Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, plant and equipment, net	$ 1,840,558	$ 1,734,691
Construction-in-process	$ 316,447	$ 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)	50,630,138	50,609,051
Common stock, shares outstanding (in shares)	50,630,138	50,609,051
Senior Secured Notes [Member]
Deferred financing costs	$ 7,987	$ 8,113
Other Loans, Limited and Non-recourse [Member]
Deferred financing costs	5,025	5,258
Senior Unsecured Bonds [Member]
Deferred financing costs	813	580
Other Loans, Full Recourse [Member]
Deferred financing costs	970	1,011
Variable Interest Entity, Primary Beneficiary [Member]
Property, plant and equipment, net	1,759,608	1,631,900
Construction-in-process	$ 100,184	$ 142,717