Consolidated Statement of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating activities:
Net income	$ 24,734	$ 24,995
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	76,445	67,334
Regulatory amortization of gas reserves	13,711	14,474
Deferred income taxes	(390)	2,471
Qualified defined benefit pension plan expense	13,800	10,464
Contributions to qualified defined benefit pension plans	(23,670)	(7,810)
Deferred environmental expenditures, net	(16,469)	(10,992)
Amortization of environmental remediation	6,494	7,258
Regulatory revenue recovery deferral from the TCJA	0	742
Regulatory disallowance of pension costs	0	10,500
Other	(4,483)	9,058
Changes in assets and liabilities:
Receivables, net	77,236	80,205
Inventories	(1,126)	(3,293)
Income and other taxes	12,038	21,510
Accounts payable	(20,311)	(31,767)
Interest accrued	2,194	3,100
Deferred gas costs	(2,472)	(47,085)
Decoupling mechanism	4,175	11,095
Other, net	(14,072)	(6,713)
Discontinued operations	706	(255)
Cash provided by operating activities	148,540	155,291
Investing activities:
Capital expenditures	(193,336)	(152,993)
Acquisitions, net of cash acquired	(38,078)	(56,189)
Leasehold improvement expenditures	(7,827)	(13,027)
Proceeds from the sale of assets	8,003	281
Proceeds from Sale of Equity Method Investments	7,000	0
Other	(240)	(2,714)
Discontinued operations	(2,287)	(648)
Cash used in investing activities	(226,765)	(225,290)
Financing activities:
Proceeds from stock options exercised	68	1,723
Proceeds from common stock issued	0	93,182
Long-term debt issued	150,000	175,000
Long-term debt retired	(75,000)	(10,000)
Proceeds from term loan due within one year	150,000	0
Change in short-term debt	(76,100)	(152,040)
Cash dividend payments on common stock	(41,508)	(39,605)
Other	(2,957)	(372)
Net Cash Provided by (Used in) Financing Activities	104,503	67,888
Increase in cash and cash equivalents	26,278	(2,111)
Cash and cash equivalents, beginning of period	9,648	12,633
Cash and cash equivalents, end of period	35,926	10,522
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	29,829	27,736
Income taxes paid (refunded), net	9,344	(6,096)
Northwest Natural Gas Company [Member]
Operating activities:
Net income	24,247	29,361
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	74,857	66,821
Regulatory amortization of gas reserves	13,711	14,474
Deferred income taxes	(2,407)	(5)
Qualified defined benefit pension plan expense	13,800	10,464
Contributions to qualified defined benefit pension plans	(23,670)	(7,810)
Deferred environmental expenditures, net	(16,469)	(10,992)
Amortization of environmental remediation	6,494	7,258
Regulatory revenue recovery deferral from the TCJA	0	742
Regulatory disallowance of pension costs	0	10,500
Other	(4,410)	7,903
Changes in assets and liabilities:
Receivables, net	78,217	83,581
Inventories	(842)	(3,321)
Income and other taxes	22,104	13,505
Accounts payable	(22,703)	(30,281)
Interest accrued	2,111	3,132
Deferred gas costs	(2,472)	(47,085)
Decoupling mechanism	4,175	11,095
Other, net	(12,030)	(4,878)
Cash provided by operating activities	154,713	154,464
Investing activities:
Capital expenditures	(188,553)	(151,915)
Leasehold improvement expenditures	(7,827)	(13,027)
Proceeds from the sale of assets	8,003	281
Other	(234)	(2,714)
Cash used in investing activities	(188,611)	(167,375)
Financing activities:
Proceeds from Contributions from Parent	0	93,182
Long-term debt issued	150,000	140,000
Long-term debt retired	(75,000)	(10,000)
Proceeds from term loan due within one year	150,000	0
Change in short-term debt	(125,100)	(172,000)
Cash dividend payments on common stock	(41,444)	(39,601)
Other	(3,344)	(343)
Net Cash Provided by (Used in) Financing Activities	55,112	11,238
Increase in cash and cash equivalents	21,214	(1,673)
Cash and cash equivalents, beginning of period	5,919
Cash and cash equivalents, end of period	27,133	6,274
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	28,139	26,927
Income taxes paid (refunded), net	$ 950	$ (6,096)