Note 1 - General and Basis of Presentation (Details) (USD $)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Note 1 - General and Basis of Presentation (Details) [Line Items]
Valuation Allowances and Reserves, Adjustments		$ 3,100,000				$ 32,700,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	42,000		47,000	84,000	93,000
Interest Expense	17,504,000		14,263,000	33,367,000	29,141,000
Income Tax Expense (Benefit)	5,780,000	(4,269,000)	3,884,000	9,827,000	9,060,000	(3,091,000)
Cash, Cash Equivalents, and Short-term Investments	28,893,000		66,684,000	28,893,000	66,684,000	66,628,000	99,886,000
Accounts Receivable, Net, Current	67,545,000			67,545,000		55,680,000
Percentage of Total Accounts Receivables	56.70%			56.70%		45.00%
Southern California Edison Company [Member]
Note 1 - General and Basis of Presentation (Details) [Line Items]
Termination Fees	9,000,000			9,000,000
Contract Extension Period				6 years
Percentage Of Total Revenue	12.40%		17.00%	12.10%	18.60%
Sierra Pacific Power Company And Nevada Power Company [Member]
Note 1 - General and Basis of Presentation (Details) [Line Items]
Percentage Of Total Revenue	14.90%		14.70%	17.80%	13.90%
Hawaii Electric Light Company [Member]
Note 1 - General and Basis of Presentation (Details) [Line Items]
Percentage Of Total Revenue	8.60%		10.30%	8.90%	9.90%
Kenya Power And Lighting Co Limited [Member]
Note 1 - General and Basis of Presentation (Details) [Line Items]
Percentage Of Total Revenue	10.30%		7.80%	9.50%	7.60%
Domestic Tax Authority [Member]
Note 1 - General and Basis of Presentation (Details) [Line Items]
Cash, Cash Equivalents, and Short-term Investments	18,792,000			18,792,000		41,231,000
Deposit Insurance Per Depositor (in Dollars per Item)	250,000			250,000
Foreign Tax Authority [Member]
Note 1 - General and Basis of Presentation (Details) [Line Items]
Cash, Cash Equivalents, and Short-term Investments	18,551,000			18,551,000		33,215,000
Accounts Receivable, Net, Current	33,070,000			33,070,000		17,606,000
Reclassification out of Accumulated Other Comprehensive Income [Member]
Note 1 - General and Basis of Presentation (Details) [Line Items]
Interest Expense	68,000		76,000	136,000	150,000
Income Tax Expense (Benefit)	26,000		29,000	52,000	57,000
Deferred Income Tax Charge [Member]
Note 1 - General and Basis of Presentation (Details) [Line Items]
Valuation Allowances and Reserves, Adjustments		3,100,000				6,600,000
Property, Plant and Equipment [Member]
Note 1 - General and Basis of Presentation (Details) [Line Items]
Valuation Allowances and Reserves, Adjustments						$ 26,100,000