Note 23 - Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Quarterly Financial Information [Table Text Block]

	Three Months Ended
	Mar. 31, 2017			June 30, 2017			Sept. 30, 2017			Dec. 31, 2017			Mar. 31, 2018			June 30, 2018			Sept. 30, 2018			Dec. 31, 2018
	(Dollars in thousands, except per share amounts)
Revenues:
Electricity	$	115,776		$	110,896		$	110,876		$	128,045		$	132,489		$	122,179		$	116,891		$	138,320
Product		74,122			67,587			44,912			37,862			48,672			54,915			48,439			49,717
Other		--			881			1,397			458			2,862			1,205			1,150			2,428
Total revenues		189,898			179,364			157,185			166,365			184,023			178,299			166,480			190,465
Cost of revenues:
Electricity		66,036			63,196			64,444			73,164			73,482			81,236			79,845			63,692
Product		49,452			43,432			32,218			26,992			33,726			37,573			35,669			33,729
Other		--			2,243			1,330			1,853			3,443			2,028			2,174			2,235
Total cost of revenues		115,488			108,871			97,992			102,009			110,651			120,837			117,688			99,656
Gross profit		74,410			70,493			59,193			64,356			73,372			57,462			48,792			90,809
Operating expenses:
Research and development expenses		602			1,050			716			789			1,108			1,251			706			1,118
Selling and marketing expenses		4,363			4,090			3,630			3,517			3,699			3,712			8,578			3,813
General and administrative expenses		9,949			12,201			10,877			9,854			13,849			15,866			13,606			4,429
Impairment charge		--			--			--			--			--			--			--			13,464
Write-off of unsuccessful exploration activities		--			--			--			1,796			123			--			--			3
Operating income		59,496			53,152			43,970			48,400			54,593			36,633			25,902			67,982
Other income (expense):
Interest income		244			362			255			127			113			189			214			458
Interest expense, net		(14,923	)		(14,540	)		(11,692	)		(12,987	)		(14,344	)		(15,846	)		(18,700	)		(22,034	)
Derivatives and foreign currency transaction gains (losses)		1,338			1,703			(1,001	)		614			(1,599	)		(529	)		(383	)		(2,250	)
Income attributable to sale of tax benefits		6,157			4,356			3,506			3,859			7,361			3,556			4,066			4,020
Other non-operating income (expense), net		(92	)		6			(1,592	)		12			(20	)		7,373			309			117
Income from continuing operations, before income tax and equity in earnings (losses) of investees		52,220			45,039			33,446			40,025			46,104			31,376			11,408			48,293
Income tax benefit (provision)		(11,004	)		(32,765	)		(6,224	)		28,329			26,942			(29,105	)		(1,184	)		(31,386	)
Equity in earnings (losses) of investees, net		(1,599	)		(428	)		337			(267	)		1,210			388			(117	)		6,182
Income from continuing operations		39,617			11,846			27,559			68,087			74,256			2,659			10,107			23,089
Net loss (income) attributable to noncontrolling interest		(4,423	)		(3,206	)		(3,599	)		(3,467	)		(4,748	)		(3,002	)		474			(4,869	)
Net income (loss) attributable to the Company's stockholders	$	35,194		$	8,640		$	23,960		$	64,620		$	69,508		$	(343	)	$	10,581		$	18,220
Earnings (loss) per share attributable to the Company's stockholders
Basic:
Net income	$	0.71		$	0.17		$	0.48		$	1.28		$	1.37		$	(0.01	)	$	0.21		$	0.36
Diluted:
Net income	$	0.70		$	0.17		$	0.47		$	1.27		$	1.36		$	(0.01	)	$	0.21		$	0.36
Weighted average number of shares used in computation of earnings per share attributable to the Company's stockholders:
Basic		49,680			49,771			50,367			50,607			50,614			50,623			50,645			50,691
Diluted		50,491			50,624			50,867			51,053			51,051			50,958			50,963			50,936