Leases - Lease Asset and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating Lease Asset and Liabilities [Abstract]
Operating Lease, Right-of-Use Asset	$ 75,049	$ 77,446
Operating Lease, Liability, Current	1,296	1,105
Operating Lease, Liability, Noncurrent	79,468	80,621
Operating Lease, Liability	$ 80,764	$ 81,726
Operating Lease, Weighted Average Remaining Lease Term	18 years 2 months 12 days	19 years 2 months 12 days
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 6,992
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,019
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,156
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,191
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,359
Lessee, Operating Lease, Liability, Payments, Due after Year Five	116,449
Lessee, Operating Lease, Liability, Payments, Due	152,166
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	71,402
Operating Lease, Liability	80,764	$ 81,726
Operating Lease, Liability, Current	1,296	1,105
Operating Lease, Liability, Noncurrent	79,468	80,621
Lease Not Yet Commenced [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	152,166
Leases Cash Flow [Abstract]
Operating Lease, Payments	6,898	4,597
Finance Lease, Principal Payments	801	835
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	223	78,590
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	314	1,386
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	6,992
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,019
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,156
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,191
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,359
Lessee, Operating Lease, Liability, Payments, Due after Year Five	116,449
Lessee, Operating Lease, Liability, Payments, Due	152,166
Regulatory Assets, Noncurrent	314,579	348,927
Finance Lease, Liability, to be Paid, Year One	300
Property, Plant and Equipment
Finance Leases [Abstract]
Finance Lease, Right-of-Use Asset	2,100	1,800
Northwest Natural Gas Company [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating Lease, Right-of-Use Asset	74,987	77,328
Operating Lease, Liability, Current	1,273	1,054
Operating Lease, Liability, Noncurrent	79,431	80,559
Operating Lease, Liability	$ 80,704	$ 81,613
Operating Lease, Weighted Average Discount Rate, Percent	7.20%	7.20%
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 6,968
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,013
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,150
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,185
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,353
Lessee, Operating Lease, Liability, Payments, Due after Year Five	116,431
Lessee, Operating Lease, Liability, Payments, Due	152,100
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	71,396
Operating Lease, Liability	80,704	$ 81,613
Operating Lease, Liability, Current	1,273	1,054
Operating Lease, Liability, Noncurrent	79,431	80,559
Lease Not Yet Commenced [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	152,100
Leases Cash Flow [Abstract]
Operating Lease, Payments	6,840	4,466
Finance Lease, Principal Payments	801	835
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	223	78,539
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	314	1,386
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	6,968
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,013
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,150
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,185
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,353
Lessee, Operating Lease, Liability, Payments, Due after Year Five	116,431
Lessee, Operating Lease, Liability, Payments, Due	152,100
Regulatory Assets, Noncurrent	314,539	348,887
Corporate, Non-Segment [Member] | Northwest Holdings Other [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating Lease, Right-of-Use Asset	62	118
Operating Lease, Liability, Current	23	51
Operating Lease, Liability, Noncurrent	37	62
Operating Lease, Liability	60	113
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	24
Lessee, Operating Lease, Liability, Payments, Due Year Two	6
Lessee, Operating Lease, Liability, Payments, Due Year Three	6
Lessee, Operating Lease, Liability, Payments, Due Year Four	6
Lessee, Operating Lease, Liability, Payments, Due Year Five	6
Lessee, Operating Lease, Liability, Payments, Due after Year Five	18
Lessee, Operating Lease, Liability, Payments, Due	66
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	6
Operating Lease, Liability	60	113
Operating Lease, Liability, Current	23	51
Operating Lease, Liability, Noncurrent	37	62
Lease Not Yet Commenced [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	66
Leases Cash Flow [Abstract]
Operating Lease, Payments	58	131
Finance Lease, Principal Payments	0	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	0	51
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	0	$ 0
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	24
Lessee, Operating Lease, Liability, Payments, Due Year Two	6
Lessee, Operating Lease, Liability, Payments, Due Year Three	6
Lessee, Operating Lease, Liability, Payments, Due Year Four	6
Lessee, Operating Lease, Liability, Payments, Due Year Five	6
Lessee, Operating Lease, Liability, Payments, Due after Year Five	18
Lessee, Operating Lease, Liability, Payments, Due	$ 66
Maximum [Member]
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Term of Contract	18 years