Supplemental Cash Flow - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 20,084	$ 30,168	$ 137,057
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	28,310	35,454	142,548	$ 12,636
Northwest Natural Gas Company [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	11,488	10,453	120,284
Restricted Cash	8,226	5,286	5,491
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	19,714	15,739	125,775	$ 8,907
Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash	$ 8,226	$ 5,286	$ 5,491