Note 9 - Cash, Cash Equivalents, Investments and Restricted Cash - Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Cash and cash equivalents	$ 131,094	$ 82,759
Restricted cash included in other long-term assets	115	115
Total cash, cash equivalents and restricted cash shown in the Condensed Consolidated Statements of Cash Flows	$ 131,209	$ 82,874	$ 104,539	$ 112,813