Investments $ in Thousands	Mar. 31, 2024 USD ($) numberOfConnections employee	Jan. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Jul. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Life Insurance, Corporate or Bank Owned, Amount	$ 45,937		$ 45,713		$ 47,666
Gas reserves, noncurrent	20,406		20,893		22,229
Equity Method Investment, Aggregate Cost	17,738		36,345		23,716
Other investments	84,081		102,951		93,611
Total cumulative gas reserves investment	188,000
Deferred Taxes Related To Gas Reserves	3,800		4,000		4,400
Gas reserves, current	2,200		2,300		3,300
Northwest Natural Gas Company [Member]
Schedule of Equity Method Investments [Line Items]
Life Insurance, Corporate or Bank Owned, Amount	45,937		45,713		47,666
Gas reserves, noncurrent	20,406		20,893		22,229
Equity Method Investment, Aggregate Cost	0		19,539		8,207
Other investments	$ 66,343		$ 86,145		$ 78,102
Other Northwest Holdings [Member] | Avion Water
Schedule of Equity Method Investments [Line Items]
Ownership percentage of Avion		45.60%		43.10%		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	$ 9,800
Equity Method Investment, Additional Underlying Equity in Net Assets		$ 1,000		$ 1,000		$ 1,000