Consolidated Statement of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating activities:
Net income	$ 71,671	$ 56,239
Adjustments to reconcile net income to cash provided by operations:
Depreciation	31,465	28,429
Regulatory amortization of gas reserves	833	1,481
Deferred income taxes	5,228	8,780
Qualified defined benefit pension plan (benefit) expense	(791)	1,441
Deferred environmental expenditures, net	(4,113)	(4,345)
Environmental remediation expense	5,375	4,703
Asset optimization revenue sharing bill credits	(10,471)	(41,102)
Other	8,509	6,325
Changes in assets and liabilities:
Receivables, net	38,727	38,664
Inventories	46,129	23,885
Income and other taxes	25,567	14,436
Accounts payable	(47,773)	(16,487)
Deferred gas costs	(11,300)	11,728
Asset optimization revenue sharing	7,769	(646)
Decoupling mechanism	(1,303)	4,434
Change in Cloud-based software Assets	(3,673)	(416)
Other, net	15,012	3,488
Cash provided by operating activities	176,861	141,037
Investing activities:
Capital expenditures	(71,265)	(68,514)
Acquisitions, net of cash acquired	(468)	0
Other	(1,285)	(1,236)
Cash used in investing activities	(73,018)	(69,750)
Financing activities:
Proceeds from common stock issued, net	16,669	9,938
Long-term debt issued	200,000	0
Changes in other short-term debt, net	(185,700)	(57,000)
Cash dividend payments on common stock	(16,532)	(14,452)
Other	(3,250)	(1,250)
Cash used in financing activities	11,187	(62,764)
Cash, cash equivalents and restricted cash	155,994	35,643
Increase (decrease) in cash, cash equivalents and restricted cash	115,030	8,523
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	14,904	7,977
Income taxes paid, net of refunds	1,300	773
Northwest Natural Gas Company [Member]
Operating activities:
Net income	75,540	57,416
Adjustments to reconcile net income to cash provided by operations:
Depreciation	30,144	27,637
Regulatory amortization of gas reserves	833	1,481
Deferred income taxes	6,495	8,744
Qualified defined benefit pension plan (benefit) expense	(791)	1,441
Deferred environmental expenditures, net	(4,113)	(4,345)
Environmental remediation expense	5,375	4,703
Asset optimization revenue sharing bill credits	(10,471)	(41,102)
Other	7,851	5,786
Changes in assets and liabilities:
Receivables, net	36,671	36,920
Inventories	46,509	23,995
Income and other taxes	20,310	12,383
Accounts payable	(48,531)	(15,525)
Deferred gas costs	(11,299)	11,728
Asset optimization revenue sharing	7,769	(646)
Decoupling mechanism	(1,303)	4,434
Change in Cloud-based software Assets	(3,673)	(416)
Other, net	17,515	3,596
Cash provided by operating activities	174,831	138,230
Investing activities:
Capital expenditures	(63,598)	(64,317)
Other	(1,284)	(1,236)
Cash used in investing activities	(64,882)	(65,553)
Financing activities:
Capital contributions from parent	8	527
Long-term debt issued	200,000	0
Changes in other short-term debt, net	(170,200)	(57,000)
Cash dividend payments on common stock	(16,552)	(14,338)
Other	(2,972)	(1,215)
Cash used in financing activities	10,284	(72,026)
Cash, cash equivalents and restricted cash	144,904	21,483
Increase (decrease) in cash, cash equivalents and restricted cash	120,233	651
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	10,522	7,288
Income taxes paid, net of refunds	$ 6,565	$ 3,300