Note 4 - Fair Value Measurements - Quantitative Information for Fair Value Measurement of Level 3 (Details) $ in Millions	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Fair value	$ 17.6	$ 16.8
AZEDRA Commercialization [Member]
Fair value	$ 5.5	$ 5.5
AZEDRA Commercialization [Member] | Measurement Input, Default Rate [Member]
Measurement input	72	72
AZEDRA Commercialization [Member] | Measurement Input, Discount Rate [Member]
Measurement input	10	10
MIP - 1404 Commercialization [Member]
Fair value	$ 4.6	$ 4.5
MIP - 1404 Commercialization [Member] | Measurement Input, Default Rate [Member]
Measurement input	59	59
MIP - 1404 Commercialization [Member] | Measurement Input, Discount Rate [Member]
Measurement input	10	10
MIP-1095 Commercialization [Member]
Fair value	$ 0.4	$ 0.4
MIP-1095 Commercialization [Member] | Measurement Input, Default Rate [Member]
Measurement input	16	16
MIP-1095 Commercialization [Member] | Measurement Input, Discount Rate [Member]
Measurement input	10	10
Net sales targets [Member]
Fair value	$ 7.1	$ 6.4
Net sales targets [Member] | Measurement Input, Default Rate [Member] | Minimum [Member]
Measurement input	16	16
Net sales targets [Member] | Measurement Input, Default Rate [Member] | Maximum [Member]
Measurement input	72	72
Net sales targets [Member] | Measurement Input, Discount Rate [Member]
Measurement input	10	10