Borrowed Funds - Additional Information (Detail) - USD ($) $ in Millions		12 Months Ended
	Aug. 04, 2005	Dec. 31, 2015	Dec. 31, 2007	Dec. 31, 2006
Deposits [Line Items]
Trust preferred securities issued			$ 10.0	$ 12.5
Trust preferred securities, principal maturity date			Sep. 01, 2037
Trust preferred securities, principal maturity date				2036
Subordinated debt issued	$ 5.0
Subordinated debt at a fixed interest rate	6.35%
Maturity date of subordinated debt	Nov. 23, 2015
Minimum investment in the capital stock of the FHLB		0.20%
Specified value of certain transactions between the Bank and the FHLB		4.50%
Trust Preferred Securities [Member]
Deposits [Line Items]
Floating rate percentage			1.75%	1.66%
Floating rate description		3-month LIBOR