Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Trade, allowance for credit losses	$ 779,000	$ 0
Property, plant and equipment, net	2,038,038,000	1,971,415,000
Construction-in-process	394,123,000	376,555,000
Operating leases right of use	17,638,000	17,405,000
Finance leases right of use	$ 13,280,000	$ 14,161,000
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)	51,067,163	51,031,652
Common stock, shares outstanding (in shares)	51,067,163	51,031,652
Senior Secured Notes [Member]
Deferred financing costs	$ 5,802,000	$ 6,317,000
Other Loans, Limited and Non-recourse [Member]
Deferred financing costs	9,514,000	10,482,000
Senior Unsecured Bonds [Member]
Deferred financing costs	929,000	675,000
Other Loans, Full Recourse [Member]
Deferred financing costs	1,430,000	1,519,000
Variable Interest Entity, Primary Beneficiary [Member]
Property, plant and equipment, net	1,931,033	1,880,547
Construction-in-process	182,813	149,830
Operating leases right of use	5,527,000	4,688,000
Finance leases right of use	$ 8,117,000	$ 8,479,000