Note 5 - Fair Value Measurements - Fair Value Measurement Input (Details)	Sep. 30, 2020
Measurement Input, Probability of Achievement [Member]
Measurement Input	80
Measurement Input, Probability of Achievement [Member] | Minimum [Member]
Measurement Input	50
Measurement Input, Probability of Achievement [Member] | Maximum [Member]
Measurement Input	100
Measurement Input, Discount Rate [Member]
Measurement Input	8.7