Accounting For Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense

	2021		2020			2019
Current income tax expense (benefit)	$	807	$	(37,913	)	$	16,276
Deferred income tax expense		11,224		44,964			15,098
Total income tax expense	$	12,031	$	7,051		$	31,374

Schedule of Effective Income Tax Rate Reconciliation

	2021					2020					2019
Federal income taxes at statutory rates	$	33,467		21.0	%	$	28,673		21.0	%	$	47,909		21.0	%
Increase (decrease) in tax resulting from:
Tax effect of regulatory treatment of utility    plant differences		(13,820	)	(8.7	)		(12,893	)	(9.4	)		(9,967	)	(4.3	)
State income tax expense		1,385		0.8			814		0.6			1,465		0.6
Acquisition costs		—		—			—		—			(1,712	)	(0.7	)
Flow through related to deduction of meters     and mixed service costs (1)		(8,678	)	(5.4	)		—		—			—		—
Non-plant excess deferred turnaround (2)		—		—			(8,476	)	(6.2	)		(5,690	)	(2.5	)
Tax loss on sale of METALfx		—		—			—		—			(1,272	)	(0.6	)
Customer refunds related to prior years at 35 percent		—		—			(1,189	)	(0.9	)		—		—
Other		(323	)	(0.2	)		122		0.1			641		0.3
Total income tax expense	$	12,031		7.5	%	$	7,051		5.2	%	$	31,374		13.8	%

(1)With the approval of the Idaho and Washington general rate cases in 2021, a change in tax methodology resulted in recognizing a flow through benefit related to meters and mixed service costs.

(2)In March 2020, the WUTC approved an all-party settlement agreement related to electric tax benefits that were set aside for Colstrip in the 2020 general rate case order. In the approved settlement agreement, the parties agreed to utilize $10.9 million ($8.4 million when tax-effected) of the electric benefits to offset costs associated with accelerating the depreciation of Colstrip Units, to reflect a remaining useful life through December 31, 2025. In the second quarter of 2020, the Company recorded a one-time increase to depreciation expense with an offsetting decrease to income tax expense.

In March 2019, the IPUC approved an all-party settlement agreement related to electric tax benefits that were set aside for Colstrip in the 2020 general rate case order. In the approved settlement agreement, the parties agreed to utilize $6.4 million ($5.1 million when tax-effected) of the electric benefits to offset costs associated with accelerating the depreciation of Colstrip, to reflect a remaining useful life through December 31, 2027. In the second quarter of 2019, the Company recorded a one-time increase to depreciation expense with an offsetting decrease to income tax expense.

Schedule of Deferred Income Tax Assets and Liabilities

The total net deferred income tax liability consisted of the following as of December 31 (dollars in thousands):

	2021			2020
Deferred income tax assets:
Regulatory liabilities	$	200,513		$	179,871
Tax credits and NOL carryforwards		64,994			57,516
Provisions for pensions		25,650			37,501
Other		38,181			42,641
Total gross deferred income tax assets		329,338			317,529
Valuation allowances for deferred tax assets		(9,626	)		(10,021	)
Total deferred income tax assets after valuation allowances		319,712			307,508
Deferred income tax liabilities:
Utility property, plant, and equipment		688,856			666,639
Regulatory assets		264,978			232,697
Other		8,587			2,884
Total deferred income tax liabilities		962,421			902,220
Net long-term deferred income tax liability	$	642,709		$	594,712