Investments $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) numberOfProjects employee numberOfConnections	Dec. 31, 2021 USD ($)	Mar. 31, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Life Insurance, Corporate or Bank Owned, Amount	$ 48,486	$ 48,178	$ 47,411
Gas reserves, noncurrent	25,364	26,608	31,600
Equity Method Investment, Aggregate Cost	22,416	14,492	23
Other investments	96,266	89,278	79,034
Total cumulative gas reserves investment	188,000
Deferred Taxes Related To Gas Reserves	11,000	6,900	9,800
Gas reserves, current	$ 5,200	5,400	10,700
Investments, Number of RNG Development Projects | numberOfProjects	4
Northwest Natural Gas Company [Member]
Schedule of Equity Method Investments [Line Items]
Life Insurance, Corporate or Bank Owned, Amount	$ 48,486	48,178	47,411
Gas reserves, noncurrent	25,364	26,608	31,600
Equity Method Investment, Aggregate Cost	7,947	0	0
Other investments	81,797	74,786	$ 79,011
Lexington | Northwest Natural Gas Company [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Aggregate Cost	7,900
Deconsolidation, Gain (Loss), Amount	$ 0
Other Northwest Holdings [Member] | Avion Water
Schedule of Equity Method Investments [Line Items]
Ownership percentage of Avion	37.30%
Investment balance in Avion		$ 14,500
Equity Method Investment, Number of Customer Connections | numberOfConnections	15,000
Equity Method Investment, Number of Employees | employee	35
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ 10,400