Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating revenues [Abstract]
Operating revenues	$ 1,037,353,000	$ 860,400,000	$ 773,679,000
Operating expenses:
Cost of gas	429,635,000	292,314,000	262,755,000
Operations and maintenance	224,667,000	204,227,000	180,129,000
Environmental remediation	12,389,000	9,938,000	9,691,000
General taxes	41,031,000	38,633,000	35,078,000
Revenue taxes	41,826,000	34,740,000	30,291,000
Depreciation	116,707,000	113,534,000	103,683,000
Other operating expenses	3,621,000	3,897,000	3,701,000
Total operating expenses	869,876,000	697,283,000	625,328,000
Income from operations	167,477,000	163,117,000	148,351,000
Other income (expense), net	1,203,000	(12,559,000)	(13,944,000)
Interest expense, net	53,247,000	44,486,000	43,052,000
Income before income taxes	115,433,000	106,072,000	91,355,000
Income tax expense	29,130,000	27,406,000	21,082,000
Net income from continuing operations	86,303,000	78,666,000	70,273,000
Income from discontinued operations, net of tax	0	0	6,508,000
Net income	86,303,000	78,666,000	76,781,000
Other comprehensive income (loss):
Change in employee benefit plan liability, net of taxes	4,195,000	593,000	(2,848,000)
Amortization of non-qualified employee benefit plan liability, net of taxes	795,000	905,000	679,000
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	129,000	0	0
Comprehensive income	91,422,000	80,164,000	74,612,000
Supplemental Income Statement Elements [Abstract]
Change in employee benefit plan liability, taxes	(1,511)	(219)	1,025
Amortization of non-qualified employee benefit plan liability, taxes	(286)	$ (320)	$ (244)
Unrealized Gain on Derivative, tax	$ (47)
Average common shares outstanding:
Basic (in shares)	33,934	30,702	30,541
Diluted (in shares)	33,984	30,752	30,599
Earnings from continuing operations per share of common stock:
Basic (in dollars per share)	$ 2.54	$ 2.56	$ 2.30
Diluted (in dollars per share)	2.54	2.56	2.30
Earnings from discontinued operations per share of common stock, basic
Basic (in dollars per share)	0	0	0.21
Earnings from discontinued operations per share of common stock, diluted
Diluted (in dollars per share)	0	0	0.21
Earnings per share of common stock:
Basic (in dollars per share)	2.54	2.56	2.51
Diluted (in dollars per share)	$ 2.54	$ 2.56	$ 2.51
Northwest Natural Gas Company [Member]
Operating revenues [Abstract]
Operating revenues	$ 1,014,339,000	$ 843,057,000	$ 758,748,000
Operating expenses:
Cost of gas	429,861,000	292,538,000	262,980,000
Utility Operations and maintenance	204,845,000	188,762,000	168,869,000
Environmental remediation	12,389,000	9,938,000	9,691,000
General taxes	40,151,000	38,150,000	34,459,000
Revenue taxes	41,627,000	34,600,000	30,291,000
Depreciation	112,957,000	110,504,000	101,586,000
Other operating expenses	3,135,000	3,332,000	3,232,000
Total operating expenses	844,965,000	677,824,000	611,108,000
Income from operations	169,374,000	165,233,000	147,640,000
Other income (expense), net	(436,000)	(12,745,000)	(15,116,000)
Interest expense, net	46,338,000	42,983,000	40,866,000
Income before income taxes	122,600,000	109,505,000	91,658,000
Income tax expense	31,036,000	28,333,000	21,095,000
Net income	91,564,000	81,172,000	70,563,000
Other comprehensive income (loss):
Change in employee benefit plan liability, net of taxes	4,195,000	593,000	(2,848,000)
Amortization of non-qualified employee benefit plan liability, net of taxes	795,000	905,000	679,000
Comprehensive income	96,554,000	82,670,000	68,394,000
Supplemental Income Statement Elements [Abstract]
Change in employee benefit plan liability, taxes	(1,511)	(219)	1,025
Amortization of non-qualified employee benefit plan liability, taxes	$ (286)	$ (320)	$ (244)