Note 4 - Fair Value Measurements - Contingent Consideration Liabilities (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Molecular Insight Pharmaceuticals, Inc. [Member] | Milestone Payment upon First Commercial Sale [Member]
Contingent Consideration	$ 14,984
Molecular Insight Pharmaceuticals, Inc. [Member] | Milestone Payment upon Achievement of All Levels of Net Sales [Member]
Contingent Consideration	70,000
Molecular Insight Pharmaceuticals, Inc. [Member] | Milestone Payment upon Achievement of Net Sales Level 2 [Member]
Contingent Consideration	5,000
Molecular Insight Pharmaceuticals, Inc. [Member] | Milestone Payment upon Achievement of Net Sales Level 3 [Member]
Contingent Consideration	10,000
Molecular Insight Pharmaceuticals, Inc. [Member] | Milestone Payment upon Achievement of Net Sales Level 4 [Member]
Contingent Consideration	20,000
Molecular Insight Pharmaceuticals, Inc. [Member] | Milestone Payment upon Achievement of Net Sales Level 5 [Member]
Contingent Consideration	30,000
Milestone Payment upon Achievement of Net Sales Level 1 [Member] | Milestone Payment upon Achievement of All Levels of Net Sales [Member]
Contingent Consideration	5,000
The 1095 Program[Member] | Molecular Insight Pharmaceuticals, Inc. [Member] | Milestone Payment upon First Commercial Sale [Member]
Contingent Consideration	5,000
The 1404 Program [Member] | Molecular Insight Pharmaceuticals, Inc. [Member] | Milestone Payment upon First Commercial Sale [Member]
Contingent Consideration	$ 9,984