Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Current assets:
Cash and cash equivalents	$ 20,084	$ 30,168	$ 137,057
Accounts receivable	60,713	88,083	35,196
Accrued unbilled revenue	13,592	57,949	15,393
Allowance for uncollectible accounts	(3,283)	(3,219)	(1,592)
Regulatory assets	60,672	31,745	30,021
Derivative instruments	46,168	13,678	5,996
Inventories	39,024	42,691	44,009
Gas reserves	8,444	11,409	13,646
Income Taxes Receivable, Current	6,000	6,000	0
Other current assets	22,427	44,741	20,318
Discontinued operations current assets	0	0	16,392
Total current assets	273,841	323,245	316,436
Non-current assets:
Property, plant, and equipment	3,849,792	3,734,039	3,608,902
Less: Accumulated depreciation	1,093,863	1,079,269	1,062,299
Property, Plant and Equipment, Net	2,755,929	2,654,770	2,546,603
Gas reserves	29,852	34,484	41,459
Regulatory assets	330,710	348,927	324,358
Derivative instruments	7,912	6,135	3,958
Other investments	47,725	49,259	62,130
Operating lease right of use asset, net	76,294	77,446	78,566
Assets under sales-type leases	141,408	143,759	146,208
Goodwill	69,313	69,225	70,183
Other non-current assets	50,516	49,129	51,446
Total non-current assets	3,509,659	3,433,134	3,324,911
Total assets	3,783,500	3,756,379	3,641,347
Current liabilities:
Short-term debt	240,000	304,525	233,000
Current maturities of long-term debt	60,274	95,344	35,209
Accounts payable	97,854	97,966	79,903
Taxes accrued	15,143	13,812	18,535
Interest accrued	7,425	7,441	7,234
Regulatory liabilities	103,210	50,362	41,126
Derivative instruments	3,393	4,198	3,067
Operating lease liabilities	1,228	1,105	931
Other current liabilities	43,946	52,330	54,323
Discontinued operations current liabilities	0	0	13,574
Total current liabilities	572,473	627,083	486,902
Long-term debt	915,501	860,081	918,887
Deferred credits and other non-current liabilities:
Deferred tax liabilities	325,600	319,292	297,995
Regulatory liabilities	645,046	639,663	632,400
Pension and other postretirement benefit liabilities	203,854	217,287	218,493
Derivative instruments	453	2,852	1,658
Operating lease liabilities	80,088	80,621	80,159
Other non-current liabilities	117,659	120,767	120,852
Total deferred credits and other non-current liabilities	1,372,700	1,380,482	1,351,557
Commitments and contingencies (Note 16)
Equity:
Common stock	$ 569,785	$ 565,112	$ 562,766
Shares Authorized (in shares)	100,000,000	100,000,000	100,000,000
Shares outstanding (in shares)	30,672,000	30,589,000	30,546,000
Shares issued (in shares)	30,672,000	30,589,000	30,546,000
Par Value (in dollars per share)	$ 0	$ 0	$ 0
Retained earnings	$ 365,501	$ 336,523	$ 331,648
Accumulated other comprehensive loss	(12,460)	(12,902)	(10,413)
Total equity	922,826	888,733	884,001
Total liabilities and equity	3,783,500	3,756,379	3,641,347
Northwest Natural Gas Company [Member]
Current assets:
Cash and cash equivalents	11,488	10,453	120,284
Accounts receivable	51,849	80,035	33,985
Accrued unbilled revenue	13,474	57,890	15,236
Receivables from affiliates	301	660	563
Allowance for uncollectible accounts	(3,239)	(3,107)	(1,591)
Regulatory assets	60,672	31,745	30,021
Derivative instruments	46,168	13,678	5,996
Inventories	38,549	42,325	43,619
Gas reserves	8,444	11,409	13,646
Other current assets	22,186	37,909	20,287
Total current assets	249,892	282,997	282,046
Non-current assets:
Property, plant, and equipment	3,794,870	3,683,776	3,564,707
Less: Accumulated depreciation	1,088,743	1,075,446	1,059,760
Property, Plant and Equipment, Net	2,706,127	2,608,330	2,504,947
Gas reserves	29,852	34,484	41,459
Regulatory assets	330,670	348,887	324,320
Derivative instruments	7,912	6,135	3,958
Other investments	47,695	49,242	48,673
Operating lease right of use asset, net	76,211	77,328	78,464
Assets under sales-type leases	141,408	143,759	146,208
Other non-current assets	49,665	48,174	50,629
Total non-current assets	3,389,540	3,316,339	3,198,658
Total assets	3,639,432	3,599,336	3,480,704
Current liabilities:
Short-term debt	198,000	231,525	153,000
Current maturities of long-term debt	59,987	59,955	0
Accounts payable	95,109	95,170	77,993
Payables to affiliates	22,869	13,820	18,450
Taxes accrued	10,072	13,724	7,376
Interest accrued	7,373	7,338	7,156
Regulatory liabilities	103,210	50,362	41,126
Derivative instruments	3,393	4,198	3,067
Operating lease liabilities	1,193	1,054	868
Other current liabilities	43,389	51,907	52,939
Total current liabilities	544,595	529,053	361,975
Long-term debt	857,422	857,265	917,012
Deferred credits and other non-current liabilities:
Deferred tax liabilities	323,522	318,034	309,977
Regulatory liabilities	644,177	638,793	631,531
Pension and other postretirement benefit liabilities	203,854	217,287	218,493
Derivative instruments	453	2,852	1,658
Operating lease liabilities	80,043	80,559	80,120
Other non-current liabilities	116,975	120,309	120,569
Total deferred credits and other non-current liabilities	1,369,024	1,377,834	1,362,348
Equity:
Common stock	319,506	319,506	319,557
Retained earnings	561,345	528,580	530,225
Accumulated other comprehensive loss	(12,460)	(12,902)	(10,413)
Total equity	868,391	835,184	839,369
Total liabilities and equity	$ 3,639,432	$ 3,599,336	$ 3,480,704