Note 9 - Cash, Cash Equivalents, Investments and Restricted Cash - Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Cash and cash equivalents	$ 226,091	$ 334,944
Restricted cash included in other long-term assets	120	127
Total cash, cash equivalents and restricted cash reported on the Condensed Consolidated Statements of Cash Flows	$ 226,211	$ 335,071	$ 179,588	$ 173,076