Pension and Other Postretirement Benefits Costs (Tables)

12 Months Ended

Dec. 31, 2022

Retirement Benefits [Abstract]

Schedule of Defined Benefit Plans Disclosures

The following table provides a reconciliation of the changes in NW Natural's benefit obligations and fair value of plan assets, as applicable, for NW Natural's pension and other postretirement benefit plans, excluding the Retirement K Savings Plan, and a summary of the funded status and amounts recognized in NW Holdings' and NW Natural's consolidated balance sheets as of December 31:

	Postretirement Benefit Plans
	Pension Benefits				Other Benefits
In thousands	2022		2021		2022		2021
Reconciliation of change in benefit obligation:
Obligation at January 1	$	542,618	$	566,147	$	27,223	$	29,039
Service cost	5,933		6,982		193		238
Interest cost	14,593		13,447		724		684
Net actuarial gain	(122,168)		(18,587)		(6,234)		(688)
Benefits paid	(27,563)		(25,371)		(2,026)		(2,050)
Obligation at December 31	$	413,413	$	542,618	$	19,880	$	27,223
Reconciliation of change in plan assets:
Fair value of plan assets at January 1	$	399,217	$	373,932	$	—	$	—
Actual return on plan assets	(93,703)		38,712		—		—
Employer contributions	2,353		11,944		2,026		2,050
Benefits paid	(27,563)		(25,371)		(2,026)		(2,050)
Fair value of plan assets at December 31	$	280,304	$	399,217	$	—	$	—
Funded status at December 31	$	(133,109)	$	(143,401)	$	(19,880)	$	(27,223)

Schedule Of Amounts Recognized In Regulatory Assets Or Other Comprehensive Income Loss

The following table presents amounts realized through regulatory assets or in other comprehensive loss (income) for the years ended December 31:

	Regulatory Assets												Other Comprehensive Loss (Income)
	Pension Benefits						Other Postretirement Benefits						Pension Benefits
In thousands	2022		2021		2020		2022		2021		2020		2022		2021		2020
Net actuarial (gain) loss	$	2,833	$	(32,258)	$	16,170	$	(6,234)	$	(688)	$	145	$	(5,706)	$	(812)	$	3,873
Amortization of:
Prior service credit	—		—		—		333		468		468		—		—		—
Actuarial loss	(11,531)		(21,250)		(18,627)		(426)		(645)		(607)		(1,081)		(1,225)		(923)
Total	$	(8,698)	$	(53,508)	$	(2,457)	$	(6,327)	$	(865)	$	6	$	(6,787)	$	(2,037)	$	2,950

Schedule Of Defined Benefit Plan Amounts In AOCL And Regulatory Assets

The following table presents amounts recognized in regulatory assets and accumulated other comprehensive loss (AOCL) at December 31:

	Regulatory Assets								AOCL
	Pension Benefits				Other Postretirement Benefits				Pension Benefits
In thousands	2022		2021		2022		2021		2022		2021
Prior service credit	$	—	$	—	$	—	$	(333)	$	—	$	—
Net actuarial loss (gain)	102,240		112,182		(826)		5,834		8,717		15,399
Total	$	102,240	$	112,182	$	(826)	$	5,501	$	8,717	$	15,399

Schedule of Amounts Recognized in Other Comprehensive Income (Loss)

The following table presents amounts recognized by NW Holdings and NW Natural in AOCL and the changes in AOCL related to NW Natural's non-qualified employee benefit plans:

	Year ended December 31,
In thousands	2022		2021
Beginning balance	$	(11,404)	$	(12,902)
Amounts reclassified to AOCL	5,706		812
Amounts reclassified from AOCL:
Amortization of actuarial losses	1,081		1,225
Total reclassifications before tax	6,787		2,037
Tax benefit	(1,797)		(539)
Total reclassifications for the period	4,990		1,498
Ending balance	$	(6,414)	$	(11,404)

Schedule of Allocation of Plan Assets

The following table presents the Pension Plan asset target allocation at December 31, 2022:

Asset Category	Target Allocation
Long government/credit	20	%
U.S. large cap equity	18
Non-U.S. equity	18
Absolute return strategies	12
U.S. small/mid cap equity	10
Real estate funds	7
High yield bonds	5
Emerging markets equity	5
Emerging market debt	5

Schedule of Net Benefit Costs

The following table provides the components of net periodic benefit cost for NW Natural's pension and other postretirement benefit plans for the years ended December 31:

	Pension Benefits						Other Postretirement Benefits
In thousands	2022		2021		2020		2022		2021		2020
Service cost	$	5,933	$	6,981	$	6,614	$	193	$	238	$	258
Interest cost	14,593		13,448		16,161		724		684		905
Expected return on plan assets	(25,698)		(24,232)		(21,865)		—		—		—
Amortization of prior service credit	—		—		—		(333)		(468)		(468)
Amortization of net actuarial loss	12,612		22,475		19,550		426		645		607
Net periodic benefit cost	7,440		18,672		20,460		1,010		1,099		1,302
Amount allocated to construction	(2,621)		(3,015)		(2,798)		(76)		(93)		(98)
Net periodic benefit cost charged to expense	4,819		15,657		17,662		934		1,006		1,204
Amortization of regulatory balancing account	7,131		7,131		7,131		—		—		—
Net amount charged to expense	$	11,950	$	22,788	$	24,793	$	934	$	1,006	$	1,204

Sensitivity Analysis Of Retirement Benefit Costs and Benefit Obligations

The following table provides the assumptions used in measuring periodic benefit costs and benefit obligations for the years ended December 31:

	Pension Benefits						Other Postretirement Benefits
	2022		2021		2020		2022		2021		2020
Assumptions for net periodic benefit cost:
Weighted-average discount rate	2.71	%	2.40	%	3.18	%	2.72	%	2.34	%	3.11	%
Rate of increase in compensation	3.50	%	3.50	%	3.50	%	n/a		n/a		n/a
Expected long-term rate of return	7.00	%	7.25	%	7.25	%	n/a		n/a		n/a
Assumptions for year-end funded status:
Weighted-average discount rate	5.18	%	2.71	%	2.36	%	5.19	%	2.72	%	2.34	%
Rate of increase in compensation(1)	4.00-6.00%		3.50	%	3.50-6.50%		n/a		n/a		n/a
Expected long-term rate of return	7.50	%	7.00	%	7.25	%	n/a		n/a		n/a

Defined Benefit Plan Estimated Future Employer Contributions Benefit Payments and Estimated Future Payments

The following table provides information regarding employer contributions and benefit payments for NW Natural's Pension Plan, non-qualified pension plans, and other postretirement benefit plans for the years ended December 31, and estimated future contributions and payments:

In thousands	Pension Benefits		Other Benefits
Employer Contributions:
2021	$	11,944	$	2,050
2022	2,353		2,026
2023 (estimated)	2,333		1,586
Benefit Payments:
2020	25,073		1,837
2021	25,371		2,050
2022	27,563		2,026
Estimated Future Benefit Payments:
2023	26,499		1,586
2024	27,029		1,591
2025	27,541		1,586
2026	27,981		1,560
2027	36,485		1,552
2028-2032	145,486		7,345

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

The following tables present the fair value of NW Natural's Pension Plan assets, including outstanding receivables and liabilities, of NW Natural's retirement trust fund

In thousands	December 31, 2022
Investments	Level 1		Level 2		Level 3		Non-Published NAV(1)		Total
US equity	$	—	$	—	$	—	$	68,729	$	68,729
International / Global equity	26,677		—		—		63,827		90,504
Liability hedging	—		—		—		94,823		94,823
Opportunistic	—		—		—		23,903		23,903
Cash and cash equivalents	—		—		—		2,345		2,345
Total investments	$	26,677	$	—	$	—	$	253,627	$	280,304
	December 31, 2021
Investments	Level 1		Level 2		Level 3		Non-Published NAV(1)		Total
US equity	$	—	$	—	$	—	$	121,090	$	121,090
International / Global equity	35,456		—		—		88,078		123,534
Liability hedging	—		—		—		118,464		118,464
Opportunistic	—		—		—		33,808		33,808
Cash and cash equivalents	—		—		—		2,321		2,321
Total investments	$	35,456	$	—	$	—	$	363,761	$	399,217
							December 31,
							2022		2021
Receivables:
Accrued interest and dividend income							$	7,703	$	—
Total receivables							7,703		—
Liabilities:
Due to broker for securities purchased							(7,701)		—
Total investment in retirement trust							$	280,306	$	399,217

(1) The fair value for these investments is determined using Net Asset Value per share (NAV) as of December 31, as a practical expedient, and therefore they are not classified within the fair value hierarchy. These investments primarily consist of institutional investment products, for which the NAV is generally not publicly available.