Significant Accounting Policies - Regulatory Liability Disclosure - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	$ 97,277	$ 112,281	$ 103,210
Regulatory Liability, Noncurrent	658,925	658,332	645,046
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	982	982	869
Northwest Natural Gas Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	97,277	112,281	103,210
Regulatory Liability, Noncurrent	657,943	657,350	644,177
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	1,898	70	1,519
Regulatory Liability, Noncurrent	353	250	101
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	60,652	48,130	46,168
Regulatory Liability, Noncurrent	9,121	10,730	7,912
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	14,242	4,475	5,821
Regulatory Liability, Noncurrent	2,557	3,412	652
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	7,318	8,192	8,217
Regulatory Liability, Noncurrent	176,358	181,404	182,977
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	3,406	6,290	2,137
Regulatory Liability, Noncurrent	13,760	13,792	12,850
Northwest Natural Gas Company [Member] | Accrued asset removal costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	455,794	445,952	439,685
Northwest Natural Gas Company [Member] | Asset Optimization Revenue Sharing
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	9,761	45,124	39,348
Regulatory Liability, Noncurrent	$ 0	$ 1,810	$ 0