Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Trade, allowance for credit losses	$ 90,000	$ 90,000
Property, plant and equipment, net	2,293,720,000	2,294,973,000
Construction-in-process	819,560,000	721,483,000
Operating leases right of use	19,753,000	19,357,000
Finance leases right of use	$ 5,762,000	$ 6,414,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	56,071,682	56,056,450
Common stock, shares outstanding (in shares)	56,071,682	56,056,450
Senior Secured Notes [Member]
Deferred financing costs	$ 10,712,000	$ 11,304,000
Senior Unsecured Bonds [Member]
Deferred financing costs	3,346,000	3,659,000
Variable Interest Entity, Primary Beneficiary [Member]
Property, plant and equipment, net	2,153,106,000	2,159,696,000
Construction-in-process	413,556	366,924
Operating leases right of use	7,675,000	7,825,000
Finance leases right of use	$ 159,000	$ 192,000