	85,381
Total, Gross unrealized losses	(943)	(1,038)
Agency Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, Fair Value	299	3,735
Less than 12 months, Gross unrealized losses	(1)	(20)
12 months or longer, Fair value	1,972	0
12 months or longer, Gross unrealized losses	(8)	0
Total, Fair value	2,271	3,735
Total, Gross unrealized losses	(9)	(20)
State and Municipal Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, Fair Value	42,209	27,679
Less than 12 months, Gross unrealized losses	(470)	(217)
12 months or longer, Fair value	16,422	47,079
12 months or longer, Gross unrealized losses	(463)	(769)
Total, Fair value	58,631	74,758
Total, Gross unrealized losses	(933)	(986)
Corporate Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less than 12 months, Fair Value	250	6,888
Less than 12 months, Gross unrealized losses	0	(32)
12 months or longer, Fair value	501	0
12 months or longer, Gross unrealized losses	(1)	0
Total, Fair value	751	6,888
Total, Gross unrealized losses	$ (1)	$ (32)