Pension and Other Postretirement Benefits Costs - Schedule of Fair Value of Plan Assets - Pension Plan [Member] - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	$ 399,217	$ 373,931
Northwest Natural Gas Company [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	399,217	373,932
Total Pension Asset Investments Net Of Receivables And Payables	399,217	373,931
Accrued interest and dividend income	0	6,429
Total receivables	0	6,429
Due to broker for securities purchased	0	6,429
Northwest Natural Gas Company [Member] | United States Equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	121,090	117,764
Northwest Natural Gas Company [Member] | Non-U.S. equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	123,534	117,206
Northwest Natural Gas Company [Member] | Liability hedging [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	118,464	111,041
Northwest Natural Gas Company [Member] | Opportunistic [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	33,808	25,625
Northwest Natural Gas Company [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	2,321	2,295
Northwest Natural Gas Company [Member] | Level 1 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Total Pension Asset Investments Net Of Receivables And Payables	35,456	39,114
Northwest Natural Gas Company [Member] | Level 1 [Member] | United States Equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 1 [Member] | Non-U.S. equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	35,456	39,114
Northwest Natural Gas Company [Member] | Level 1 [Member] | Liability hedging [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 1 [Member] | Opportunistic [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 1 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Total Pension Asset Investments Net Of Receivables And Payables	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member] | United States Equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member] | Non-U.S. equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member] | Liability hedging [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member] | Opportunistic [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Total Pension Asset Investments Net Of Receivables And Payables	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member] | United States Equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member] | Non-U.S. equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member] | Liability hedging [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member] | Opportunistic [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Total Pension Asset Investments Net Of Receivables And Payables	363,761	334,817
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member] | United States Equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	121,090	117,764
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member] | Non-U.S. equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	88,078	78,092
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member] | Liability hedging [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	118,464	111,041
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member] | Opportunistic [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	33,808	25,625
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	$ 2,321	$ 2,295