Note 10 - Fair Value Measurement - Cash and Cash Equivalents (Details) - Fair Value, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Total assets	$ 24,284	$ 65,233	$ 43,594
Interest rate swap	507	3,514	6,535
Total liabilities	507	3,514	6,535
Commodity Contract [Member]
Commodity swap	3,047		1,106
Fair Value, Inputs, Level 1 [Member]
Total assets	21,237	65,233	42,488
Interest rate swap	0	0	0
Total liabilities	0	0	0
Fair Value, Inputs, Level 1 [Member] | Commodity Contract [Member]
Commodity swap	0		0
Fair Value, Inputs, Level 2 [Member]
Total assets	3,047	0	1,106
Interest rate swap	507	3,514	6,535
Total liabilities	507	3,514	6,535
Fair Value, Inputs, Level 2 [Member] | Commodity Contract [Member]
Commodity swap	3,047		1,106
Fair Value, Inputs, Level 3 [Member]
Total assets	0	0	0
Interest rate swap	0	0	0
Total liabilities	0	0	0
Fair Value, Inputs, Level 3 [Member] | Commodity Contract [Member]
Commodity swap	0		0
Money Market Funds [Member]
Cash equivalents	21,237	65,233	42,488
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Cash equivalents	21,237	65,233	42,488
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Cash equivalents	0	0	0
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Cash equivalents	$ 0	$ 0	$ 0