Leases - Lease Expense - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Lease Expense [Abstract]
Operating Lease, Expense	$ 1,868	$ 1,774	$ 5,513	$ 5,257
Short-term Lease, Cost	$ 198	105	$ 556	684
Lessee, Operating Lease, Maximum Term of Short-term Leases not recorded on the Balance Sheet	12 months		12 months
Minimum [Member]
Operating Lease Terms [Abstract]
Lessee, Operating Lease, Term of Contract	3 months		3 months
Maximum [Member]
Operating Lease Terms [Abstract]
Lessee, Operating Lease, Term of Contract	17 years		17 years
Northwest Natural Gas Company [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 1,817	1,767	$ 5,382	5,235
Short-term Lease, Cost	198	105	556	684
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 51	$ 7	$ 131	$ 22