Significant Accounting Policies Significant Accounting Policies - Leases ASU 2016-02 (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 71,308	$ 73,429
Northwest Natural Gas Company [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 70,728	$ 72,720