Note 2 - Summary of Significant Accounting Policies - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Prepaid tour expenses	$ 15,630	$ 10,617
Prepaid air expense	4,415	2,973
Prepaid marketing, commissions and other expenses	4,026	2,622
Prepaid client insurance	3,064	2,436
Prepaid corporate insurance	1,376	1,158
Prepaid port agent fees	491	1,433
Prepaid income taxes	53	24
Total prepaid expenses	$ 29,055	$ 21,263