Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Current assets:
Cash and cash equivalents	$ 35,047	$ 32,920	$ 156,616
Accounts receivable	53,123	121,341	51,999
Accrued unbilled revenue	23,818	83,138	24,626
Allowance for uncollectible accounts	(2,885)	(3,455)	(2,312)
Regulatory assets	136,275	178,270	108,525
Derivative instruments	8,948	11,380	23,454
Inventories	108,651	112,571	94,585
Other current assets	45,873	65,275	49,947
Total current assets	408,850	601,440	507,440
Non-current assets:
Property, plant, and equipment	4,858,066	4,556,609	4,468,602
Less: Accumulated depreciation	1,245,725	1,198,555	1,189,968
Total property, plant, and equipment, net	3,612,341	3,358,054	3,278,634
Regulatory assets	322,781	333,443	312,665
Derivative instruments	1,377	431	6,188
Other investments	82,478	102,951	104,562
Operating lease right of use asset, net	69,402	71,308	71,477
Assets under sales-type leases	126,712	129,882	130,952
Goodwill	181,393	163,344	152,399
Other non-current assets	139,035	106,239	100,801
Total non-current assets	4,535,519	4,265,652	4,157,678
Total assets	4,944,369	4,867,092	4,665,118
Current liabilities:
Short-term debt	159,814	89,780	71,000
Current maturities of long-term debt	20,796	150,865	190,728
Accounts payable	96,260	145,361	99,326
Taxes accrued	17,759	15,454	17,120
Interest accrued	12,909	15,836	13,940
Regulatory liabilities	127,640	84,962	88,376
Derivative instruments	70,807	98,661	46,603
Operating lease liabilities	1,868	2,333	1,815
Other current liabilities	59,532	93,626	61,149
Total current liabilities	567,385	696,878	590,057
Long-term debt	1,555,000	1,425,435	1,424,572
Deferred credits and other non-current liabilities:
Deferred tax liabilities	389,281	382,673	375,917
Regulatory liabilities	708,948	695,896	683,262
Pension and other postretirement benefit liabilities	138,800	158,116	145,991
Derivative instruments	15,714	28,055	21,085
Operating lease liabilities	76,530	77,167	77,475
Other non-current liabilities	135,661	119,034	127,219
Total deferred credits and other non-current liabilities	1,464,934	1,460,941	1,430,949
Commitments and contingencies (Note 16)
Equity:
Common stock	$ 986,545	$ 890,976	$ 851,288
Shares Authorized (in shares)	100,000,000	100,000,000	100,000,000
Shares outstanding (in shares)	40,120,524	37,631,212	36,575,797
Shares issued (in shares)	40,120,524	37,631,212	36,575,797
Par Value (in dollars per share)	$ 0	$ 0	$ 0
Retained earnings	$ 377,685	$ 399,911	$ 373,231
Accumulated other comprehensive loss	(7,180)	(7,049)	(4,979)
Total equity	1,357,050	1,283,838	1,219,540
Total liabilities and equity	4,944,369	4,867,092	4,665,118
Northwest Natural Gas Company [Member]
Current assets:
Cash and cash equivalents	18,268	19,841	145,073
Accounts receivable	47,094	117,216	48,322
Accrued unbilled revenue	21,548	81,524	22,608
Other Receivables, Net, Current	3,888	824	2,195
Allowance for uncollectible accounts	(2,534)	(3,228)	(2,085)
Regulatory assets	136,250	178,270	108,525
Derivative instruments	9,093	11,184	22,679
Inventories	106,824	110,855	92,803
Other current assets	32,363	60,138	38,131
Total current assets	372,794	576,624	478,251
Non-current assets:
Property, plant, and equipment	4,654,081	4,393,759	4,328,477
Less: Accumulated depreciation	1,222,218	1,181,962	1,175,283
Total property, plant, and equipment, net	3,431,863	3,211,797	3,153,194
Regulatory assets	322,124	333,418	312,640
Derivative instruments	1,481	373	5,430
Other investments	64,313	86,145	87,753
Operating lease right of use asset, net	68,846	70,728	70,852
Assets under sales-type leases	126,712	129,882	130,952
Other non-current assets	110,352	102,410	99,131
Total non-current assets	4,125,691	3,934,753	3,859,952
Total assets	4,498,485	4,511,377	4,338,203
Current liabilities:
Short-term debt	100,114	16,780	0
Current maturities of long-term debt	19,993	0	39,997
Accounts payable	87,703	138,111	94,922
Accounts Payable, Other, Current	464	14,850	562
Taxes accrued	17,186	15,293	16,915
Interest accrued	12,049	15,111	13,368
Regulatory liabilities	127,508	84,912	88,326
Derivative instruments	70,807	98,661	46,603
Operating lease liabilities	1,627	2,128	1,658
Other current liabilities	56,551	89,371	59,101
Total current liabilities	494,002	475,217	361,452
Long-term debt	1,345,240	1,364,732	1,364,556
Deferred credits and other non-current liabilities:
Deferred tax liabilities	376,321	371,867	366,730
Regulatory liabilities	708,003	694,947	682,315
Pension and other postretirement benefit liabilities	138,800	158,116	145,991
Derivative instruments	15,714	28,055	21,085
Operating lease liabilities	76,217	76,757	77,041
Other non-current liabilities	124,302	109,066	116,930
Total deferred credits and other non-current liabilities	1,439,357	1,438,808	1,410,092
Commitments and contingencies (Note 16)
Equity:
Common stock	644,903	644,903	644,903
Retained earnings	581,980	594,954	563,307
Accumulated other comprehensive loss	(6,997)	(7,237)	(6,107)
Total equity	1,219,886	1,232,620	1,202,103
Total liabilities and equity	$ 4,498,485	$ 4,511,377	$ 4,338,203
Other Receivable, after Allowance for Credit Loss, Related Party [Extensible Enumeration]	Affiliated Entity [Member]	Affiliated Entity [Member]	Affiliated Entity [Member]
Accounts Payable, Related Party [Extensible Enumeration]	Affiliated Entity [Member]	Affiliated Entity [Member]	Affiliated Entity [Member]