Note 4 - Fair Value Measurement and Fair Value of Financial Instruments - Contingent Consideration Obligations Inputs and Assumptions (Details)	Mar. 31, 2022	Sep. 30, 2021
Measurement Input, Revenue Discount Rate [Member]
Business combination, measurement input	0.044	0.035
Measurement Input, Discount Rate [Member]
Business combination, measurement input	0.098	0.110
Measurement Input, Revenue Volatility [Member]
Business combination, measurement input	0.083	0.105