Note 8 - Earnings Per Share (Details Textual) - shares
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Employee Stock Option [Member]        
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount 30,000 190,000 76,667 130,000