Consolidated Statement of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities:
Net income	$ 56,239	$ 59,517
Adjustments to reconcile net income to cash provided by operations:
Depreciation	28,429	28,097
Regulatory amortization of gas reserves	1,481	3,634
Deferred income taxes	8,780	3,145
Qualified defined benefit pension plan expense	1,441	3,937
Contributions to qualified defined benefit pension plans	0	(4,540)
Deferred environmental expenditures, net	(4,345)	(4,270)
Environmental remediation expense	4,703	3,777
Asset optimization revenue sharing bill credits	(41,102)	(9,053)
Other	6,325	6,134
Changes in assets and liabilities:
Receivables, net	38,664	1,044
Inventories	23,885	16,454
Income and other taxes	14,436	22,975
Accounts payable	(16,487)	(2,329)
Deferred gas costs	11,728	(28,912)
Asset optimization revenue sharing	(646)	34,633
Decoupling mechanism	4,434	656
Other, net	3,072	2,166
Cash provided by operating activities	141,037	137,065
Investing activities:
Capital expenditures	(68,514)	(65,702)
Acquisitions, net of cash acquired	0	(42)
Proceeds from the sale of assets	195	1,960
Other	(1,431)	(91)
Cash used in investing activities	(69,750)	(63,875)
Financing activities:
Proceeds from common stock issued, net	9,938	0
Repayment of commercial paper, maturities greater than three months	0	(100,000)
Changes in other short-term debt, net	(57,000)	31,700
Cash dividend payments on common stock	(14,452)	(13,858)
Other	(1,250)	(974)
Cash used in financing activities	(62,764)	(83,132)
Cash, cash equivalents and restricted cash	35,643	25,512
Increase (decrease) in cash, cash equivalents and restricted cash	8,523	(9,942)
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	7,977	8,976
Income taxes paid, net of refunds	773	800
Northwest Natural Gas Company [Member]
Operating activities:
Net income	57,416	60,111
Adjustments to reconcile net income to cash provided by operations:
Depreciation	27,637	27,169
Regulatory amortization of gas reserves	1,481	3,634
Deferred income taxes	8,744	2,592
Qualified defined benefit pension plan expense	1,441	3,937
Contributions to qualified defined benefit pension plans	0	(4,540)
Deferred environmental expenditures, net	(4,345)	(4,270)
Environmental remediation expense	4,703	3,777
Asset optimization revenue sharing bill credits	(41,102)	(9,053)
Other	5,786	5,454
Changes in assets and liabilities:
Receivables, net	36,920	421
Inventories	23,995	16,588
Income and other taxes	12,383	21,488
Accounts payable	(15,525)	(711)
Deferred gas costs	11,728	(28,912)
Asset optimization revenue sharing	(646)	34,633
Decoupling mechanism	4,434	656
Other, net	3,180	3,299
Cash provided by operating activities	138,230	136,273
Investing activities:
Capital expenditures	(64,317)	(64,098)
Proceeds from the sale of assets	195	1,960
Other	(1,431)	(91)
Cash used in investing activities	(65,553)	(62,229)
Financing activities:
Capital contributions from parent	527	0
Repayment of commercial paper, maturities greater than three months	0	(100,000)
Changes in other short-term debt, net	(57,000)	43,700
Cash dividend payments on common stock	(14,338)	(13,951)
Other	(1,215)	(1,509)
Cash used in financing activities	(72,026)	(71,760)
Cash, cash equivalents and restricted cash	21,483	18,023
Increase (decrease) in cash, cash equivalents and restricted cash	651	2,284
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	7,288	8,585
Income taxes paid, net of refunds	$ 3,300	$ 2,880