Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Operating revenues [Abstract]
Operating revenues	$ 237,859,000	$ 194,960,000	$ 700,282,000	$ 545,261,000
Operating expenses:
Cost of gas	102,433,000	79,720,000	308,182,000	225,308,000
Operations and maintenance	66,819,000	53,175,000	138,636,000	110,660,000
Environmental remediation	2,140,000	2,267,000	7,515,000	6,970,000
General taxes	10,889,000	8,989,000	25,108,000	21,093,000
Revenue taxes	9,185,000	8,240,000	28,227,000	21,600,000
Depreciation	31,293,000	28,110,000	62,758,000	56,539,000
Other operating expenses	1,257,000	920,000	2,505,000	1,914,000
Total operating expenses	224,016,000	181,421,000	572,931,000	444,084,000
Income from operations	13,843,000	13,539,000	127,351,000	101,177,000
Other income (expense), net	6,618,000	226,000	8,224,000	(728,000)
Interest expense, net	18,974,000	11,580,000	37,270,000	23,102,000
Income (loss) before income taxes	1,487,000	2,185,000	98,305,000	77,347,000
Income tax expense	243,000	470,000	25,390,000	19,393,000
Net income	1,244,000	1,715,000	72,915,000	57,954,000
Other comprehensive income:
Amortization of non-qualified employee benefit plan liability, net of taxes	103,000	197,000	205,000	394,000
Derivative, Gain (Loss) on Derivative, Net	1,236,000		825,000	0
Comprehensive income	2,583,000	1,912,000	73,945,000	58,348,000
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	37,000	$ 71,000	74,000	$ 142,000
Unrealized Loss on Derivative, tax	$ (445)		$ (297)
Average common shares outstanding:
Basic (in shares)	36,019	34,307	35,815	32,756
Diluted (in shares)	36,062	34,352	35,845	32,805
Earnings per share of common stock:
Basic (in dollars per share)	$ 0.03	$ 0.05	$ 2.04	$ 1.77
Diluted (in dollars per share)	$ 0.03	$ 0.05	$ 2.03	$ 1.77
Northwest Natural Gas Company [Member]
Operating revenues [Abstract]
Operating revenues	$ 228,348,000	$ 190,251,000	$ 682,861,000	$ 536,875,000
Operating expenses:
Cost of gas	102,490,000	79,776,000	308,295,000	225,420,000
Operations and maintenance	60,238,000	48,879,000	125,627,000	102,756,000
Environmental remediation	2,140,000	2,267,000	7,515,000	6,970,000
General taxes	10,597,000	8,872,000	24,597,000	20,861,000
Revenue taxes	9,159,000	8,208,000	28,134,000	21,532,000
Depreciation	29,880,000	27,328,000	60,024,000	54,965,000
Other operating expenses	542,000	796,000	1,239,000	1,695,000
Total operating expenses	215,046,000	176,126,000	555,431,000	434,199,000
Income from operations	13,302,000	14,125,000	127,430,000	102,676,000
Other income (expense), net	3,832,000	17,000	6,277,000	(964,000)
Interest expense, net	15,028,000	10,599,000	29,639,000	21,430,000
Income (loss) before income taxes	2,106,000	3,543,000	104,068,000	80,282,000
Income tax expense	322,000	810,000	26,744,000	20,133,000
Net income	1,784,000	2,733,000	77,324,000	60,149,000
Other comprehensive income:
Amortization of non-qualified employee benefit plan liability, net of taxes	103,000	197,000	205,000	394,000
Comprehensive income	1,887,000	2,930,000	77,529,000	60,543,000
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	$ 37,000	$ 71,000	$ 74,000	$ 142,000