Note 8 - Fair Value Measurement - Cash and Cash Equivalents (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Total assets	$ 71,995	$ 100,531
Interest rate swap	7,606	4,603
Total liabilities	7,606	4,603
Fair Value, Inputs, Level 1 [Member]
Total assets	71,995	100,531
Interest rate swap	0	0
Total liabilities	0	0
Fair Value, Inputs, Level 2 [Member]
Total assets	0	0
Interest rate swap	7,606	4,603
Total liabilities	7,606	4,603
Fair Value, Inputs, Level 3 [Member]
Total assets	0	0
Interest rate swap	0	0
Total liabilities	0	0
Money Market Funds [Member]
Cash equivalents	70,483	94,696
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Cash equivalents	70,483	94,696
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Cash equivalents	0	0
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Cash equivalents	0	0
Restricted Cash [Member]
Other noncurrent assets	1,512	5,835
Restricted Cash [Member] | Fair Value, Inputs, Level 1 [Member]
Other noncurrent assets	1,512	5,835
Restricted Cash [Member] | Fair Value, Inputs, Level 2 [Member]
Other noncurrent assets	0	0
Restricted Cash [Member] | Fair Value, Inputs, Level 3 [Member]
Other noncurrent assets	$ 0	$ 0