Consolidated Statement of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating activities:
Net income	$ 49,228	$ 38,367
Adjustments to reconcile net income to cash provided by operations:
Depreciation	92,819	85,565
Regulatory amortization of gas reserves	2,532	4,527
Deferred income taxes	6,678	7,759
Qualified defined benefit pension plan (benefit) expense	(1,823)	4,013
Deferred environmental expenditures, net	(14,887)	(14,437)
Environmental remediation expense	8,547	7,950
Asset optimization revenue sharing bill credits	(10,471)	(41,102)
Other	18,079	16,640
Changes in assets and liabilities:
Receivables, net	182,297	114,755
Inventories	(6,484)	(41,463)
Income and other taxes	8,770	19,447
Accounts payable	(39,695)	(30,010)
Deferred gas costs	(8,678)	(1,785)
Asset optimization revenue sharing	18,667	17,629
Decoupling mechanism	(12,328)	7,124
Change in Cloud-based software Assets	(12,316)	(17,332)
Other, net	20,568	(11,686)
Cash provided by operating activities	301,503	165,961
Investing activities:
Capital expenditures	(242,747)	(251,842)
Acquisitions, net of cash acquired	(3,248)	(2,352)
Other	(4,525)	(2,810)
Cash used in investing activities	(250,520)	(257,004)
Financing activities:
Proceeds from common stock issued, net	40,955	190,929
Long-term debt issued	330,000	290,000
Long-term debt retired	(50,000)	0
Changes in other short-term debt, net	(187,200)	(248,500)
Cash dividend payments on common stock	(50,114)	(46,434)
Other	(4,108)	(1,802)
Cash used in financing activities	79,533	184,193
Cash, cash equivalents and restricted cash	171,480	120,270
Increase (decrease) in cash, cash equivalents and restricted cash	130,516	93,150
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	51,970	31,774
Income taxes paid, net of refunds	18,963	2,106
Northwest Natural Gas Company [Member]
Operating activities:
Net income	55,837	41,343
Adjustments to reconcile net income to cash provided by operations:
Depreciation	88,470	83,166
Regulatory amortization of gas reserves	2,532	4,527
Deferred income taxes	1,411	7,013
Qualified defined benefit pension plan (benefit) expense	(1,823)	4,013
Deferred environmental expenditures, net	(14,887)	(14,437)
Environmental remediation expense	8,547	7,950
Asset optimization revenue sharing bill credits	(10,471)	(41,102)
Other	17,331	16,665
Changes in assets and liabilities:
Receivables, net	183,116	115,915
Inventories	(6,173)	(40,881)
Income and other taxes	6,942	17,412
Accounts payable	(43,315)	(32,023)
Deferred gas costs	(8,678)	(1,785)
Asset optimization revenue sharing	18,667	17,629
Decoupling mechanism	(12,328)	7,124
Change in Cloud-based software Assets	(12,316)	(17,332)
Other, net	21,306	(12,604)
Cash provided by operating activities	294,168	162,593
Investing activities:
Capital expenditures	(216,368)	(236,467)
Other	(3,524)	(2,810)
Cash used in investing activities	(219,892)	(239,277)
Financing activities:
Capital contributions from parent	30,000	179,388
Long-term debt issued	330,000	140,000
Long-term debt retired	(50,000)	0
Changes in other short-term debt, net	(170,200)	(192,500)
Cash dividend payments on common stock	(75,123)	(46,319)
Other	(3,713)	(1,617)
Cash used in financing activities	60,964	78,952
Cash, cash equivalents and restricted cash	159,911	23,100
Increase (decrease) in cash, cash equivalents and restricted cash	135,240	2,268
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	39,911	28,326
Income taxes paid, net of refunds	$ 27,745	$ 5,990