Securities - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Securities pledged	$ 1,500,000	$ 1,500,000
Sale of securities	1,050,000	0
Residential mortgage backed securities
Schedule of Available-for-sale Securities [Line Items]
Estimated remaining term	4 years 8 months 12 days
U.S. Government and federal agency
Schedule of Available-for-sale Securities [Line Items]
Sale of securities	1,000,000
Gain on sale of securities	$ 50,000
Holding of securities greater than 10% of shareholders' equity	0	0