Note 1 - General and Basis of Presentation (Tables)

3 Months Ended

Mar. 31, 2024

Notes Tables

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]

Trade receivables and others (1)	$	4.4
Deferred income taxes		3.1
Property, plant and equipment and construction-in-process (2)		197.7
Operating lease right of use		1.2
Other long-term assets		0.2
Intangible assets (3)		23.6
Goodwill (4)		60.7
Total assets acquired	$	290.9
Accounts payable, accrued expenses and others	$	1.5
Other current liabilities		1.8
Operating lease liabilities		1.2
Other long-term liabilities		5.0
Asset retirement obligation		6.8
Total liabilities assumed	$	16.3
Total assets acquired, and liabilities assumed, net	$	274.6

Business Acquisition, Pro Forma Information [Table Text Block]

	Pro forma for the Three Months Ended March 31,
	2024		2023
	(Dollars in millions)
Electricity revenues	$	191.3	$	179.8
Total revenues	$	224.2	$	194.7
Net income attributable to the Company's stockholders	$	39.9	$	27.7

Schedule of Cash and Cash Equivalents [Table Text Block]

	March 31,		December 31,
	2024		2023
	(Dollars in thousands)
Cash and cash equivalents	$	201,506	$	195,808
Restricted cash and cash equivalents		97,455		91,962
Total Cash and cash equivalents and restricted cash and cash equivalents	$	298,961	$	287,770

Schedules of Concentration of Risk, by Risk Factor [Table Text Block]

	Three Months Ended March 31,
	2024			2023
Southern California Public Power Authority (“SCPPA”)		24.7	%		26.7	%
Sierra Pacific Power Company and Nevada Power Company		16.8			18.9
Kenya Power and Lighting Co. Ltd. ("KPLC")		12.2			14.5

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

	Three Months Ended March 31,
	2024		2023
	(Dollars in thousands)
Beginning balance of the allowance for expected credit losses	$	90	$	90
Change in the provision for expected credit losses for the period		73		—
Ending balance of the allowance for expected credit losses	$	163	$	90

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

	March 31,			December 31,
	2024			2023
	(Dollars in thousands)
Contract assets (*)	$	23,616		$	18,367
Contract liabilities (*)	$	(21,376	)	$	(18,669	)

Operating Lease, Lease Income [Table Text Block]

	Three Months Ended March 31,
	2024		2023
	(Dollars in thousands)
Lease income relating to lease payments from operating leases	$	147,101	$	137,621