Earnings Per Share - Basic and diluted earnings per share (Details) (USD $)	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Numerator for earnings per share - net income	$ 5,700,493	$ 5,407,456
Denominator:
Denominator for basic earnings per share - weighted average shares	12,065,012	11,940,200
Effect of dilutive securities:
Stock options and other share awards	222,480	238,640
Denominator for diluted earnings per share	12,287,492	12,178,840
Earnings per share:
Basic (in dollars per share)	$ 0.47	$ 0.45
Diluted (in dollars per share)	$ 0.46	$ 0.44