Securities - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Fair value of pledged securities	$ 88,800,000		$ 94,300,000
Restricted stock investment in FHLB stock	4,100,000		4,100,000
Federal Reserve Bank stock	471,000		$ 471,000
Income tax provision applicable to realized gains	0	$ 12,000
Income tax benefit on realized losses	$ 0