Note 9 - Business Segments (Tables)

6 Months Ended

Jun. 30, 2017

Notes Tables

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

	Electricity		Product		Consolidated
	(Dollars in thousands)
Three Months Ended June 30, 2017:
Net revenue from external customers	$	111,777	$	67,587	$	179,364
Intersegment revenue		—		16,565		16,565
Operating income		36,117		17,035		53,152
Segment assets at period end (1)		2,323,618		187,015		2,510,633
Three Months Ended June 30, 2016:
Net revenue from external customers	$	104,001	$	55,860	$	159,861
Intersegment revenue		—		19,266		19,266
Operating income		32,814		19,073		51,887
Segment assets at period end		2,031,650		241,363		2,273,013
Six Months Ended June 30, 2017:
Net revenues from external customers	$	227,553	$	141,709	$	369,262
Intersegment revenues		—		32,778		32,778
Operating income		77,015		35,633		112,648
Segment assets at period end (1)		2,323,618		187,015		2,510,633
Six Months Ended June 30, 2016:
Net revenues from external customers	$	211,869	$	99,586	$	311,455
Intersegment revenues		—		21,206		21,206
Operating income		67,599		34,831		102,430
Segment assets at period end		2,031,650		241,363		2,273,013

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Revenue:
Total segment revenue	$	179,364		$	159,861		$	369,262		$	311,455
Intersegment revenue		16,565			19,266			32,778			21,206
Elimination of intersegment revenue		(16,565	)		(19,266	)		(32,778	)		(21,206	)
Total consolidated revenue	$	179,364		$	159,861		$	369,262		$	311,455
Operating income:
Operating income	$	53,152		$	51,887		$	112,648		$	102,430
Interest income		362			245			606			565
Interest expense, net		(14,540	)		(18,401	)		(29,463	)		(34,424	)
Derivatives and foreign currency transaction gains (losses)		1,703			(4,332	)		3,041			(2,370	)
Income attributable to sale of tax benefits		4,356			4,519			10,513			8,917
Other non-operating income (expense), net		6			49			(86	)		240
Total consolidated income before income taxes and equity in income of investees	$	45,039		$	33,967		$	97,259		$	75,358