Note 6 - Supplemental Balance Sheet and Cash Flow Information - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Accrued costs of construction, including capitalized interest	$ 9,197	$ 12,702
Accrued costs of long-lived assets	21	0
Accrued equity issuance costs	0	1,684
Debt issuance costs and premium amortized to cost of construction	106	153
Right-of-use assets obtained in exchange for operating lease liabilities	1,368	2,838
Net decrease in right-of-use assets and operating lease liabilities due to lease remeasurement	(206)	(12,189)
Interest paid	3,552	2,063
Cash, beginning of year	2,174	6,805
Restricted cash, beginning of year	39,222	197,130
Cash and restricted cash, beginning of year	41,396	203,935
Cash, end of period	2,556	3,796
Restricted cash, end of period	16,633	38,392
Cash and restricted cash, end of period	$ 19,189	$ 42,188