Summary of Organization - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Organization [Line Items]
Date of entity incorporation				Jun. 23, 1995
Assets	$ 1,137,849			$ 1,137,849		$ 1,093,768
Loans, including Loans held for sale	740,900			740,900		706,634
Deposits	963,840			963,840		892,775
Stockholders' equity	101,622		$ 93,592	101,622	$ 93,592	$ 96,216	$ 85,108
Net income	2,227		1,533	6,441	4,573
Net income applicable to common Stockholders	$ 2,141		$ 1,448	$ 6,184	$ 4,296
Dividends on common stock, per share	$ 0.0375	$ 0.0375	$ 0.0375	$ 0.1125	$ 0.1125