Consolidated Statement of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities:
Net income	$ 42,646	$ 44,296
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	50,511	43,959
Regulatory amortization of gas reserves	8,567	9,467
Deferred income taxes	(2,004)	5,917
Qualified defined benefit pension plan expense	8,892	6,988
Contributions to qualified defined benefit pension plans	(8,470)	(4,650)
Deferred environmental expenditures, net	(9,897)	(7,148)
Amortization of environmental remediation	5,627	6,291
Regulatory revenue recovery deferral from the TCJA	0	639
Regulatory disallowance of pension costs	0	10,500
Other	(5,931)	6,282
Changes in assets and liabilities:
Receivables, net	73,954	69,036
Inventories	(52)	14,929
Income and other taxes	20,966	16,300
Accounts payable	(18,919)	(27,843)
Interest accrued	(217)	520
Deferred gas costs	115	(44,850)
Decoupling mechanism	4,281	8,635
Other, net	(9,976)	(4,797)
Discontinued operations	(547)	638
Cash provided by operating activities	159,546	155,109
Investing activities:
Capital expenditures	(122,282)	(91,147)
Acquisitions, net of cash acquired	(37,940)	(55,811)
Leasehold improvement expenditures	(7,519)	(3,797)
Proceeds from the sale of assets	7,905	250
Other	263	(1,842)
Discontinued operations	(846)	(1,050)
Cash used in investing activities	(160,419)	(153,397)
Financing activities:
Proceeds from stock options exercised	0	1,723
Proceeds from common stock issued	68	93,182
Long-term debt issued	150,000	175,000
Long-term debt retired	(75,000)	0
Proceeds from term loan due within one year	150,000	0
Change in short-term debt	(66,100)	(197,540)
Cash dividend payments on common stock	(27,679)	(25,916)
Other	(3,007)	91
Net Cash Provided by (Used in) Financing Activities	128,282	46,540
Increase in cash and cash equivalents	127,409	48,252
Cash and cash equivalents, beginning of period	9,648
Cash and cash equivalents, end of period	137,057	60,885
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	23,156	19,725
Income taxes paid (refunded), net	544	(6,095)
Northwest Natural Gas Company [Member]
Operating activities:
Net income	44,467	46,949
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	49,176	43,747
Regulatory amortization of gas reserves	8,567	9,467
Deferred income taxes	(2,766)	5,042
Qualified defined benefit pension plan expense	8,892	6,988
Contributions to qualified defined benefit pension plans	(8,470)	(4,650)
Deferred environmental expenditures, net	(9,897)	(7,148)
Amortization of environmental remediation	5,627	6,291
Regulatory revenue recovery deferral from the TCJA	0	639
Regulatory disallowance of pension costs	0	10,500
Other	(6,746)	5,563
Changes in assets and liabilities:
Receivables, net	74,625	73,186
Inventories	249	14,923
Income and other taxes	22,038	7,199
Accounts payable	(22,186)	(23,744)
Interest accrued	(285)	402
Deferred gas costs	115	(44,850)
Decoupling mechanism	4,281	8,635
Other, net	(7,896)	(3,003)
Cash provided by operating activities	159,791	156,136
Investing activities:
Capital expenditures	(118,227)	(90,675)
Leasehold improvement expenditures	(7,519)	(3,797)
Proceeds from the sale of assets	7,905	250
Other	269	(1,842)
Cash used in investing activities	(117,572)	(96,064)
Financing activities:
Proceeds from Contributions from Parent	0	93,182
Long-term debt issued	150,000	140,000
Long-term debt retired	(75,000)	0
Proceeds from term loan due within one year	150,000	0
Change in short-term debt	(122,100)	(217,500)
Cash dividend payments on common stock	(27,614)	(25,914)
Other	(3,140)	77
Net Cash Provided by (Used in) Financing Activities	72,146	(10,155)
Increase in cash and cash equivalents	114,365	49,917
Cash and cash equivalents, beginning of period	5,919
Cash and cash equivalents, end of period	120,284	57,864
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	21,794	19,529
Income taxes paid (refunded), net	$ 950	$ (6,095)