Investment Securities - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) Bond	Sep. 30, 2015	Sep. 30, 2016 USD ($) Bond	Sep. 30, 2015	Dec. 31, 2015 USD ($) Bond
Schedule of Available-for-sale Securities [Line Items]
Average yields (taxable equivalent) on securities	3.10%	2.43%	3.07%	2.45%
Market value of securities	$ 15,500		$ 15,500		$ 8,600
Securities sold under repurchase agreements	12,984		12,984		7,161	[1]
Company's investment in Federal Home Loan Bank stock	1,500		1,500		2,000
Company's investment in Federal Reserve Bank stock	$ 565		$ 565		$ 505
Municipal Securities
Schedule of Available-for-sale Securities [Line Items]
Bonds with unrealized loss positions | Bond	6		6		17
US Government Agencies
Schedule of Available-for-sale Securities [Line Items]
Bonds with unrealized loss positions | Bond	12		12		24
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Bonds with unrealized loss positions | Bond					1

[1] Derived from Audited December 31, 2015 Financial Statements