Debt Fair Value of Long Term Debt - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Debt Instrument [Line Items]
Gross long-term debt	$ 1,053,912	$ 1,053,241	$ 983,221
Unamortized debt issuance costs	(8,031)	(8,309)	(7,446)
Carrying amount	1,045,881	1,044,932	975,775
Estimated fair value	950,597	1,174,500	1,104,230
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Gross long-term debt	994,700	994,700	924,700
Unamortized debt issuance costs	(7,938)	(8,205)	(7,291)
Carrying amount	986,762	986,495	917,409
Estimated fair value	$ 891,064	$ 1,110,741	$ 1,043,696