Note 2 - Significant Accounting Policies and Recent Accounting Pronouncements (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Table Text Block]

	For the years ended December 31,
	2019		2020		2021
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	$	148,928	$	143,922	$	276,002
Restricted cash – current portion		6,912		4,998		8,856
Restricted cash – non-current portion		40,031		42,976		68,670
Total cash, cash equivalents and restricted cash	$	195,871	$	191,896	$	353,528

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

	2019	2020	2021
A	22%	21%	16%
B	24%	20%	20%
C	10%	11%	12%
D	38%	29%	12%
E	3%	10%	9%
Total	97%	91%	69%