Derivative Instruments Notional Amounts - Northwest Natural Gas Company [Member] therm in Thousands, $ in Thousands	Mar. 31, 2022 USD ($) therm	Dec. 31, 2021 USD ($) therm	Mar. 31, 2021 USD ($) therm
Gas Year 2021-2022
Derivative [Line Items]
TargetHedgeAchieved	79.00%
Gas Year 2021-2022 | Oregon [Member]
Derivative [Line Items]
TargetHedgeAchieved	82.00%
Gas Year 2021-2022 | WASHINGTON
Derivative [Line Items]
TargetHedgeAchieved	57.00%
Financial [Member] | Gas Year 2021-2022 | Oregon [Member]
Derivative [Line Items]
TargetHedgeAchieved	62.00%
Financial [Member] | Gas Year 2021-2022 | WASHINGTON
Derivative [Line Items]
TargetHedgeAchieved	44.00%
Physical [Member] | Gas Year 2021-2022 | Oregon [Member]
Derivative [Line Items]
TargetHedgeAchieved	19.00%
Physical [Member] | Gas Year 2021-2022 | WASHINGTON
Derivative [Line Items]
TargetHedgeAchieved	13.00%
Natural Gas Therms [Member] | Financial [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	449,710	618,815	597,495
Natural Gas Therms [Member] | Physical [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	317,840	431,628	187,595
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount | $	$ 5,216	$ 6,268	$ 5,954