Note 3 - Cash, Cash Equivalents, Investments and Restricted Cash - Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash and cash equivalents	$ 334,944	$ 172,960
Restricted cash included in other long-term assets	127	116
Total cash, cash equivalents and restricted cash reported on the Consolidated Statements of Cash Flows	$ 335,071	$ 173,076	$ 172,818	$ 82,874