Securities - Cash Proceeds from Sales Securities and Gross Realized Gains and Gross Realized Losses Included Earnings (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales of securities	$ 103,303	$ 112,149	$ 104,276
Gross realized gains on sales of securities:
Total gross realized gains on sales of securities	1,585	4,006	1,609
Gross realized losses on sales of securities
Total gross realized losses on sales of securities	(590)	(184)	(59)
U.S. government & agencies [Member]
Gross realized gains on sales of securities:
Total gross realized gains on sales of securities	0	0	165
Gross realized losses on sales of securities
Total gross realized losses on sales of securities	(100)	0	(5)
Obligations of states and political subdivisions [Member]
Gross realized gains on sales of securities:
Total gross realized gains on sales of securities	261	2,710	527
Gross realized losses on sales of securities
Total gross realized losses on sales of securities	(215)	0	(4)
Residential mortgage backed securities and collateralized mortgage obligations [Member]
Gross realized gains on sales of securities:
Total gross realized gains on sales of securities	250	594	713
Gross realized losses on sales of securities
Total gross realized losses on sales of securities	(199)	(158)	(32)
Corporate securities [Member]
Gross realized gains on sales of securities:
Total gross realized gains on sales of securities	1,022	464	204
Gross realized losses on sales of securities
Total gross realized losses on sales of securities	(29)	(16)	(12)
Commercial mortgage backed securities [Member]
Gross realized gains on sales of securities:
Total gross realized gains on sales of securities	0	43	0
Gross realized losses on sales of securities
Total gross realized losses on sales of securities	0	(10)	(6)
Other asset backed securities [Member]
Gross realized gains on sales of securities:
Total gross realized gains on sales of securities	52	195	0
Gross realized losses on sales of securities
Total gross realized losses on sales of securities	$ (47)	$ 0	$ 0