Leases - Lease Asset and Liabilities - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	$ 72,699	$ 74,416	$ 73,429
Operating lease liabilities current liabilities	1,700	1,303	1,514
Operating lease liabilities noncurrent liabilities	78,302	79,162	78,965
Total operating lease liabilities	$ 80,002	$ 80,465	$ 80,479
Operating Lease, Weighted Average Remaining Lease Term	17 years	18 years	17 years 2 months 12 days
Operating Lease, Weighted Average Discount Rate, Percent	7.30%	7.20%	7.30%
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	$ 144,456
Regulatory Assets, Noncurrent	311,419	$ 297,546	$ 340,432
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	5,550
Lessee, Operating Lease, Liability, to be Paid, Year One	7,495
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,368
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,493
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,637
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,913
Lessee, Operating Lease, Liability, Payments, Due	144,456
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	64,454
Total operating lease liabilities	80,002	80,465	80,479
Operating lease liabilities current liabilities	1,700	1,303	1,514
Operating lease liabilities noncurrent liabilities	78,302	79,162	78,965
Finance Lease, Liability, Payments, Due Next Twelve Months	0
Leases Cash Flow [Abstract]
Operating cash flows from operating leases	1,806	1,739
Finance Lease, Principal Payments	173	75
Operating leases	0	14
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	263	100
Finance Leases [Abstract]
Finance Lease, Liability	0
Finance Lease, Right-of-Use Asset	2,400	2,200	2,300
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	622	55	709
Operating lease liabilities current liabilities	162	17	151
Operating lease liabilities noncurrent liabilities	462	37	620
Total operating lease liabilities	624	54	771
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	786
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	148
Lessee, Operating Lease, Liability, to be Paid, Year One	196
Lessee, Operating Lease, Liability, Payments, Due Year Two	183
Lessee, Operating Lease, Liability, Payments, Due Year Three	140
Lessee, Operating Lease, Liability, Payments, Due Year Four	107
Lessee, Operating Lease, Liability, Payments, Due after Year Five	12
Lessee, Operating Lease, Liability, Payments, Due	786
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	162
Total operating lease liabilities	624	54	771
Operating lease liabilities current liabilities	162	17	151
Operating lease liabilities noncurrent liabilities	462	37	620
Leases Cash Flow [Abstract]
Operating cash flows from operating leases	39	6
Northwest Natural Gas Company [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	72,077	74,361	72,720
Operating lease liabilities current liabilities	1,538	1,286	1,363
Operating lease liabilities noncurrent liabilities	77,840	79,125	78,345
Total operating lease liabilities	79,378	80,411	79,708
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	143,670
Regulatory Assets, Noncurrent	311,394	297,482	340,407
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	5,402
Lessee, Operating Lease, Liability, to be Paid, Year One	7,299
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,185
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,353
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,530
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,901
Lessee, Operating Lease, Liability, Payments, Due	143,670
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	64,292
Total operating lease liabilities	79,378	80,411	79,708
Operating lease liabilities current liabilities	1,538	1,286	1,363
Operating lease liabilities noncurrent liabilities	77,840	79,125	78,345
Leases Cash Flow [Abstract]
Operating cash flows from operating leases	1,767	1,733
Finance Lease, Principal Payments	173	75
Operating leases	0	14
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	173	100
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Leases Cash Flow [Abstract]
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 90	0
New Headquarters Lease [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Term of Contract	20 years
Regulatory Assets, Noncurrent	$ 7,200	$ 6,000	$ 6,900
New Headquarters Lease Renewal Term 2 of 2 [Member] | New Headquarters Lease [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Renewal Term	7 years
New Headquarters Lease Renewal Term 1 of 2 [Member] | New Headquarters Lease [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Renewal Term	7 years
Maximum [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Term of Contract	17 years