Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 25, 2019
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2019
Entity File Number	1-38681
Entity Registrant Name	NORTHWEST NATURAL HOLDING COMPANY
Entity Incorporation, State or Country Code	OR
Entity Tax Identification Number	82-4710680
Entity Address, Address Line One	220 N.W. Second Avenue
Entity Address, City or Town	Portland
Entity Address, State or Province	OR
Entity Address, Postal Zip Code	97209
City Area Code	(503)
Local Phone Number	226-4211
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock
Trading Symbol	NWN
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		30,435,575
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Central Index Key	0001733998
Northwest Natural Gas Company [Member]
Document Information [Line Items]
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
Entity File Number	1-15973
Entity Registrant Name	NORTHWEST NATURAL GAS COMPANY
Entity Incorporation, State or Country Code	OR
Entity Tax Identification Number	93-0256722
Entity Address, Address Line One	220 N.W. Second Avenue
Entity Address, City or Town	Portland
Entity Address, State or Province	OR
Entity Address, Postal Zip Code	97209
City Area Code	(503)
Local Phone Number	226-4211
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Central Index Key	0000073020