Note 5 - Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2019

Notes Tables

Fair Value, by Balance Sheet Grouping [Table Text Block]

				March 31, 2019
				Fair Value
	Carrying Value at March 31, 2019			Total			Level 1		Level 2		Level 3
	(Dollars in thousands)
Assets:
Current assets:
Cash equivalents (including restricted cash accounts)	$	21,552		$	21,552		$	21,552	$	—	$	—
Derivatives:
Contingent receivable (1)		101			101			—		—		101
Currency forward contracts (2)		169			169			—		169		—
Liabilities:
Current liabilities:
Derivatives:
Contingent payable  (1)		(3,351	)		(3,351	)		—		—		(3,351	)
	$	18,471		$	18,471		$	21,552	$	169	$	(3,250	)

				December 31, 2018
				Fair Value
	Carrying Value at December 31, 2018			Total			Level 1		Level 2			Level 3
	(Dollars in thousands)
Assets
Current assets:
Cash equivalents (including restricted cash accounts)	$	18,787		$	18,787		$	18,787	$	—		$	—
Derivatives:
Contingent receivable (1)		104			104			—		—			104
Liabilities:
Current liabilities:
Derivatives:
Contingent payable  (1)		(3,424	)		(3,424	)		—		—			(3,424	)
Currency forward contracts (2)		(1,040	)		(1,040	)		—		(1,040	)		—
	$	14,427		$	14,427		$	18,787	$	(1,040	)	$	(3,320	)

Derivative Instruments, Gain (Loss) [Table Text Block]

		Amount of recognized gain (loss)
Derivatives not designated as hedging instruments	Location of recognized gain (loss)	Three Months Ended March 31,
		2019		2018
Currency forward contracts	Derivative and foreign currency and transaction gains (losses)	$	1,083	$	(546	)
		$	1,083	$	(546	)

Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]

	Fair Value				Carrying Amount
	March 31, 2019		December 31, 2018		March 31, 2019		December 31, 2018
	(Dollars in millions)				(Dollars in millions)
Olkaria III Loan - OPIC		210.0		211.8		206.1		210.6
Olkaria IV Loan - DEG 2		48.6		47.2		47.5		47.5
Olkaria IV Loan - DEG 3		42.5		—		41.5		—
Platanares Loan - OPIC		118.5		119.1		110.6		112.7
Amatitlan Loan		29.0		29.9		28.9		29.8
Senior Secured Notes:
OrCal Geothermal Inc. ("OrCal")		19.2		19.0		18.7		18.7
OFC 2 LLC ("OFC 2")		213.4		214.5		213.2		217.8
Don A. Campbell 1 ("DAC 1")		78.6		78.8		81.7		83.3
USG Prudential - NV		29.9		29.4		27.8		27.8
USG Prudential - ID		18.0		18.6		18.4		18.9
USG DOE		47.3		48.3		49.8		51.4
Senior Unsecured Bonds		199.3		199.4		204.3		204.3
Senior Unsecured Loan		153.6		102.2		150.0		100.0
Other long-term debt		5.3		5.4		6.2		6.2

Fair Value, Liabilities Measured on Recurring and Nonrecurring Basis [Table Text Block]

	Level 1		Level 2		Level 3		Total
	(Dollars in millions)
Olkaria III - OPIC		—		—		210.0		210.0
Olkaria IV - DEG 2		—		—		48.6		48.6
Olkaria IV Loan - DEG 3		—		—		42.5		42.5
Platanares Loan - OPIC		—		—		118.5		118.5
Amatitlan Loan		—		29.0		—		29.0
Senior Secured Notes:
OrCal Senior Secured Notes		—		—		19.2		19.2
OFC 2 Senior Secured Notes		—		—		213.4		213.4
DAC 1 Senior Secured Notes		—		—		78.6		78.6
USG Prudential - NV		—		—		29.9		29.9
USG Prudential - ID		—		—		18.0		18.0
USG DOE		—		—		47.3		47.3
Senior Unsecured Bonds		—		—		199.3		199.3
Senior Unsecured Loan		—		—		153.6		153.6
Other long-term debt		—		—		5.3		5.3
Revolving lines of credit		—		60.9		—		60.9
Deposits		11.9		—		—		11.9

	Level 1		Level 2		Level 3		Total
	(Dollars in millions)
Olkaria III Loan - OPIC		—		—		211.8		211.8
Olkaria IV - DEG 2		—		—		47.2		47.2
Platanares Loan - OPIC		—		—		119.1		119.1
Amatitlan Loan		—		29.9		—		29.9
Senior Secured Notes:
OrCal Senior Secured Notes		—		—		19.0		19.0
OFC 2 Senior Secured Notes		—		—		214.5		214.5
DAC 1 Senior Secured Notes		—		—		78.8		78.8
USG Prudential - NV		—		—		29.4		29.4
USG Prudential - ID		—		—		18.6		18.6
USG DOE		—		—		48.3		48.3
Senior Unsecured Bonds		—		—		199.4		199.4
Senior Unsecured Loan		—		—		102.2		102.2
Other long-term debt		—		—		5.4		5.4
Revolving lines of credit		—		159.0		—		159.0
Deposits		12.0		—		—		12.0