Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Trade, allowance for credit losses	$ 253,000	$ 597,000
Property, plant and equipment, net	2,298,903,000	2,099,046,000
Construction-in-process	615,482,000	479,315,000
Operating leases right of use	19,690,000	16,347,000
Finance leases right of use	$ 7,002,000	$ 11,633,000
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)	56,001,501	55,983,259
Common stock, shares outstanding (in shares)	56,001,501	55,983,259
Senior Secured Notes [Member]
Deferred financing costs	$ 4,640,000	$ 5,318,000
Other Loans, Limited and Non-recourse [Member]
Deferred financing costs	7,313,000	8,557,000
Senior Unsecured Bonds [Member]
Deferred financing costs	3,659,000	3,426,000
Variable Interest Entity, Primary Beneficiary [Member]
Property, plant and equipment, net	2,167,620	1,978,220
Construction-in-process	301,687,000	198,812,000
Operating leases right of use	7,973,000	4,712,000
Finance leases right of use	$ 224,000	$ 7,001,000