Securities - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014 Securities	Sep. 30, 2013	Sep. 30, 2014 Securities	Sep. 30, 2013	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]
Carrying value of pledged securities	$ 83,600,000		$ 83,600,000		$ 87,900,000
Restricted stock investment in FHLB stock	4,100,000		4,100,000		5,000,000
Federal Reserve Bank stock	471,000		471,000		471,000
Number of securities in unrealized loss position	43		43
Number of securities in continuous loss position	21		21
Income tax provision applicable to realized gains	0	51,000	45,000	54,000
Income tax benefit on realized losses	$ 0	$ 0	$ 0	$ 0