Note 1 - Business and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Cash and Cash Equivalents [Table Text Block]

	December 31,
	2018		2017		2016
	(Dollars in thousands)
Cash and cash equivalents	$	98,802	$	47,818	$	230,214
Restricted cash and cash equivalents		78,693		48,825		34,262
Total Cash and cash equivalents and restricted cash and cash equivalents	$	177,495	$	96,643	$	264,476

Schedule Of Estimated Useful Lives [Table Text Block]

Buildings (in years)		25
Leasehold improvements (in years)	15	-	20
Machinery and equipment — manufacturing and drilling (in years)		10
Machinery and equipment — computers (in years)	3	-	5
Office equipment — furniture and fixtures (in years)	5	-	15
Office equipment — other (in years)	5	-	10
Automobiles (in years)	5	-	7

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

	Year Ended December 31,
	2018		2017		2016
	(In thousands)
Weighted average number of shares used in computation of basic earnings per share		50,643		50,110		49,469
Add:
Additional shares from the assumed exercise of employee stock options		326		659		671
Weighted average number of shares used in computation of diluted earnings per share		50,969		50,769		50,140

Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]

	(Dollars in millions)
Electricity segment revenues	$	–
Product segment revenues		–
Other segment revenues		–
Investment in an unconsolidated company as of January 1, 2018		24.0

	Year Ended December 31, 2018
	(Dollars in thousands)
Electricity Revenues accounted under ASC 840, Leases	$	481,619
Electricity, Product and Other revenues accounted under ASC 606		237,648
Total consolidated revenues	$	719,267

	Year ended December 31, 2018 under previous standard		Effect of the New Revenue Standard		As reported for the year ended December 31, 2018
	(Dollars in thousands)
Equity in earnings (losses) of investees, net	$	5,615	$	2,048	$	7,663
Income from continuing operations		108,063		2,048		110,111
Net income attributable to the Company’s stockholders		95,918		2,048		97,966
Retained earnings as of the end of the period		420,174		2,048		422,222

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

	December 31,			December 31,
	2018			2017
	(Dollars in thousands)
Contract assets (*)	$	42,130		$	40,945
Contract liabilities (*)		(18,402	)		(20,241	)
Contract assets, net	$	23,728		$	20,704

	Contract assets			Contract liabilities
	(Dollars in thousands)
Recognition of contract liabilities as revenue as a result of performance obligations satisfied	$	-		$	33,349
Cash received in advance for which revenues have not yet recognized, net expenditures made		-			(38,162	)
Reduction of contract assets as a result of rights to consideration becoming unconditional		(128,659	)		-
Contract assets recognized, net of recognized receivables		136,496			-
Net change in contract assets and contract liabilities		7,837			(4,813	)