Pension and Other Postretirement Benefits Costs - Schedule of Components of Net Periodic Benefit Cost for NW Natural (Details) - Northwest Natural Gas Company Consolidated [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 193	$ 238	$ 258
Interest cost	724	684	905
Expected return on plan assets	0	0	0
Amortization of prior service credit	(333)	(468)	(468)
Amortization of net actuarial loss	(426)	(645)	(607)
Net periodic benefit cost	1,010	1,099	1,302
Amount allocated to construction	76	93	98
Net periodic benefit cost charged to expense	934	1,006	1,204
Amortization of Regulatory Balancing Account	0	0	0
Defined Benefit Plan Net Amount Charged To Expense	934	1,006	1,204
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5,933	6,981	6,614
Interest cost	14,593	13,448	16,161
Expected return on plan assets	25,698	24,232	21,865
Amortization of prior service credit	0	0	0
Amortization of net actuarial loss	(12,612)	(22,475)	(19,550)
Net periodic benefit cost	7,440	18,672	20,460
Amount allocated to construction	2,621	3,015	2,798
Net periodic benefit cost charged to expense	4,819	15,657	17,662
Amortization of Regulatory Balancing Account	7,131	7,131	7,131
Defined Benefit Plan Net Amount Charged To Expense	11,950	$ 22,788	$ 24,793
Operating Expense [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory Pension Disallowance	2,600
Other Nonoperating Income (Expense) [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory Pension Disallowance	$ 4,500