Consolidated Balance Sheets - USD ($) shares in Thousands, $ / shares in Thousands, $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 18,559	$ 30,168
Accounts receivable	101,495	88,083
Accrued unbilled revenue	82,169	57,949
Allowance for uncollectible accounts	(2,018)	(3,219)
Regulatory assets	72,391	31,745
Derivative instruments	48,130	13,678
Inventories	57,262	42,691
Income taxes receivable	0	6,000
Other current assets	59,288	56,150
Total current assets	437,276	323,245
Non-current assets:
Property, plant, and equipment	3,997,243	3,734,039
Less: Accumulated depreciation	1,125,873	1,079,269
Total property, plant, and equipment, net	2,871,370	2,654,770
Regulatory assets	314,579	348,927
Derivative instruments	10,730	6,135
Other investments	89,278	83,743
Operating lease right of use asset	75,049	77,446
Assets under sales-type leases	138,995	143,759
Goodwill	70,570	69,225
Other non-current assets	56,757	49,129
Total non-current assets	3,627,328	3,433,134
Total assets	4,064,604	3,756,379
Current liabilities:
Short-term debt	389,500	304,525
Current maturities of long-term debt	345	95,344
Accounts payable	133,486	97,966
Taxes accrued	15,520	13,812
Interest accrued	7,503	7,441
Regulatory liabilities	112,281	50,362
Derivative instruments	10,402	4,198
Operating lease liabilities	1,296	1,105
Other current liabilities	54,432	52,330
Total current liabilities	724,765	627,083
Long-term debt	1,044,587	860,081
Deferred credits and other non-current liabilities:
Regulatory liabilities	658,332	639,663
Pension and other postretirement benefit liabilities	166,684	217,287
Derivative instruments	412	2,852
Operating lease liabilities	79,468	80,621
Other non-current liabilities	114,979	120,767
Total deferred credits and other non-current liabilities	1,360,106	1,380,482
Commitments and contingencies (see Note 16 and Note 17)
Equity:
Common stock - no par value	590,771	565,112
Retained earnings	355,779	336,523
Accumulated other comprehensive loss	(11,404)	(12,902)
Total equity	935,146	888,733
Total liabilities and equity	$ 4,064,604	$ 3,756,379
Par Value (in dollars per share)	$ 0	$ 0
Shares Authorized (in shares)	100,000	100,000
Shares issued (in shares)	31,129	30,589
Shares outstanding (in shares)	31,129	30,589
Deferred Income Tax Liabilities, Net	$ 340,231	$ 319,292
Northwest Natural Gas Company [Member]
Current assets:
Cash and cash equivalents	12,271	10,453
Accounts receivable	99,780	80,035
Accrued unbilled revenue	82,028	57,890
Receivables from affiliates	261	660
Allowance for uncollectible accounts	(1,962)	(3,107)
Regulatory assets	72,391	31,745
Derivative instruments	48,130	13,678
Inventories	56,752	42,325
Other current assets	47,378	49,318
Total current assets	417,029	282,997
Non-current assets:
Property, plant, and equipment	3,931,640	3,683,776
Less: Accumulated depreciation	1,119,361	1,075,446
Total property, plant, and equipment, net	2,812,279	2,608,330
Regulatory assets	314,539	348,887
Derivative instruments	10,730	6,135
Other investments	74,786	83,726
Operating lease right of use asset	74,987	77,328
Assets under sales-type leases	138,995	143,759
Other non-current assets	55,027	48,174
Total non-current assets	3,481,343	3,316,339
Total assets	3,898,372	3,599,336
Current liabilities:
Short-term debt	245,500	231,525
Current maturities of long-term debt	0	59,955
Accounts payable	131,475	95,170
Payables to affiliates	1,248	13,820
Taxes accrued	15,476	13,724
Interest accrued	7,296	7,338
Regulatory liabilities	112,281	50,362
Derivative instruments	10,402	4,198
Operating lease liabilities	1,273	1,054
Other current liabilities	53,591	51,907
Total current liabilities	578,542	529,053
Long-term debt	986,495	857,265
Deferred credits and other non-current liabilities:
Regulatory liabilities	657,350	638,793
Pension and other postretirement benefit liabilities	166,684	217,287
Derivative instruments	412	2,852
Operating lease liabilities	79,431	80,559
Other non-current liabilities	113,934	120,309
Total deferred credits and other non-current liabilities	1,355,528	1,377,834
Commitments and contingencies (see Note 16 and Note 17)
Equity:
Common stock - no par value	435,515	319,506
Retained earnings	553,696	528,580
Accumulated other comprehensive loss	(11,404)	(12,902)
Total equity	977,807	835,184
Total liabilities and equity	3,898,372	3,599,336
Deferred Income Tax Liabilities, Net	$ 337,717	$ 318,034