Note 2 - Summary of Significant Accounting Policies - Restricted Cash and Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Total restricted cash and marketable securities	$ 30,499	$ 28,847	$ 21,940
Credit Card Processor Reserves [Member]
Total restricted cash and marketable securities	20,250	20,400
Federal Maritime Commission Escrow [Member]
Total restricted cash and marketable securities	8,958	6,882
Certificates of Deposit and Other Restricted Securities [Member]
Total restricted cash and marketable securities	$ 1,291	$ 1,565