Note 19 - Business Segments (Restated) (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Schedule of Segment Reporting Information, by Segment [Table Text Block]

	Electricity		Product		Consolidated
	(Dollars in thousands)
Year Ended December 31, 2017:
Net revenues from external customers	$	468,329	$	224,483	$	692,812
Intersegment revenues		—		109,040		109,040
Depreciation and amortization expense		111,676		3,470		115,146
Operating income		154,475		50,543		205,018
Segment assets at period end (*) ( 1 ) (As restated)		2,508,151		115,713		2,623,864
Expenditures for long-lived assets		252,581		6,653		259,234
* Including unconsolidated investments		—		34,084		34,084
Year Ended December 31, 2016:
Net revenues from external customers	$	436,292	$	226,299	$	662,591
Intersegment revenues		—		56,075		56,075
Depreciation and amortization expense		102,698		3,279		105,977
Operating income		126,828		75,054		201,882
Segment assets at period end ( 1 )		2,204,444		257,125		2,461,569
Expenditures for long-lived assets		147,211		4,719		151,930
Year Ended December 31, 2015 :
Net revenues from external customers	$	375,920	$	218,724	$	594,644
Intersegment revenues		—		48,559		48,559
Depreciation and amortization expense		103,892		3,314		107,206
Operating income		99,345		64,716		164,061
Segment assets at period end		2,044,346		229,636		2,273,982
Expenditures for long-lived assets		149,666		2,784		152,450

Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block]

	Year Ended December 31,
	2017			2016			2015
	(Dollars in thousands)
Revenues:
Total segment revenues	$	692,812		$	662,591		$	594,644
Intersegment revenues		109,040			56,075			48,559
Elimination of intersegment revenues		(109,040	)		(56,075	)		(48,559	)
Total consolidated revenues	$	692,812		$	662,591		$	594,644
Operating income:
Operating income	$	205,018		$	201,882		$	164,061
Interest income		988			971			297
Interest expense, net		(54,142	)		(67,389	)		(72,577	)
Foreign currency translation and transaction losses		2,654			(5,534	)		(1,622	)
Income attributable to sale of equity interest		17,878			16,503			25,431
Other non-operating income, net		(1,666	)		(5,345	)		(1,991	)
Total consolidated income before income taxes and equity in losses of investees	$	170,730		$	141,088		$	113,599

Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]

	Year Ended December 31,
	2017		2016		2015
	(Dollars in thousands)
Revenues from external customers attributable to: (1)
United States	$	301,132	$	307,025	$	286,509
Indonesia		28,968		100,856		93,191
Kenya		110,243		109,270		86,545
Turkey		125,166		46,270		57,356
Chile		8,895		58,032		34,478
Guatemala		27,991		30,086		27,897
New Zealand		33,395		—		—
Other foreign countries		57,022		11,052		8,668
Consolidated total	$	692,812	$	662,591	$	594,644

Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block]

	Year Ended December 31,
	2017		2016		2015
	(Dollars in thousands)
Long-lived assets (primarily power plants and related assets) located in:
United States	$	1,510,986	$	1,414,523	$	1,374,465
Kenya		340,970		327,157		375,257
Other foreign countries		281,333		199,559		107,407
Consolidated total	$	2,133,289	$	1,941,239	$	1,857,129

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

	Year Ended December 31,
	2017				2016				2015
	Revenues		%		Revenues		%		Revenues		%
	(Dollars in thousands)				(Dollars in thousands)				(Dollars in thousands)
Southern California Edison (1)	$	29,714		4.3	$	33,552		5.1	$	56,026		9.4
Southern California Public Power Authority  (1)		70,100		10.1		67,566		10.2		30,947		5.2
Sierra Pacific Power Company and Nevada Power Company (1)(2)		125,424		18.1		127,226		19.2		115,876		19.5
Hyundai ( 3 )		28,968		4.2		100,856		15.2		93,131		15.7
KPLC (1)		110,243		15.9		109,270		16.5		86,545		14.6