Leases - Lease Asset and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Lease Asset and Liabilities [Abstract]
Operating Lease, Right-of-Use Asset	$ 73,429	$ 75,049
Operating Lease, Liability, Current	1,514	1,296
Operating Lease, Liability, Noncurrent	78,965	79,468
Operating Lease, Liability	$ 80,479	$ 80,764
Operating Lease, Weighted Average Remaining Lease Term	17 years 2 months 12 days	18 years 2 months 12 days
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 7,364
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,495
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,369
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,493
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,637
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,913
Lessee, Operating Lease, Liability, Payments, Due	146,271
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	65,792
Operating Lease, Liability	80,479	$ 80,764
Operating Lease, Liability, Current	1,514	1,296
Operating Lease, Liability, Noncurrent	78,965	79,468
Lease Not Yet Commenced [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	146,271
Leases Cash Flow [Abstract]
Operating Lease, Payments	7,057	6,898	$ 4,597
Finance Lease, Principal Payments	524	801	835
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	977	223	78,590
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 270	$ 314	1,386
Finance Leases [Abstract]
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Total property, plant, and equipment, net	Total property, plant, and equipment, net
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 7,364
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,495
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,369
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,493
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,637
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,913
Lessee, Operating Lease, Liability, Payments, Due	146,271
Regulatory Assets, Noncurrent	340,432	$ 314,579
Finance Lease, Liability, to be Paid	0
Northwest Natural Gas Company [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating Lease, Right-of-Use Asset	72,720	74,987
Operating Lease, Liability, Current	1,363	1,273
Operating Lease, Liability, Noncurrent	78,345	79,431
Operating Lease, Liability	$ 79,708	$ 80,704
Operating Lease, Weighted Average Discount Rate, Percent	7.30%	7.20%
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 7,169
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,299
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,185
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,353
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,530
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,901
Lessee, Operating Lease, Liability, Payments, Due	145,437
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	65,729
Operating Lease, Liability	79,708	$ 80,704
Operating Lease, Liability, Current	1,363	1,273
Operating Lease, Liability, Noncurrent	78,345	79,431
Lease Not Yet Commenced [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	145,437
Leases Cash Flow [Abstract]
Operating Lease, Payments	6,993	6,840	4,466
Finance Lease, Principal Payments	524	801	835
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	309	223	78,539
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	270	314	1,386
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	7,169
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,299
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,185
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,353
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,530
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,901
Lessee, Operating Lease, Liability, Payments, Due	145,437
Regulatory Assets, Noncurrent	340,407	314,539
Corporate, Non-Segment [Member] | Northwest Holdings Other [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating Lease, Right-of-Use Asset	709	62
Operating Lease, Liability, Current	151	23
Operating Lease, Liability, Noncurrent	620	37
Operating Lease, Liability	771	60
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	195
Lessee, Operating Lease, Liability, Payments, Due Year Two	196
Lessee, Operating Lease, Liability, Payments, Due Year Three	184
Lessee, Operating Lease, Liability, Payments, Due Year Four	140
Lessee, Operating Lease, Liability, Payments, Due Year Five	107
Lessee, Operating Lease, Liability, Payments, Due after Year Five	12
Lessee, Operating Lease, Liability, Payments, Due	834
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	63
Operating Lease, Liability	771	60
Operating Lease, Liability, Current	151	23
Operating Lease, Liability, Noncurrent	620	37
Lease Not Yet Commenced [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	834
Leases Cash Flow [Abstract]
Operating Lease, Payments	64	58	131
Finance Lease, Principal Payments	0	0	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	668	0	51
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	0	$ 0	$ 0
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	195
Lessee, Operating Lease, Liability, Payments, Due Year Two	196
Lessee, Operating Lease, Liability, Payments, Due Year Three	184
Lessee, Operating Lease, Liability, Payments, Due Year Four	140
Lessee, Operating Lease, Liability, Payments, Due Year Five	107
Lessee, Operating Lease, Liability, Payments, Due after Year Five	12
Lessee, Operating Lease, Liability, Payments, Due	$ 834
Maximum [Member]
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Term of Contract	17 years