Leases - Lease Expense - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Lease Expense [Abstract]
Operating Lease, Expense	$ 1,907	$ 1,815
Short-term Lease, Cost	$ 81	80
Lessee, Operating Lease, Maximum Term of Short-term Leases not recorded on the Balance Sheet	12 months
Minimum [Member]
Operating Lease Terms [Abstract]
Lessee, Operating Lease, Term of Contract	8 months
Maximum [Member]
Operating Lease Terms [Abstract]
Lessee, Operating Lease, Term of Contract	16 years
Northwest Natural Gas Company [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 1,862	1,775
Short-term Lease, Cost	81	80
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 45	$ 40