Income taxes (Tables)

12 Months Ended

Dec. 31, 2021

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:

	2021		2020		2019
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, 2021 and 2020 were as follows:

	(dollars in thousands)
	2021		2020
Deferred tax assets
Obligation related to asset retirements	$	331,311	$	286,546
Advance payments	175,077		112,394
Other regulatory liabilities	54,611		27,651
Other assets	24,838		17,424
Deferred tax assets	585,837		444,015
Less: Valuation allowance	—		—
Net deferred tax assets	$	585,837	$	444,015
Deferred tax liabilities
Fixed assets and intangibles	$	(40,655)	$	(132,520)
Right-of-Use assets-finance leases	(77,923)		(77,923)
Other regulatory asset	(338,291)		(207,186)
Other liabilities	(17,984)		(19,233)
Deferred tax liabilities	(474,853)		(436,862)
Net deferred tax assets/(liabilities)	$	110,984	$	7,153
Less: Patronage exclusion	(110,984)		(7,153)
Net deferred taxes	$	—	$	—