Income taxes (Tables)

12 Months Ended

Dec. 31, 2024

Income Tax Disclosure [Abstract]

Summary of difference between statutory federal income tax rate on income before income taxes and effective income tax rate

The difference between the statutory federal income tax rate on income before income taxes and our effective income tax rate is summarized as follows:

	2024		2023		2022
Statutory federal income tax rate	21.0	%	21.0	%	21.0	%
Patronage exclusion	(21.0)	%	(21.0)	%	(21.0)	%
Effective income tax rate	0.0	%	0.0	%	0.0	%

Schedule of components of net deferred tax assets and liabilities

The components of our net deferred tax assets and liabilities as of December 31, 2024 and 2023 were as follows:

	(dollars in thousands)
	2024		2023
Deferred tax assets
Net operating losses	$	157,190	$	109,447
Obligation related to asset retirements	319,040		375,530
Advance payments	142,949		176,956
Other regulatory liabilities	36,973		23,652
Other assets	13,026		30,085
Deferred tax assets	669,178		715,670
Less: Valuation allowance	—		—
Net deferred tax assets	$	669,178	$	715,670
Deferred tax liabilities
Fixed assets and intangibles	$	(175,777)	$	(154,219)
Right-of-use assets-finance leases	(75,508)		(77,923)
Other regulatory asset	(338,048)		(373,802)
Other liabilities	(19,024)		(15,679)
Deferred tax liabilities	(608,357)		(621,623)
Net deferred tax assets (liabilities)	$	60,821	$	94,047
Less: Patronage exclusion	(60,821)		(94,047)
Net deferred taxes	$	—	$	—