Parent Company Only Condensed Financial Information - Condensed Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
ASSETS
Cash and cash equivalents	$ 65,147	$ 61,436	$ 63,816	$ 34,275
Other assets	1,680	2,202
Total assets	222,131	250,920
Liabilities and Equity
Subordinated debentures	5,155	5,155
Stockholders' equity	24,362	9,944	11,431	15,989
Total liabilities and stockholder's equity	222,131	250,920
Parent Company [Member]
ASSETS
Cash and cash equivalents	5,193	560	449	745
Investment in banking subsidiary	23,552	13,827
Investment in and advances to other subsidiaries	1,222	1,212
Other assets	8	264
Total assets	29,975	15,863
Liabilities and Equity
Subordinated debentures	5,155	5,155
Accrued expenses and other liabilities	458	764
Stockholders' equity	24,362	9,944
Total liabilities and stockholder's equity	$ 29,975	$ 15,863