Debt Fair Value of Long Term Debt - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Debt Instrument [Line Items]
Gross long-term debt	$ 1,545,553	$ 1,345,851	$ 1,053,912
Unamortized debt issuance costs	(10,261)	(8,987)	(8,031)
Long-term Debt	1,535,292	1,336,864	1,045,881
Estimated fair value	1,385,612	1,148,395	950,597
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Gross long-term debt	1,334,700	1,134,700	994,700
Unamortized debt issuance costs	(10,141)	(8,823)	(7,938)
Long-term Debt	1,324,559	1,125,877	986,762
Estimated fair value	$ 1,176,519	$ 944,383	$ 891,064