Contingent Liabilities and Commitments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Site Contingency [Line Items]
Other	$ 16,282	$ 10,588
Regulatory assets	2,111	2,054
Environmental assessment and remediation [Member]
Site Contingency [Line Items]
Accrued environmental assessment and remediation costs, total	$ 1,000	$ 1,000
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]	Other, Other Liabilities, Noncurrent	Other, Other Liabilities, Noncurrent
Accrued environmental assessment and remediation costs, current	$ 200	$ 200
Environmental Loss Contingency, Current, Statement of Financial Position [Extensible Enumeration]	Other	Other
Accrued environmental assessment and remediation costs, noncurrent	$ 800	$ 800
Environmental Loss Contingency, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Washington State Climate Commitment Act [Member]
Site Contingency [Line Items]
Other	$ 1,700	$ 3,700
Regulatory assets	23,700	$ 22,300
Interest Income, Other	$ 400