Consolidated Statement of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities:
Net income	$ 47,498	$ 43,201
Adjustments to reconcile net income to cash provided by operations:
Depreciation, Depletion and Amortization	24,675	21,572
Regulatory amortization of gas reserves	4,087	4,780
Deferred income taxes	(3,422)	6,306
Qualified defined benefit pension plan expense	4,446	3,499
Contributions to qualified defined benefit pension plans	(3,160)	(1,490)
Deferred environmental expenditures, net	(3,981)	(3,685)
Amortization of environmental remediation	4,005	8,947
Regulatory revenue recovery deferral from the TCJA	0	450
Regulatory disallowance of pension costs	0	10,500
Other	6,499	3,171
Changes in assets and liabilities:
Receivables, net	4,845	(4,891)
Inventories	9,571	21,108
Income and other taxes	21,911	7,406
Accounts payable	(23,430)	(14,883)
Interest accrued	1,945	1,927
Deferred gas costs	8,239	(19,182)
Decoupling mechanism	6,137	7,903
Other, net	(6,626)	8,894
Discontinued operations	(376)	(739)
Cash provided by operating activities	102,863	104,794
Investing activities:
Capital expenditures	(57,446)	(48,764)
Acquisitions, net of cash acquired	(37,883)	0
Leasehold improvement expenditures	(6,325)	(940)
Other	919	(1,051)
Discontinued operations	(694)	(301)
Cash used in investing activities	(101,429)	(51,056)
Financing activities:
Proceeds from stock options exercised	68	1,546
Long-term debt issued	150,000	0
Long-term debt retired	(75,000)	0
Proceeds from Short-term Debt	150,000	0
Change in short-term debt	250,900	(41,229)
Cash dividend payments on common stock	(13,834)	(12,935)
Other	(2,137)	(936)
Net Cash Provided by (Used in) Financing Activities	459,997	(53,554)
Increase in cash and cash equivalents	461,431	184
Cash and cash equivalents, beginning of period	9,648
Cash and cash equivalents, end of period	471,079	12,817
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	8,368	7,976
Income taxes paid (refunded), net	(256)	(90)
Northwest Natural Gas Company [Member]
Operating activities:
Net income	49,179	43,895
Adjustments to reconcile net income to cash provided by operations:
Depreciation, Depletion and Amortization	24,190	21,504
Regulatory amortization of gas reserves	4,087	4,780
Deferred income taxes	(3,897)	6,072
Qualified defined benefit pension plan expense	4,446	3,499
Contributions to qualified defined benefit pension plans	(3,160)	(1,490)
Deferred environmental expenditures, net	(3,981)	(3,685)
Amortization of environmental remediation	4,005	8,947
Regulatory revenue recovery deferral from the TCJA	0	450
Regulatory disallowance of pension costs	0	10,500
Other	6,061	3,117
Changes in assets and liabilities:
Receivables, net	2,798	(4,995)
Inventories	9,593	21,097
Income and other taxes	21,748	5,037
Accounts payable	(22,717)	(15,337)
Interest accrued	1,927	1,952
Deferred gas costs	8,239	(19,182)
Decoupling mechanism	6,137	7,903
Other, net	(4,593)	10,639
Cash provided by operating activities	104,062	104,703
Investing activities:
Capital expenditures	(56,234)	(48,658)
Leasehold improvement expenditures	(6,325)	(940)
Other	919	(1,051)
Cash used in investing activities	(61,640)	(50,649)
Financing activities:
Long-term debt issued	150,000	0
Long-term debt retired	(75,000)	0
Proceeds from Short-term Debt	150,000	0
Change in short-term debt	174,900	(41,200)
Cash dividend payments on common stock	(13,796)	(12,935)
Other	(2,190)	(1,033)
Net Cash Provided by (Used in) Financing Activities	383,914	(55,168)
Increase in cash and cash equivalents	426,336	(1,114)
Cash and cash equivalents, beginning of period	5,919
Cash and cash equivalents, end of period	432,255	6,833
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	7,795	7,889
Income taxes paid (refunded), net	$ 950	$ (90)