Earnings Per Share (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Basic weighted average shares outstanding	4,861,411	4,843,911	4,856,584	4,841,829
Dilutive effect of granted options	5,628	10,364	8,493	7,683
Diluted weighted average shares outstanding	4,867,039	4,854,275	4,865,077	4,849,512
Net income	$ 1,629,042	$ 1,622,358	$ 5,043,806	$ 5,431,516
Net income per share-basic	$ 0.34	$ 0.33	$ 1.04	$ 1.12
Net income per share-diluted	$ 0.33	$ 0.33	$ 1.04	$ 1.12