Note 5 - Fair Value of Financial Instruments (Details) - Fair Value Information for Financial Assets and Liabilities, as well as Cost or Amortized Cost (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Current assets:
Cash equivalents (including restricted cash accounts)	$ 67,234		$ 54,298
Derivatives:
Asset Net	71,681		60,955
Put Option [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives:
Derivative Assets		[1]		[1]
Put Option [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives:
Derivative Assets	142	[1]	1,842	[1]
Put Option [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives:
Derivative Assets		[1]		[1]
Put Option [Member]
Derivatives:
Derivative Assets	142	[1]	1,842	[1]
Put Option [Member] | Portion at Other than Fair Value Measurement [Member]
Derivatives:
Derivative Assets		[1]		[1]
Forward Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives:
Derivative Assets		[2]		[2]
Forward Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives:
Derivative Assets	2,952	[2]	1,675	[2]
Forward Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives:
Derivative Assets		[2]		[2]
Forward Contracts [Member]
Derivatives:
Derivative Assets	2,952	[2]	1,675	[2]
Forward Contracts [Member] | Portion at Other than Fair Value Measurement [Member]
Derivatives:
Derivative Assets		[2]		[2]
Natural Gas Price Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives:
Derivative Assets		[3]		[3]
Natural Gas Price Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives:
Derivative Assets	1,353	[3]	2,804	[3]
Natural Gas Price Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives:
Derivative Assets		[3]		[3]
Natural Gas Price Swap [Member]
Derivatives:
Derivative Assets	1,353	[3]	2,804	[3]
Natural Gas Price Swap [Member] | Portion at Other than Fair Value Measurement [Member]
Derivatives:
Derivative Assets		[3]		[3]
Crude Oil Price Swap [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives:
Derivative Assets				[4]
Crude Oil Price Swap [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives:
Derivative Assets			336	[4]
Crude Oil Price Swap [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives:
Derivative Assets				[4]
Crude Oil Price Swap [Member]
Derivatives:
Derivative Assets			336	[4]
Crude Oil Price Swap [Member] | Portion at Other than Fair Value Measurement [Member]
Derivatives:
Derivative Assets				[4]
Fair Value, Inputs, Level 1 [Member]
Current assets:
Cash equivalents (including restricted cash accounts)	67,234		54,298
Derivatives:
Asset Net	67,234		54,298
Fair Value, Inputs, Level 2 [Member]
Derivatives:
Asset Net	4,447		6,657
Portion at Other than Fair Value Measurement [Member]
Current assets:
Cash equivalents (including restricted cash accounts)	67,234		54,298
Derivatives:
Asset Net	$ 67,234		$ 54,298

[1] This amount relates to derivatives which represent European put transactions on oil prices, valued primarily based on observable inputs, including forward and spot prices for related commodity indices, and are included within "prepaid expenses and other" in the condensed consolidated balance sheet with the corresponding gain or loss being recognized within "electricity revenues" in the condensed consolidated statement of operations and comprehensive income (loss).

[2] This amount relates to derivatives which represent currency forward contracts, valued primarily based on observable inputs, including forward and spot prices for currencies, netted against contracted rates and then multiplied against notational amounts, and are included within "prepaid expenses and other" in the condensed consolidated balance sheet with the corresponding gain or loss being recognized within "foreign currency translation and transaction gains (losses)" in the condensed consolidated statement of operations and comprehensive income (loss).

[3] This amount relates to derivatives which represent swap contracts on natural gas prices, valued primarily based on observable inputs, including forward and spot prices for related commodity indices, and are included within "prepaid expenses and other" in the condensed consolidated balance sheet with the corresponding gain or loss being recognized within "electricity revenues" in the condensed consolidated statement of operations and comprehensive income (loss).

[4] This amount relates to derivatives which represent swap contracts on oil prices, valued primarily based on observable inputs, including forward and spot prices for related commodity indices, and are included within "prepaid expenses and other" in the condensed consolidated balance sheet with the corresponding gain or loss being recognized within "electricity revenues" in the condensed consolidated statement of operations and comprehensive income (loss).