Note 8 - Fair Value Measurements - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Contingent payments	$ 0	$ 0
Fair Value, Recurring [Member]
Cash and cash equivalents	250,195	344,557
Restricted cash	13,824	12,571
Investment available for sale	14,116	15,822
Contingent payments		62
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	250,195	344,557
Restricted cash	13,824	12,571
Investment available for sale	0	0
Contingent payments		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents	0	0
Restricted cash	0	0
Investment available for sale	0	0
Contingent payments		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents	0	0
Restricted cash	0	0
Investment available for sale	$ 14,116	15,822
Contingent payments		$ 62