Securities - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($) Bond	Sep. 30, 2014	Sep. 30, 2015 USD ($) Bond	Sep. 30, 2014	Dec. 31, 2014 USD ($) Bond
Schedule of Available-for-sale Securities [Line Items]
Average yields (taxable equivalent) on securities	2.40%	2.43%	2.40%	2.39%
Market value of securities	$ 12,400		$ 12,400		$ 8,500
Securities sold under repurchase agreements	10,491		10,491		6,012	[1]
Company's investment in Federal Home Loan Bank stock	1,600		1,600		1,900
Company's investment in Federal Reserve Bank stock	$ 460		$ 460		$ 382
Municipal Securities
Schedule of Available-for-sale Securities [Line Items]
Bonds with unrealized loss positions | Bond	27		27		29
US Government Agencies
Schedule of Available-for-sale Securities [Line Items]
Bonds with unrealized loss positions | Bond	9		9		13
Certificates of Deposit
Schedule of Available-for-sale Securities [Line Items]
Bonds with unrealized loss positions | Bond					3

[1] Derived from the audited consolidated financial statements.