Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Total	Northwest Natural Gas Company [Member]	Common Stock Including APIC [Member]	Common Stock Including APIC [Member] Northwest Natural Gas Company [Member]	Retained Earnings [Member]	Retained Earnings [Member] Northwest Natural Gas Company [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Northwest Natural Gas Company [Member]
Beginning Balance at Dec. 31, 2021	$ 935,146	$ 977,807	$ 590,771	$ 435,515	$ 355,779	$ 553,696	$ (11,404)	$ (11,404)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital contributions from parent		527		527
Net income	56,239	57,416			56,239	57,416
Dividends on common stock					(15,249)	(14,338)
Other comprehensive income (loss)	56,436	57,613					197	197
Stock-based compensation			1,774
Shares issued pursuant to equity based plans, net of shares withheld for taxes			(76)
Issuances of common stock, net of issuance costs			9,913
Ending Balance at Mar. 31, 2022	$ 987,944	1,021,609	602,382	436,042	396,769	596,774	(11,207)	(11,207)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.4825
Beginning Balance at Dec. 31, 2022	$ 1,175,441	1,191,082	805,253	614,903	376,473	582,593	(6,285)	(6,414)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital contributions from parent		8		8
Net income	71,671	75,540			71,671	75,540
Dividends on common stock					(17,547)	(16,552)
Other comprehensive income (loss)	71,362	75,642					(309)	102
Stock-based compensation			2,580
Shares issued pursuant to equity based plans, net of shares withheld for taxes			(174)
Issuances of common stock, net of issuance costs			16,645
Ending Balance at Mar. 31, 2023	$ 1,248,307	$ 1,250,180	$ 824,304	$ 614,911	$ 430,597	$ 641,581	$ (6,594)	$ (6,312)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.4850