Note 1 - Business and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Schedule of Cash and Cash Equivalents [Table Text Block]

	December 31,
	2021		2020		2019
	(Dollars in thousands)
Cash and cash equivalents	$	239,278	$	448,252	$	71,173
Restricted cash and cash equivalents		104,166		88,526		81,937
Total cash and cash equivalents and restricted cash and cash equivalents	$	343,444	$	536,778	$	153,110

Schedule Of Estimated Useful Lives [Table Text Block]

		Years
Buildings		25
Leasehold improvements	15	-	30
Machinery and equipment — manufacturing and drilling		10
Machinery and equipment — computers	3	-	5
Energy storage equipment		15
Office equipment — furniture and fixtures	5	-	15
Office equipment — other	5	-	10
Vehicles	5	-	7

Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block]

	December 31,			December 31,
	2021			2020
	(Dollars in thousands)
Contract assets (*)	$	9,692		$	24,544
Contract liabilities (*)	$	(9,248	)	$	(11,179	)

	Years Ended December 31,
	2021						2020
	Contract assets			Contract liabilities			Contract assets			Contract liabilities
	(Dollars in thousands)
Recognition of contract liabilities as revenue as a result of performance obligations satisfied	$	—		$	3,566		$	—		$	5,336
Cash received in advance for which revenues have not yet recognized, net of expenditures made		—			(2,146	)		—			(11,177	)
Reduction of contract assets as a result of rights to consideration becoming unconditional		(43,518	)		—			(145,548	)		—
Contract assets recognized, net of recognized receivables		29,177			—			129,144			—
Net change in contract assets and contract liabilities	$	(14,341	)	$	1,420		$	(16,404	)	$	(5,841	)

Accounting Standards Update and Change in Accounting Principle [Table Text Block]

	Year Ended December 31,
	2021		2020		2019
	(Dollars in thousands)
Electricity revenues accounted under lease accounting	$	502,355	$	473,260	$	479,059
Electricity, Product and Energy Storage revenues accounted under ASC 606		160,729		232,082		266,985
Total consolidated revenues	$	663,084	$	705,342	$	746,044

Accounts Receivable, Allowance for Credit Loss [Table Text Block]

	Years Ended December 31,
	2021			2020
	(Dollars in thousands)
Beginning balance of the allowance for expected credit losses	$	597		$	755
Change in the provision for expected credit losses for the period		(507	)		(158	)
Ending balance of the allowance for expected credit losses	$	90		$	597

Schedule of Weighted Average Number of Shares [Table Text Block]

	Year Ended December 31,
	2021		2020		2019
	(In thousands)
Weighted average number of shares used in computation of basic earnings per share		56,004		51,567		50,867
Add:
Additional shares from the assumed exercise of employee stock options		398		370		360
Weighted average number of shares used in computation of diluted earnings per share		56,402		51,937		51,227

Redeemable Noncontrolling Interest [Table Text Block]

	2021			2020
	(Dollars in thousands)
Redeemable noncontrolling interest as of January 1,	$	9,830		$	9,250
Redeemable noncontrolling interest in results of operation of a consolidated subsidiary		619			1,330
Cash paid to noncontrolling interest		(268	)		(1,779	)
Currency translation adjustments		(852	)		1,029
Redeemable noncontrolling interest as of December 31,	$	9,329		$	9,830

ROA Asset [Member]

Notes Tables

Schedule Of Estimated Useful Lives [Table Text Block]

	(in years)
Vehicles		4	-	5
Building			15