Note 9 - Business Segments (Details) - Summarized Financial Information Concerning Reportable Segments (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Net revenues from external customers	$ 142,436		$ 118,906
Operating income	42,571		7,684
Segment assets at period end *	2,134,347	[1]	2,133,925		2,159,433	2,087,523
* Including unconsolidated investments	7,510		2,789		7,076
Intersegment Eliminations [Member] | Product Segment [Member]
Segment Reporting Information [Line Items]
Intersegment revenues	20,594		6,581
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment revenues	20,594		6,581
Electricity Member | Including Unconsolidated Investments [Member]
Segment Reporting Information [Line Items]
Segment assets at period end *			2,046,817	[1]
Electricity Member
Segment Reporting Information [Line Items]
Net revenues from external customers	94,817		68,298
Operating income	30,918		(1,278)
Segment assets at period end *	2,003,991	[1]
* Including unconsolidated investments	7,510		2,789
Product Segment [Member] | Including Unconsolidated Investments [Member]
Segment Reporting Information [Line Items]
Segment assets at period end *			96,751	[1]
Product Segment [Member]
Segment Reporting Information [Line Items]
Net revenues from external customers	47,619		50,608
Operating income	11,653		8,962
Segment assets at period end *	130,356	[1]
Including Unconsolidated Investments [Member]
Segment Reporting Information [Line Items]
Segment assets at period end *			$ 2,143,568	[1]

[1] Including unconsolidated investments