Significant Accounting Policies - Regulatory Liability Disclosure (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	$ 248,582	$ 112,281
Regulatory Liability, Noncurrent	689,578	658,332
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	29	0
Regulatory Liability, Noncurrent	979	982
Northwest Natural Gas Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	248,553	112,281
Regulatory Liability, Noncurrent	688,599	657,350
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	4,121	70
Regulatory Liability, Noncurrent	12,644	250
Northwest Natural Gas Company [Member] | Unrealized gain on derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	194,236	48,130
Regulatory Liability, Noncurrent	5,045	10,730
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	14,026	4,475
Regulatory Liability, Noncurrent	3,814	3,412
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	2,636	6,290
Regulatory Liability, Noncurrent	16,741	13,792
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	7,166	8,192
Regulatory Liability, Noncurrent	174,212	181,404
Northwest Natural Gas Company [Member] | Accrued asset removal costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	467,742	445,952
Northwest Natural Gas Company [Member] | Asset Optimization Revenue Sharing
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	26,368	45,124
Regulatory Liability, Noncurrent	$ 8,401	$ 1,810