Note 1 - Basis of Presentation - Summary of Reconciliation of Cash, Cash Equivalents, and Restricted Cash in the Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash, cash equivalents and $1,512 and $5,835 in restricted cash at beginning of period	$ 437,648	$ 268,108
Cash and cash equivalents	464,049	388,024
Restricted cash	1,512	1,512
Cash, cash equivalents and $1,512 in restricted cash at end of each period	465,561	389,536
Net increase in cash, cash equivalents and restricted cash	$ 27,913	$ 121,428