Subordinated Debentures - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified				1 Months Ended	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Dec. 30, 2008	Dec. 03, 2003 Private Placement [Member]	Sep. 30, 2012 Subordinated [Member]	Dec. 03, 2003 Subordinated [Member]
Subsidiary, Sale of Stock [Line Items]
Holding Company, closed a pooled private offering				5,000
Trust preferred securities with a liquidation amount				$ 1
Subordinated debentures						$ 5,155
Holding Company's investment in the common stock	155
Trust preferred securities and subordinated debentures have a variable rate of interest	2.85%	2.85%
Trust preferred securities and subordinated debentures have a stated percentage	3.31%	3.43%
Holding Company may redeem the subordinated debentures in a principal amount with integral multiples			$ 1
Percentage in which holding company redeem subordinated debentures			100.00%
Maturity date of subordinated debentures					Dec. 30, 2033
Cumulative deferred interest payments	$ 348	$ 210