Condensed Financial Information of Parent Company - Condensed Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Cash and due from non-affiliated banks	$ 6,181	$ 6,789
Premises and equipment, net	11,882	10,620
Other assets	2,504	2,901
Total assets	390,486	331,135
LIABILITIES
Other liabilities	2,651	1,534
Total liabilities	351,248	293,999
Total shareholders' equity	39,238	37,136	36,585
Total liabilities and shareholders' equity	390,486	331,135
Parent Company
ASSETS
Cash and due from non-affiliated banks	2,445	3,884	9,053
Investments in subsidiaries	35,625	32,456
Premises and equipment, net		1
Other assets	1,732	1,266
Total assets	39,802	37,607
LIABILITIES
Deferred directors' compensation	414	337
Other liabilities	150	134
Total liabilities	564	471
Total shareholders' equity	39,238	37,136
Total liabilities and shareholders' equity	$ 39,802	$ 37,607