Note 5 - Earnings Per Share (Details) - Earnings Per Share - Basic and Diluted - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share, Basic and Diluted [Abstract]
Net income (in Dollars)	$ 6,373,489	$ 4,177,889
Basic earnings per common share (in Dollars per share)	$ 0.54	$ 0.52
Diluted earnings per common share (in Dollars per share)	$ 0.53	$ 0.52
Weighted average common shares outstanding	11,793,620	7,975,910
Weighted average common shares issuable upon exercise of stock options and under the employee stock purchase plan	160,329	121,534
Weighted average common and common equivalent shares outstanding	11,953,949	8,097,444