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Number of Net Investments in Sales-Type Leases

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The percentage used to adjust customer rates for differences between forecasted and actual gas costs from the prior year.

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The weighted average depreciation rates for general plant

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The weighted average depreciation rates for transmission and distribution plant

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The weighted average depreciation rates for utility storage plant

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Amount of allowance for credit loss on accounts receivable.

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Amount of increase in allowance for credit loss on accounts receivable, from recovery.

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Amount of direct write-downs of accounts receivable charged against the allowance.

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Carrying value as of the balance sheet date of payments made in excess of existing cash balances, which will be honored by the bank but reflected as a loan to the entity. Overdrafts generally have a very short time frame for correction or repayment and are therefore more similar to short-term bank financing than trade financing.

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Carrying amount as of the balance sheet date of natural gas in storage, which is a mixture of gases (liquefied or otherwise), used for fuel and manufacturing purposes, which is ready for sale.

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Total loss recognized during the period from the impairment of goodwill plus the loss recognized in the period resulting from the impairment of the carrying amount of intangible assets, other than goodwill.

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Aggregated amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed. This amount is net of valuation reserves and adjustments.

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Effective rate, including composite rate, of cost of financing additions to qualifying regulated assets, commonly called allowance for funds used during construction.

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Composite depreciation rate for public utility plants in service.

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Amortization period for the recovery of regulatory asset, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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- Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
- Narrative (Details) $ in Thousands	Dec. 31, 2021 USD ($) numberOfLeases	Dec. 31, 2021 USD ($) numberOfLeases	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Industry Regulation [Abstract]
Regulatory Assets, Noncurrent	$ 314,579	$ 314,579	$ 348,927
COVID-19 Impact [Abstract]
Regulatory Assets, Noncurrent	314,579	$ 314,579	$ 348,927
Property, Plant and Accrued Asset Removal Costs [Abstract]
Weighted Average Depreciation Rates Transmission Distribution		2.60%
Weighted Average Depreciation Rates Gas Storage		2.00%
Weighted Average Depreciation Rates General Plant		6.20%
Weighted Average Depreciation Rates Intangible Other		6.10%
Public Utilities, AFUDC, Rate		0.70%	1.90%	3.90%
Revenue Recognition [Abstract]
Accrued unbilled revenue	82,169	$ 82,169	$ 57,949
Revenue Taxes [Abstract]
Utilities Operating Expense, Taxes		34,740	30,291	$ 30,325
Inventory Disclosure [Abstract]
Inventory, Raw Materials and Supplies, Net of Reserves	19,400	19,400	18,000
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	70,570	70,570	69,225
Goodwill and Intangible Asset Impairment	0
Allowance for Credit Loss [Line Items]
Accounts Receivable, Allowance for Credit Loss, Recovery		(1,925)
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		724
Accounts Receivable, Allowance for Credit Loss	$ 2,018	$ 2,018	3,219
Number of Net Investments in Sales-Type Leases \| numberOfLeases	2	2
Industrial
Allowance for Credit Loss [Line Items]
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		$ (79)
Accounts Receivable, Allowance for Credit Loss, Writeoff		(4)
Accounts Receivable, Allowance for Credit Loss	$ 67	67	142
Accrued unbilled and other
Allowance for Credit Loss [Line Items]
Accounts Receivable, Allowance for Credit Loss, Recovery		(177)
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		270
Accounts Receivable, Allowance for Credit Loss	313	313	220
Residential
Allowance for Credit Loss [Line Items]
Accounts Receivable, Allowance for Credit Loss, Recovery		(1,476)
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		783
Accounts Receivable, Allowance for Credit Loss	1,460	1,460	2,153
Commercial
Allowance for Credit Loss [Line Items]
Accounts Receivable, Allowance for Credit Loss, Recovery		(276)
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		(250)
Accounts Receivable, Allowance for Credit Loss	178	178	704
Accounts Payable [Member]
Cash and Cash Equivalents [Abstract]
Bank Overdrafts	0	0	4,400
Other Current Assets
Cash and Cash Equivalents [Abstract]
Restricted Cash and Cash Equivalents	8,561	8,561	5,286
COVID-19 Related Costs
Industry Regulation [Abstract]
Regulatory Assets, Noncurrent	8,600	8,600	4,800
COVID-19 Impact [Abstract]
Regulatory Assets, Noncurrent	8,600	$ 8,600	4,800
Northwest Natural Gas Company [Member]
Industry Regulation [Abstract]
Regulatory Liability, Amortization Period		12 months
Regulatory Asset, Amortization Period		12 months
Regulatory Assets, Noncurrent	314,539	$ 314,539	348,887
COVID-19 Impact [Abstract]
Regulatory Assets, Noncurrent	314,539	314,539	348,887
Revenue Recognition [Abstract]
Accrued unbilled revenue	82,028	82,028	57,890
Revenue Taxes [Abstract]
Utilities Operating Expense, Taxes		34,600	30,291	$ 30,325
Inventory Disclosure [Abstract]
Inventory - Gas	37,400	$ 37,400	$ 24,700
Northwest Natural Gas Company [Member] \| Oregon [Member]
Industry Regulation [Abstract]
Purchased Gas Adjustment Percentage		90.00%	90.00%	90.00%
Derivative Instruments and Hedging Activities Disclosure [Abstract]
PGA deferral rate		90.00%	90.00%	90.00%
Northwest Natural Gas Company [Member] \| Oregon [Member] \| Minimum [Member]
Industry Regulation [Abstract]
Purchased Gas Adjustment Percentage		80.00%
Derivative Instruments and Hedging Activities Disclosure [Abstract]
PGA deferral rate		80.00%
Impact on earnings from gas cost sharing		10.00%
Northwest Natural Gas Company [Member] \| Oregon [Member] \| Maximum [Member]
Industry Regulation [Abstract]
Purchased Gas Adjustment Percentage		90.00%
Derivative Instruments and Hedging Activities Disclosure [Abstract]
PGA deferral rate		90.00%
Impact on earnings from gas cost sharing		20.00%
Northwest Natural Gas Company [Member] \| WASHINGTON
Industry Regulation [Abstract]
Purchased Gas Adjustment Percentage		100.00%	100.00%	100.00%
Derivative Instruments and Hedging Activities Disclosure [Abstract]
PGA deferral rate		100.00%	100.00%	100.00%
Northwest Natural Gas Company [Member] \| Other Current Assets
Cash and Cash Equivalents [Abstract]
Restricted Cash and Cash Equivalents	$ 8,561	$ 8,561	$ 5,286
Asset Recoverable Gas Costs [Member] \| Northwest Natural Gas Company [Member]
Industry Regulation [Abstract]
Regulatory Liability, Amortization Period		12 months
Sales-type Lease [Member]
Allowance for Credit Loss [Line Items]
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		$ 0
Other Nonoperating Income (Expense) [Member]
Industry Regulation [Abstract]
Other Nonoperating Income		6,100	4,800
Other Nonoperating Expense		$ 1,300	$ 1,800
Natural Gas Distribution [Member]
Property, Plant and Accrued Asset Removal Costs [Abstract]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service		3.00%	3.00%	2.90%
Weighted-average depreciation rate, assets in service		3.00%	3.00%	2.90%
Natural Gas Distribution [Member] \| Operating Segments [Member]
Revenue Taxes [Abstract]
Utilities Operating Expense, Taxes		$ 34,600	$ 30,291	$ 30,325