Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating revenues [Abstract]
Operating revenues	$ 462,423,000	$ 350,301,000
Operating expenses:
Cost of gas	205,749,000	145,588,000
Operations and maintenance	71,817,000	57,485,000
Environmental remediation	5,375,000	4,703,000
General taxes	14,219,000	12,104,000
Revenue taxes	19,042,000	13,360,000
Depreciation	31,465,000	28,429,000
Other operating expenses	1,248,000	994,000
Total operating expenses	348,915,000	262,663,000
Income from operations	113,508,000	87,638,000
Other income (expense), net	1,606,000	(954,000)
Interest expense, net	18,296,000	11,522,000
Income (loss) before income taxes	96,818,000	75,162,000
Income tax expense	25,147,000	18,923,000
Net income	71,671,000	56,239,000
Other comprehensive income (loss):
Amortization of non-qualified employee benefit plan liability, net of taxes	102,000	197,000
Derivative, Gain (Loss) on Derivative, Net	(411,000)	0
Comprehensive income	71,362,000	56,436,000
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	37,000	$ 71,000
Unrealized Loss on Derivative, tax	$ (149)
Average common shares outstanding:
Basic (in shares)	35,609	31,187
Diluted (in shares)	35,708	31,212
Earnings per share of common stock:
Basic (in dollars per share)	$ 2.01	$ 1.80
Diluted (in dollars per share)	$ 2.01	$ 1.80
Northwest Natural Gas Company [Member]
Operating revenues [Abstract]
Operating revenues	$ 454,513,000	$ 346,624,000
Operating expenses:
Cost of gas	205,805,000	145,644,000
Operations and maintenance	65,389,000	53,877,000
Environmental remediation	5,375,000	4,703,000
General taxes	14,000,000	11,989,000
Revenue taxes	18,975,000	13,324,000
Depreciation	30,144,000	27,637,000
Other operating expenses	697,000	899,000
Total operating expenses	340,385,000	258,073,000
Income from operations	114,128,000	88,551,000
Other income (expense), net	2,445,000	(981,000)
Interest expense, net	14,611,000	10,831,000
Income (loss) before income taxes	101,962,000	76,739,000
Income tax expense	26,422,000	19,323,000
Net income	75,540,000	57,416,000
Other comprehensive income (loss):
Amortization of non-qualified employee benefit plan liability, net of taxes	102,000	197,000
Comprehensive income	75,642,000	57,613,000
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	$ 37,000	$ 71,000