Investments $ in Thousands	Mar. 31, 2023 USD ($) employee numberOfProjects numberOfConnections	Dec. 31, 2022 USD ($)	Jul. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)
Schedule of Equity Method Investments [Line Items]
Life Insurance, Corporate or Bank Owned, Amount	$ 47,666	$ 49,358		$ 48,486
Gas reserves, noncurrent	22,229	22,970		25,364
Equity Method Investment, Aggregate Cost	23,716	23,376		22,416
Other investments	93,611	95,704		96,266
Total cumulative gas reserves investment	188,000
Deferred Taxes Related To Gas Reserves	4,400	5,200		11,000
Gas reserves, current	$ 3,300	3,400		5,200
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	$ 47,666	49,358		48,486
Gas reserves, noncurrent	22,229	22,970		25,364
Equity Method Investment, Aggregate Cost	8,207	7,782		7,947
Other investments	78,102	$ 80,110		$ 81,797
Lexington | Northwest Natural Gas Company [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Aggregate Cost	$ 8,200
Other Northwest Holdings [Member] | Avion Water
Schedule of Equity Method Investments [Line Items]
Ownership percentage of Avion	40.30%	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	$ 9,500
Equity Method Investment, Additional Underlying Equity in Net Assets			$ 1,000