Note 3 - Stockholders' Equity (Details Textual) - Chief Executive Officer [Member] - Share-based Payment Arrangement, Option [Member] - $ / shares		6 Months Ended
	Mar. 06, 2019	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	25,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price	$ 5.20
Share-based Payment Arrangement, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		20.00%
Share-based Payment Arrangement, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		20.00%
Share-based Payment Arrangement, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		20.00%
Share-based Payment Arrangement, Tranche Four [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		20.00%
Share-based Payment Arrangement, Tranche Five [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		20.00%