Pension and Other Postretirement Benefits Costs (Tables)

12 Months Ended

Dec. 31, 2021

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	2021		2020		2021		2020
Reconciliation of change in benefit obligation:
Obligation at January 1	$	566,147	$	515,668	$	29,039	$	29,568
Service cost	6,982		6,614		238		258
Interest cost	13,447		16,161		684		905
Net actuarial (gain) loss	(18,587)		52,777		(688)		145
Benefits paid	(25,371)		(25,073)		(2,050)		(1,837)
Obligation at December 31	$	542,618	$	566,147	$	27,223	$	29,039
Reconciliation of change in plan assets:
Fair value of plan assets at January 1	$	373,932	$	313,051	$	—	$	—
Actual return on plan assets	38,712		54,600		—		—
Employer contributions	11,944		31,354		2,050		1,837
Benefits paid	(25,371)		(25,073)		(2,050)		(1,837)
Fair value of plan assets at December 31	$	399,217	$	373,932	$	—	$	—
Funded status at December 31	$	(143,401)	$	(192,215)	$	(27,223)	$	(29,039)

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	2021		2020		2019		2021		2020		2019		2021		2020		2019
Net actuarial (gain) loss	$	(32,258)	$	16,170	$	10,424	$	(688)	$	145	$	1,809	$	(812)	$	3,873	$	3,595
Amortization of:
Prior service (cost) credit	—		—		(7)		468		468		468		—		—		—
Actuarial loss	(21,250)		(18,627)		(14,057)		(645)		(607)		(369)		(1,225)		(923)		(648)
Total	$	(53,508)	$	(2,457)	$	(3,640)	$	(865)	$	6	$	1,908	$	(2,037)	$	2,950	$	2,947

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	2021		2020		2021		2020		2021		2020
Prior service cost (credit)	$	—	$	—	$	(333)	$	(801)	$	—	$	—
Net actuarial loss	112,182		164,446		5,834		7,167		15,399		17,434
Total	$	112,182	$	164,446	$	5,501	$	6,366	$	15,399	$	17,434

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	2021		2020
Beginning balance	$	(12,902)	$	(10,733)
Amounts reclassified to AOCL	812		(3,873)
Amounts reclassified from AOCL:
Amortization of actuarial losses	1,225		923
Total reclassifications before tax	2,037		(2,950)
Tax (benefit) expense	(539)		781
Total reclassifications for the period	1,498		(2,169)
Ending balance	$	(11,404)	$	(12,902)

Schedule of Allocation of Plan Assets

The following table presents the Pension Plan asset target allocation at December 31, 2021:

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	2021		2020		2019		2021		2020		2019
Service cost	$	6,981	$	6,614	$	6,308	$	238	$	258	$	244
Interest cost	13,448		16,161		18,684		684		905		1,116
Expected return on plan assets	(24,232)		(21,865)		(20,854)		—		—		—
Amortization of prior service cost (credit)	—		—		7		(468)		(468)		(468)
Amortization of net actuarial loss	22,475		19,550		14,704		645		607		368
Net periodic benefit cost	18,672		20,460		18,849		1,099		1,302		1,260
Amount allocated to construction	(3,015)		(2,798)		(2,493)		(93)		(98)		(86)
Net periodic benefit cost charged to expense	15,657		17,662		16,356		1,006		1,204		1,174
Regulatory pension disallowance	—		—		10,500		—		—		—
Amortization of regulatory balancing account	7,131		7,131		16,841		—		—		—
Net amount charged to expense	$	22,788	$	24,793	$	43,697	$	1,006	$	1,204	$	1,174

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
	2021		2020		2019		2021		2020		2019
Assumptions for net periodic benefit cost:
Weighted-average discount rate	2.40	%	3.18	%	4.19	%	2.34	%	3.11	%	4.13	%
Rate of increase in compensation	3.50	%	3.50	%	3.25-3.50%		n/a		n/a		n/a
Expected long-term rate of return	7.25	%	7.25	%	7.50	%	n/a		n/a		n/a
Assumptions for year-end funded status:
Weighted-average discount rate	2.71	%	2.36	%	3.16	%	2.72	%	2.34	%	3.11	%
Rate of increase in compensation(1)	3.50 %		3.50-6.50%		3.50-6.50%		n/a		n/a		n/a
Expected long-term rate of return	7.00	%	7.25	%	7.25	%	n/a		n/a		n/a

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:
2020	31,362	$	1,837
2021	11,944	2,050
2022 (estimated)	2,335	1,654
Benefit Payments:
2019	23,160	1,774
2020	25,073	1,837
2021	25,371	2,050
Estimated Future Benefit Payments:
2022	23,210	1,654
2023	24,020	1,665
2024	24,728	1,654
2025	25,325	1,643
2026	25,824	1,606
2027-2031	133,617	7,640

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, 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, 2020
Investments	Level 1		Level 2		Level 3		Non-Published NAV(1)		Total
US equity	$	—	$	—	$	—	$	117,764	$	117,764
International / Global equity	39,114		—		—		78,092		117,206
Liability hedging	—		—		—		111,041		111,041
Opportunistic	—		—		—		25,625		25,625
Cash and cash equivalents	—		—		—		2,295		2,295
Total investments	$	39,114	$	—	$	—	$	334,817	$	373,931
							December 31,
							2021		2020
Receivables:
Accrued interest and dividend income							$	—	$	6,429
Total receivables							—		6,429
Liabilities:
Due to broker for securities purchased							—		6,429
Total investment in retirement trust							$	399,217	$	373,931

(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.