Note 9 - Property, Plant and Equipment and Construction-in-process - Activity in Construction and Development (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Balance	$ 721,483
Balance	893,198	$ 721,483
Projects Under Exploration and Development [Member]
Balance	50,702	51,528	$ 84,637
Cost incurred during the year	44,566	2,680	5,832
Transfer of projects under exploration and development to projects under construction		(3,506)	(38,941)
Balance	95,268	50,702	51,528
Projects Under Exploration and Development [Member] | Up-front Bonus Lease Costs [Member]
Balance	5,335	5,347	17,018
Cost incurred during the year	0	0	0
Transfer of projects under exploration and development to projects under construction		(12)	(11,671)
Balance	5,335	5,335	5,347
Projects Under Exploration and Development [Member] | Exploration and Development Costs [Member]
Balance	44,664	45,478	66,916
Cost incurred during the year	44,566	2,680	5,832
Transfer of projects under exploration and development to projects under construction		(3,494)	(27,270)
Balance	89,230	44,664	45,478
Projects Under Exploration and Development [Member] | Interest Capitalized [Member]
Balance	703	703	703
Cost incurred during the year	0	0	0
Transfer of projects under exploration and development to projects under construction		0	0
Balance	703	703	703
Construction in Progress [Member]
Balance	670,781	427,787	291,918
Cost incurred during the year	495,526	413,842	301,780
Transfer of projects under exploration and development to projects under construction		3,506	38,941
Balance	797,930	670,781	427,787
Transfer of completed projects to property, plant and equipment	(368,377)	(174,354)	(204,852)
Construction in Progress [Member] | Up-front Bonus Lease Costs [Member]
Balance	39,156	39,144	27,473
Cost incurred during the year	0	0	0
Transfer of projects under exploration and development to projects under construction		12	11,671
Balance	11,156	39,156	39,144
Transfer of completed projects to property, plant and equipment	(28,000)	0	0
Construction in Progress [Member] | Drilling And Construction Costs [Member]
Balance	611,553	379,117	258,484
Cost incurred during the year	489,953	403,296	298,215
Transfer of projects under exploration and development to projects under construction		3,494	27,270
Balance	761,129	611,553	379,117
Transfer of completed projects to property, plant and equipment	(340,377)	(174,354)	(204,852)
Construction in Progress [Member] | Interest Capitalized [Member]
Balance	20,072	9,526	5,961
Cost incurred during the year	5,573	10,546	3,565
Transfer of projects under exploration and development to projects under construction		0	0
Balance	25,645	20,072	9,526
Transfer of completed projects to property, plant and equipment	$ 0	$ 0	$ 0