Consolidated Statement of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating activities:
Net income	$ 72,915	$ 57,954
Adjustments to reconcile net income to cash provided by operations:
Depreciation	62,758	56,539
Regulatory amortization of gas reserves	1,678	2,984
Deferred income taxes	8,610	10,659
Qualified defined benefit pension plan (benefit) expense	(1,129)	2,882
Deferred environmental expenditures, net	(9,732)	(9,608)
Environmental remediation expense	7,515	6,970
Asset optimization revenue sharing bill credits	(10,471)	(41,102)
Other	14,068	9,961
Changes in assets and liabilities:
Receivables, net	163,965	96,453
Inventories	20,084	(8,721)
Income and other taxes	14,834	17,241
Accounts payable	(48,935)	(13,728)
Deferred gas costs	(16,370)	2,607
Asset optimization revenue sharing	12,056	3,929
Decoupling mechanism	(9,554)	9,669
Change in Cloud-based software Assets	(7,229)	(414)
Other, net	22,791	(7,711)
Cash provided by operating activities	297,854	196,564
Investing activities:
Capital expenditures	(144,863)	(167,696)
Acquisitions, net of cash acquired	(3,249)	0
Payments to Acquire Equity Method Investments	(1,000)	0
Other	(2,428)	(1,991)
Cash used in investing activities	(151,540)	(169,687)
Financing activities:
Proceeds from common stock issued, net	22,072	174,053
Long-term debt issued	200,000	692
Changes in other short-term debt, net	(217,200)	(166,800)
Cash dividend payments on common stock	(33,293)	(30,311)
Other	(3,774)	(1,596)
Cash used in financing activities	(32,195)	(23,962)
Cash, cash equivalents and restricted cash	155,083	30,035
Increase (decrease) in cash, cash equivalents and restricted cash	114,119	2,915
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	36,376	22,867
Income taxes paid, net of refunds	12,163	1,086
Northwest Natural Gas Company [Member]
Operating activities:
Net income	77,324	60,149
Adjustments to reconcile net income to cash provided by operations:
Depreciation	60,024	54,965
Regulatory amortization of gas reserves	1,678	2,984
Deferred income taxes	4,172	10,308
Qualified defined benefit pension plan (benefit) expense	(1,129)	2,882
Deferred environmental expenditures, net	(9,732)	(9,608)
Environmental remediation expense	7,515	6,970
Asset optimization revenue sharing bill credits	(10,471)	(41,102)
Other	13,022	9,158
Changes in assets and liabilities:
Receivables, net	167,936	97,175
Inventories	20,438	(7,974)
Income and other taxes	6,078	16,069
Accounts payable	(52,366)	(16,341)
Deferred gas costs	(16,370)	2,607
Asset optimization revenue sharing	12,056	3,929
Decoupling mechanism	(9,554)	9,669
Change in Cloud-based software Assets	(7,229)	(414)
Other, net	24,613	(7,990)
Cash provided by operating activities	288,005	193,436
Investing activities:
Capital expenditures	(129,298)	(156,189)
Other	(2,428)	(1,991)
Cash used in investing activities	(131,726)	(158,180)
Financing activities:
Capital contributions from parent	0	165,517
Long-term debt issued	200,000	0
Changes in other short-term debt, net	(170,200)	(166,800)
Cash dividend payments on common stock	(58,315)	(30,191)
Other	(3,358)	(1,521)
Cash used in financing activities	(31,873)	(32,995)
Cash, cash equivalents and restricted cash	149,077	23,093
Increase (decrease) in cash, cash equivalents and restricted cash	124,406	2,261
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	28,078	21,270
Income taxes paid, net of refunds	$ 26,745	$ 3,490