Note 9 - Business Segments (Tables)

3 Months Ended

Mar. 31, 2017

Notes Tables

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

	Electricity		Product		Consolidated
	(Dollars in thousands)
Three Months Ended March 31, 2017:
Net revenues from external customers	$	115,776	$	74,122	$	189,898
Intersegment revenues		—		16,213		16,213
Operating income		40,898		18,598		59,496
Segment assets at period end		2,282,837		217,051		2,499,888
Three Months Ended March 31, 2016:
Net revenues from external customers	$	107,868	$	43,726	$	151,594
Intersegment revenues		—		1,941		1,941
Operating income		34,785		15,758		50,543
Segment assets at period end		2,048,471		211,663		2,260,134

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

	Three Months Ended March 31,
	2017			2016
Revenue:
Total segment revenue	$	189,898		$	151,594
Intersegment revenue		16,213			1,941
Elimination of intersegment revenue		(16,213	)		(1,941	)
Total consolidated revenue	$	189,898		$	151,594
Operating income:
Operating income	$	59,496		$	50,543
Interest income		244			320
Interest expense, net		(14,923	)		(16,023	)
Derivatives and foreign currency transaction gains (losses)		1,338			1,962
Income attributable to sale of tax benefits		6,157			4,398
Other non-operating income (expense), net		(92	)		191
Total consolidated income before income taxes and equity in income of investees	$	52,220		$	41,391