Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 26, 2019
Document Information [Line Items]
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001733998
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Registrant Name	NORTHWEST NATURAL HOLDING COMPANY
Entity Common Stock, Shares Outstanding		28,965,723
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Small Business	false
Entity Emerging Growth Company	false
Northwest Natural Gas Company [Member]
Document Information [Line Items]
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0000073020
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Registrant Name	NORTHWEST NATURAL GAS COMPANY
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Small Business	false
Entity Emerging Growth Company	false