Note 10 - Cash, Cash Equivalents, Investments and Restricted Cash - Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Cash and cash equivalents	$ 197,012	$ 172,704
Restricted cash included in other long-term assets	115	114
Total cash, cash equivalents and restricted cash reported on the Condensed Consolidated Statements of Cash Flows	$ 197,127	$ 172,818	$ 83,188	$ 82,874