Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Property, plant and equipment, net	$ 1,723,560	$ 1,734,691
Construction-in-process	$ 345,563	$ 293,542
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)	50,617,209	50,609,051
Common stock, shares outstanding (in shares)	50,617,209	50,609,051
Senior Secured Notes [Member]
Deferred financing costs	$ 7,693	$ 8,113
Other Loans, Limited and Non-recourse [Member]
Deferred financing costs	5,231	5,258
Senior Unsecured Bonds [Member]
Deferred financing costs	863	580
Other Loans, Full Recourse [Member]
Deferred financing costs	994	1,011
Variable Interest Entity, Primary Beneficiary [Member]
Property, plant and equipment, net	1,655,365	1,631,900
Construction-in-process	$ 149,872	$ 142,717