Note 10 - Fair Value of Financial Instruments - Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Cash and cash equivalents	$ 43,534	$ 43,425
Restricted cash	5,363	6,689
Note receivable	8,505	401
Total assets	57,402	50,515
Bank acceptance payable	6,481	15,860
Convertible senior notes	67,701	70,225
Total liabilities	74,182	86,085
Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents	43,534	43,425
Restricted cash	5,363	6,689
Note receivable	0	0
Total assets	48,897	50,114
Bank acceptance payable	0	0
Convertible senior notes	0	0
Total liabilities	0	0
Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents	0	0
Restricted cash	0	0
Note receivable	8,505	401
Total assets	8,505	401
Bank acceptance payable	6,481	15,860
Convertible senior notes	67,701	70,225
Total liabilities	74,182	86,085
Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents	0	0
Restricted cash	0	0
Note receivable	0	0
Total assets	0	0
Bank acceptance payable	0	0
Convertible senior notes	0	0
Total liabilities	$ 0	$ 0