Note 4 - Fair Value Measurements - Assets and Liabilities Measured On Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Derivatives	$ 13,591	$ 0
Derivatives	4,075	0
Fair Value, Recurring [Member]
Total recurring fair value measurements		$ 0
Commodity Contract [Member]
Total liabilities	15,467
Commodity Contract [Member] | Fair Value, Recurring [Member]
Derivative assets	2,199
Derivatives	13,591
Derivatives	4,075
Total liabilities	17,666
Total recurring fair value measurements	(15,467)
Commodity Contract [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Derivative assets	0
Derivatives	0
Derivatives	0
Total liabilities	0
Total recurring fair value measurements	0
Commodity Contract [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative assets	2,199
Derivatives	13,591
Derivatives	4,075
Total liabilities	17,666
Total recurring fair value measurements	(15,467)
Commodity Contract [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Derivative assets	0
Derivatives	0
Derivatives	0
Total liabilities	0
Total recurring fair value measurements	$ 0