Note 5 - Earnings Per Share (Details Textual) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Dilutive Securities Included in Computation of Earnings Per Share Amount Stock Option (in shares)	878,408	1,052,410
Dilutive Securities Included in Computation of Earnings Per Share Amount Restricted Stock (in shares)	25,833	11,666
Incremental Common Shares Attributable to Share-based Payment Arrangements, Total (in shares)	211,286	484,843
Share-based Payment Arrangement, Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares)	653,500	448,250