Note 9 - Property, Plant and Equipment and Construction-in-process - Activity in Construction and Development (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Balance	$ 479,315
Balance	721,483	$ 479,315
Insurance recoveries	0	(4,700)	$ (35,435)
Projects Under Exploration and Development [Member]
Balance	51,528	84,637	70,958
Cost incurred during the year	2,680	5,832	17,215
Transfer of projects under exploration and development to projects under construction	(3,506)	(38,941)	(3,536)
Balance	50,702	51,528	84,637
Projects Under Exploration and Development [Member] | Up-front Bonus Lease Costs [Member]
Balance	5,347	17,018	17,018
Cost incurred during the year	0	0	0
Transfer of projects under exploration and development to projects under construction	(12)	(11,671)	0
Balance	5,335	5,347	17,018
Projects Under Exploration and Development [Member] | Exploration and Development Costs [Member]
Balance	45,478	66,916	53,237
Cost incurred during the year	2,680	5,832	17,215
Transfer of projects under exploration and development to projects under construction	(3,494)	(27,270)	(3,536)
Balance	44,664	45,478	66,916
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	0
Balance	703	703	703
Construction in Progress [Member]
Balance	427,787	291,918	190,732
Cost incurred during the year	413,842	301,780	267,237
Transfer of projects under exploration and development to projects under construction	3,506	38,941	3,536
Balance	670,781	427,787	291,918
Insurance recoveries			(35,435)
Transfer of completed projects to property, plant and equipment	(174,354)	(204,852)	(134,152)
Construction in Progress [Member] | Up-front Bonus Lease Costs [Member]
Balance	39,144	27,473	27,473
Cost incurred during the year	0	0	0
Transfer of projects under exploration and development to projects under construction	12	11,671	0
Balance	39,156	39,144	27,473
Insurance recoveries			0
Transfer of completed projects to property, plant and equipment	0	0	0
Construction in Progress [Member] | Drilling And Construction Costs [Member]
Balance	379,117	258,484	160,398
Cost incurred during the year	403,296	298,215	264,137
Transfer of projects under exploration and development to projects under construction	3,494	27,270	3,536
Balance	611,553	379,117	258,484
Insurance recoveries			(35,435)
Transfer of completed projects to property, plant and equipment	(174,354)	(204,852)	(134,152)
Construction in Progress [Member] | Interest Capitalized [Member]
Balance	9,526	5,961	2,861
Cost incurred during the year	10,546	3,565	3,100
Transfer of projects under exploration and development to projects under construction	0	0	0
Balance	20,072	9,526	5,961
Insurance recoveries			0
Transfer of completed projects to property, plant and equipment	$ 0	$ 0	$ 0