Consolidated Statement of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating activities:
Net income	$ 44,296	$ 40,539
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	43,959	42,022
Regulatory amortization of gas reserves	9,467	7,816
Deferred income taxes	5,917	11,227
Qualified defined benefit pension plan expense	6,988	2,876
Contributions to qualified defined benefit pension plans	(4,650)	(5,570)
Deferred environmental expenditures, net	(7,148)	(7,330)
Amortization of environmental remediation	6,291	6,506
Regulatory revenue recovery deferral from the TCJA	639	9,212
Regulatory disallowance of pension costs	10,500	0
Other	6,282	810
Changes in assets and liabilities:
Receivables, net	69,036	79,332
Inventories	14,929	4,803
Income and other taxes	16,300	(11,967)
Accounts payable	(27,843)	(26,613)
Interest accrued	520	(121)
Deferred gas costs	(44,850)	4,787
Decoupling mechanism	8,635	4,613
Other, net	(4,797)	(990)
Discontinued operations	638	700
Cash provided by operating activities	155,109	162,652
Investing activities:
Capital expenditures	(91,147)	(102,370)
Acquisitions, net of cash acquired	(55,811)	0
Other	(5,389)	195
Discontinued operations	(1,050)	(283)
Cash used in investing activities	(153,397)	(102,458)
Financing activities:
Proceeds from stock options exercised	1,723	45
Proceeds from common stock issued	93,182	0
Long-term debt issued	175,000	0
Long-term debt retired	0	(22,000)
Change in short-term debt	(197,540)	(7,100)
Cash dividend payments on common stock	(25,916)	(25,577)
Other	91	(279)
Net Cash Provided by (Used in) Financing Activities	46,540	(54,911)
Increase in cash and cash equivalents	48,252	5,283
Cash and cash equivalents, beginning of period	12,633	3,472
Cash and cash equivalents, end of period	60,885	8,755
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	19,725	17,117
Income taxes paid (refunded), net	(6,095)	13,347
Northwest Natural Gas Company [Member]
Operating activities:
Net income	46,949	40,539
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	43,747	41,958
Regulatory amortization of gas reserves	9,467	7,816
Deferred income taxes	5,042	9,387
Qualified defined benefit pension plan expense	6,988	2,876
Contributions to qualified defined benefit pension plans	(4,650)	(5,570)
Deferred environmental expenditures, net	(7,148)	(7,330)
Amortization of environmental remediation	6,291	6,506
Regulatory revenue recovery deferral from the TCJA	639	9,212
Regulatory disallowance of pension costs	10,500	0
Other	5,563	1,180
Changes in assets and liabilities:
Receivables, net	73,186	79,333
Inventories	14,923	4,434
Income and other taxes	7,199	(11,957)
Accounts payable	(23,744)	(26,195)
Interest accrued	402	(121)
Deferred gas costs	(44,850)	4,787
Decoupling mechanism	8,635	4,613
Other, net	(3,003)	(1,990)
Discontinued operations	0	3,104
Cash provided by operating activities	156,136	162,582
Investing activities:
Capital expenditures	(90,675)	(102,370)
Other	(5,389)	195
Discontinued operations	0	(284)
Cash used in investing activities	(96,064)	(102,459)
Financing activities:
Capital contribution from parent	93,182	0
Long-term debt issued	140,000	0
Long-term debt retired	0	(22,000)
Change in short-term debt	(217,500)	(7,100)
Cash dividend payments on common stock	(25,914)	(25,577)
Other	77	(234)
Net Cash Provided by (Used in) Financing Activities	(10,155)	(54,911)
Increase in cash and cash equivalents	49,917	5,212
Cash and cash equivalents, beginning of period	7,947	3,110
Cash and cash equivalents, end of period	57,864	8,322
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	19,529	17,117
Income taxes paid (refunded), net	$ (6,095)	$ 13,347