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		165,517		165,517
Net income	57,954	60,149			57,954	60,149
Dividends on common stock					(31,770)	(30,191)
Other comprehensive income	58,348	60,543					394	394
Stock-based compensation			2,232
Shares issued pursuant to equity based plans, net of shares withheld for taxes			1,004
Issuances of common stock, net of issuance costs			173,819
Ending Balance at Jun. 30, 2022	$ 1,138,779	1,173,676	767,826	601,032	381,963	583,654	(11,010)	(11,010)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.9650
Beginning 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]
Capital contributions from parent				164,990
Net income	1,715	2,733			1,715	2,733
Dividends on common stock					(16,521)	(15,853)
Other comprehensive income	1,912	2,930					197	197
Stock-based compensation			458
Shares issued pursuant to equity based plans, net of shares withheld for taxes			1,080
Issuances of common stock, net of issuance costs			163,906
Ending Balance at Jun. 30, 2022	$ 1,138,779	1,173,676	767,826	601,032	381,963	583,654	(11,010)	(11,010)
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		0		0
Net income	72,915	77,324			72,915	77,324
Dividends on common stock					(34,990)	(58,315)
Other comprehensive income	73,945	77,529					1,030	205
Stock-based compensation			3,006
Shares issued pursuant to equity based plans, net of shares withheld for taxes			837
Issuances of common stock, net of issuance costs			22,039
Ending Balance at Jun. 30, 2023	$ 1,240,278	1,210,296	831,135	614,903	414,398	601,602	(5,255)	(6,209)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.9700
Beginning 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]
Capital contributions from parent				(8)
Net income	1,244	1,784			1,244	1,784
Dividends on common stock					(17,443)	(41,763)
Other comprehensive income	2,583	1,887					1,339	103
Stock-based compensation			426
Shares issued pursuant to equity based plans, net of shares withheld for taxes			1,011
Issuances of common stock, net of issuance costs			5,394
Ending Balance at Jun. 30, 2023	$ 1,240,278	$ 1,210,296	$ 831,135	$ 614,903	$ 414,398	$ 601,602	$ (5,255)	$ (6,209)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.4850