Note 1 - General and Basis of Presentation (Details) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended					3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended								0 Months Ended	3 Months Ended
	Jun. 20, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Selling and Marketing Expense [Member] Southern California Edison Company [Member]	Jun. 30, 2014 Reclassification out of Accumulated Other Comprehensive Income [Member]	Jun. 30, 2013 Reclassification out of Accumulated Other Comprehensive Income [Member]	Jun. 30, 2014 Reclassification out of Accumulated Other Comprehensive Income [Member]	Jun. 30, 2013 Reclassification out of Accumulated Other Comprehensive Income [Member]	Jun. 30, 2014 Southern California Edison Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 Southern California Edison Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 Southern California Edison Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 Southern California Edison Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Mar. 31, 2013 Southern California Edison Company [Member]	Jun. 30, 2014 Primary Customers [Member] Accounts Receivable [Member] Customer Concentration Risk [Member]	Dec. 31, 2013 Primary Customers [Member] Accounts Receivable [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 Sierra Pacific Power Company And Nevada Power Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 Sierra Pacific Power Company And Nevada Power Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 Sierra Pacific Power Company And Nevada Power Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 Sierra Pacific Power Company And Nevada Power Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 Hawaii Electric Light Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 Hawaii Electric Light Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 Hawaii Electric Light Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 Hawaii Electric Light Company [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 Kenya Power And Lighting Co Limited [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 Kenya Power And Lighting Co Limited [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 Kenya Power And Lighting Co Limited [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 Kenya Power And Lighting Co Limited [Member] Sales Revenue, Net [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 UNITED STATES	Dec. 31, 2013 UNITED STATES	Jun. 30, 2014 Foreign Countries [Member]	Dec. 31, 2013 Foreign Countries [Member]	Jun. 30, 2014 Maximum [Member]	Dec. 31, 2013 Maximum [Member]	Mar. 26, 2014 Heber Solar Project [Member]	Jun. 30, 2014 Heber Solar Project [Member]	Mar. 31, 2013 Heber Solar Project [Member]
Note 1 - General and Basis of Presentation (Details) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		$ 36,000	$ 42,000	$ 72,000	$ 84,000
Interest Expense		22,072,000	17,504,000	42,590,000	33,367,000				58,000	68,000	116,000	136,000
Income Tax Expense (Benefit)		4,967,000	5,780,000	11,287,000	9,827,000				22,000	26,000	44,000	52,000
Termination Fees								9,000,000
Contract Extension Period																	6 years
Sales Price of Disposition																																						35,250,000
Proceeds from Sales of Business, Affiliate and Productive Assets																																							20,250,000	15,000,000
Gain (Loss) on Sale of Project																																							7,600,000
Exploration Abandonment and Impairment Expense		8,107,000		8,107,000
Loan Principal Prepayment	4,275,000
Cash, Cash Equivalents, and Short-term Investments		80,120,000	28,893,000	80,120,000	28,893,000	57,354,000	66,628,000																									21,790,000	13,805,000	69,129,000	56,133,000
Cash, FDIC Insured Amount																																				250,000	250,000
Accounts Receivable, Net, Current		78,764,000		78,764,000		95,365,000																												48,814,000	32,231,000
Concentration Risk, Percentage													13.50%	12.40%	12.70%	12.10%		51.80%	35.00%	17.40%	14.90%	17.60%	17.80%	10.10%	8.60%	9.60%	8.90%	16.90%	10.30%	15.60%	9.50%
Provision for Doubtful Accounts				$ 0