Note 9 - Financial Instruments - Effect of Derivative Instruments on Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Natural gas commodity contracts	$ 0	$ 414
Natural Gas Commodity Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Gain on derivative instruments, net	Gain on derivative instruments, net
Natural gas commodity contracts	$ 0	$ 235
Crude Oil Commodity Contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Gain on derivative instruments, net	Gain on derivative instruments, net
Natural gas commodity contracts	$ 0	$ 179