Leases - Lease Expense - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Lease Expense [Abstract]
Operating Lease, Expense	$ 1,830	$ 1,749	$ 3,645	$ 3,483
Short-term Lease, Cost	$ 278	416	$ 358	579
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	$ 1,790	1,741	$ 3,565	3,468
Short-term Lease, Cost	278	416	358	579
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 40	$ 8	$ 80	$ 15