Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating revenues [Abstract]
Operating revenues	$ 141,479,000	$ 116,839,000	$ 841,761,000	$ 662,100,000
Operating expenses:
Cost of gas	49,180,000	36,105,000	357,362,000	261,413,000
Operations and maintenance	61,524,000	50,745,000	200,160,000	161,405,000
Environmental remediation	1,032,000	980,000	8,547,000	7,950,000
General taxes	10,577,000	9,572,000	35,685,000	30,665,000
Revenue taxes	5,523,000	4,437,000	33,750,000	26,037,000
Depreciation	30,061,000	29,026,000	92,819,000	85,565,000
Other operating expenses	1,159,000	901,000	3,664,000	2,815,000
Total operating expenses	159,056,000	131,766,000	731,987,000	575,850,000
Income from operations	(17,577,000)	(14,927,000)	109,774,000	86,250,000
Other income (expense), net	5,004,000	1,636,000	13,228,000	908,000
Interest expense, net	19,406,000	13,054,000	56,676,000	36,156,000
Income (loss) before income taxes	(31,979,000)	(26,345,000)	66,326,000	51,002,000
Income tax expense (benefit)	(8,292,000)	(6,758,000)	17,098,000	12,635,000
Net income (loss)	(23,687,000)	(19,587,000)	49,228,000	38,367,000
Other comprehensive income (loss):
Amortization of non-qualified employee benefit plan liability, net of taxes	102,000	202,000	307,000	596,000
Derivative, Gain (Loss) on Derivative, Net	174,000	0	999,000	0
Comprehensive income (loss)	(23,411,000)	(19,385,000)	50,534,000	38,963,000
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	37,000	$ 73,000	111,000	$ 215,000
Unrealized Loss on Derivative, tax	$ (62)		$ (359)
Average common shares outstanding:
Basic (in shares)	36,214	34,939	35,950	33,491
Diluted (in shares)	36,214	34,939	35,980	33,539
Earnings per share of common stock:
Basic (in dollars per share)	$ (0.65)	$ (0.56)	$ 1.37	$ 1.15
Diluted (in dollars per share)	$ (0.65)	$ (0.56)	$ 1.37	$ 1.14
Northwest Natural Gas Company [Member]
Operating revenues [Abstract]
Operating revenues	$ 129,942,000	$ 110,426,000	$ 812,803,000	$ 647,301,000
Operating expenses:
Cost of gas	49,235,000	36,164,000	357,530,000	261,584,000
Operations and maintenance	53,494,000	45,858,000	179,121,000	148,614,000
Environmental remediation	1,032,000	980,000	8,547,000	7,950,000
General taxes	10,328,000	9,467,000	34,925,000	30,328,000
Revenue taxes	5,425,000	4,375,000	33,559,000	25,907,000
Depreciation	28,446,000	28,201,000	88,470,000	83,166,000
Other operating expenses	397,000	675,000	1,636,000	2,370,000
Total operating expenses	148,357,000	125,720,000	703,788,000	559,919,000
Income from operations	(18,415,000)	(15,294,000)	109,015,000	87,382,000
Other income (expense), net	4,818,000	1,161,000	11,095,000	197,000
Interest expense, net	15,597,000	11,128,000	45,236,000	32,558,000
Income (loss) before income taxes	(29,194,000)	(25,261,000)	74,874,000	55,021,000
Income tax expense (benefit)	(7,707,000)	(6,455,000)	19,037,000	13,678,000
Net income (loss)	(21,487,000)	(18,806,000)	55,837,000	41,343,000
Other comprehensive income (loss):
Amortization of non-qualified employee benefit plan liability, net of taxes	102,000	202,000	307,000	596,000
Comprehensive income (loss)	(21,385,000)	(18,604,000)	56,144,000	41,939,000
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	$ 37,000	$ 73,000	$ 111,000	$ 215,000