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	3 Months Ended
	Mar. 31, 2021	Mar. 31, 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	452,928	242,604
Restricted cash	1,512	4,881
Cash, cash equivalents and $1,512 and $4,881 in restricted cash at end of period	454,440	247,485
Net increase (decrease) in cash, cash equivalents and restricted cash	$ 16,792	$ (20,623)