Note 4 - Fair Value Measurements - Quantitative Information for Fair Value Measurement of Level 3 (Details) $ in Millions	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair value	$ 3.6	$ 3.9
MIP-1095 Commercialization [Member]
Fair value	$ 0.4	$ 0.5
MIP-1095 Commercialization [Member] | Measurement Input, Probability of Success [Member]
Measurement input	0.18	0.18
MIP-1095 Commercialization [Member] | Measurement Input, Period of Expected Milestone Achievement [Member]
Measurement input	2,027	2,026
MIP-1095 Commercialization [Member] | Measurement Input, Discount Rate [Member]
Measurement input	0.1	0.1
The 1404 Commercialization [Member]
Fair value	$ 0.2	$ 0.3
The 1404 Commercialization [Member] | Measurement Input, Probability of Success [Member]
Measurement input	0.43	0.43
The 1404 Commercialization [Member] | Measurement Input, Period of Expected Milestone Achievement [Member] | Minimum [Member]
Measurement input	2,023	2,022
The 1404 Commercialization [Member] | Measurement Input, Period of Expected Milestone Achievement [Member] | Maximum [Member]
Measurement input	2,035	2,035
The 1404 Commercialization [Member] | Measurement Input, Discount Rate [Member]
Measurement input	0.1	0.1
Net sales targets [Member]
Fair value	$ 3.0	$ 3.1
Net sales targets [Member] | Measurement Input, Probability of Success [Member] | Minimum [Member]
Measurement input	0.18	0.18
Net sales targets [Member] | Measurement Input, Probability of Success [Member] | Maximum [Member]
Measurement input	0.9	0.9
Net sales targets [Member] | Measurement Input, Discount Rate [Member]
Measurement input	0.1	0.1