Debt Fair Value of Long Term Debt - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Debt Instrument [Line Items]
Gross long-term debt	$ 1,545,730	$ 1,345,851	$ 1,053,177
Unamortized debt issuance costs	(10,428)	(8,987)	(8,171)
Long-term Debt	1,535,302	1,336,864	1,045,006
Estimated fair value	1,395,321	1,148,395	1,059,629
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	(10,278)	(8,823)	(8,073)
Long-term Debt	1,324,422	1,125,877	986,627
Estimated fair value	$ 1,186,110	$ 944,383	$ 997,196