Commitments and Contingencies - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) therms	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Leases [Abstract]
Property, Plant and Equipment, Gross	$ 3,997,243	$ 3,734,039
Other Liabilities, Noncurrent	$ 114,979	120,767
Archaea RNG Agreement
Leases [Abstract]
Fixed Fee Purchase Obligation, Period	21 years
Maximum [Member]
Leases [Abstract]
Lessee, Operating Lease, Term of Contract	18 years
Maximum [Member] | Archaea RNG Agreement
Leases [Abstract]
Fixed Fee Purchase Obligation, Therms | therms	10,000,000
Northwest Natural Gas Company [Member]
Leases [Abstract]
Unrecorded Unconditional Purchase Obligation, Purchases	$ 82,900	81,800	$ 82,200
Unrecorded Unconditional Purchase Obligation Offsetting Sales	7,700	4,800	$ 4,300
Property, Plant and Equipment, Gross	3,931,640	3,683,776
Other Liabilities, Noncurrent	$ 113,934	$ 120,309