Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Operating revenues [Abstract]
Operating revenues	$ 116,839	$ 101,447	$ 662,100	$ 566,310
Operating expenses:
Cost of gas	36,105	25,266	261,413	178,669
Operations and maintenance	50,745	47,329	161,405	149,567
Environmental remediation	980	806	7,950	6,092
General taxes	9,572	9,061	30,665	29,344
Revenue taxes	4,437	3,891	26,037	22,226
Depreciation	29,026	28,438	85,565	84,679
Other operating expenses	901	1,047	2,815	2,794
Total operating expenses	131,766	115,838	575,850	473,371
Income from operations	(14,927)	(14,391)	86,250	92,939
Other income (expense), net	1,636	(2,216)	908	(8,355)
Interest expense, net	13,054	11,175	36,156	33,329
Income (loss) before income taxes	(26,345)	(27,782)	51,002	51,255
Income tax expense (benefit)	(6,758)	(7,127)	12,635	13,117
Net income (loss)	(19,587)	(20,655)	38,367	38,138
Other comprehensive income (loss):
Amortization of non-qualified employee benefit plan liability, net of taxes	202	234	596	676
Comprehensive income (loss)	(19,385)	(20,421)	38,963	38,814
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	$ 73	$ 80	$ 215	$ 240
Average common shares outstanding:
Basic (in shares)	34,939	30,696	33,491	30,659
Diluted (in shares)	34,939	30,696	33,539	30,708
Earnings per share of common stock:
Basic (in dollars per share)	$ (0.56)	$ (0.67)	$ 1.15	$ 1.24
Diluted (in dollars per share)	$ (0.56)	$ (0.67)	$ 1.14	$ 1.24
Northwest Natural Gas Company [Member]
Operating revenues [Abstract]
Operating revenues	$ 110,426	$ 96,036	$ 647,301	$ 552,965
Operating expenses:
Cost of gas	36,164	25,322	261,584	178,837
Operations and maintenance	45,858	43,768	148,614	137,894
Environmental remediation	980	806	7,950	6,092
General taxes	9,467	8,999	30,328	29,041
Revenue taxes	4,375	3,838	25,907	22,143
Depreciation	28,201	27,719	83,166	82,418
Other operating expenses	675	669	2,370	2,368
Total operating expenses	125,720	111,121	559,919	458,793
Income from operations	(15,294)	(15,085)	87,382	94,172
Other income (expense), net	1,161	(2,295)	197	(8,526)
Interest expense, net	11,128	10,850	32,558	32,336
Income (loss) before income taxes	(25,261)	(28,230)	55,021	53,310
Income tax expense (benefit)	(6,455)	(7,212)	13,678	13,628
Net income (loss)	(18,806)	(21,018)	41,343	39,682
Other comprehensive income (loss):
Amortization of non-qualified employee benefit plan liability, net of taxes	202	234	596	676
Comprehensive income (loss)	(18,604)	(20,784)	41,939	40,358
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	$ 73	$ 80	$ 215	$ 240