Leases - Lease Revenue - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Lessor, Lease, Description [Line Items]
Lessor, Sales-type Lease, Renewal Term	50 years		50 years
Lessor, Sales-type Lease, Term of Contract	30 years		30 years
Residual Value of Leased Asset	$ 5,000	$ 4,600	$ 5,000	$ 4,600	$ 4,700
Lease Revenue [Abstract]
Total lease revenue	300	100	400	400
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	158		158
Lessor, Operating Lease, Payment to be Received, Year One	127		127
Operating Lease, Payments to be Received, Two Years	128		128
Operating Lease, Payments to be Received, Three Years	120		120
Operating Lease, Payments to be Received, Four Years	92		92
Operating Lease, Payments to be Received, Thereafter	936		936
Total minimum lease payments	1,561		1,561
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	4,375		4,375
Lease Payments to be Received, Two Years	16,684		16,684
Lease Payments to be Received, Three Years	15,995		15,995
Lease Payments to be Received, Four Years	15,426		15,426
Lease Payments to be Received, Five Years	14,993		14,993
Lease Payments to be Received, Thereafter	237,756		237,756
Total minimum lease payments	305,229		305,229
Northwest Natural Gas Company [Member]
Lease Revenue [Abstract]
Operating leases	19	18	56	61
Sales-type leases	4,279	4,367	12,839	13,104
Total lease revenue	4,298	$ 4,385	12,895	$ 13,165
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	145		145
Lessor, Operating Lease, Payment to be Received, Year One	76		76
Operating Lease, Payments to be Received, Two Years	76		76
Operating Lease, Payments to be Received, Three Years	67		67
Operating Lease, Payments to be Received, Four Years	36		36
Operating Lease, Payments to be Received, Thereafter	22		22
Total minimum lease payments	422		422
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	4,362		4,362
Lease Payments to be Received, Two Years	16,633		16,633
Lease Payments to be Received, Three Years	15,943		15,943
Lease Payments to be Received, Four Years	15,373		15,373
Lease Payments to be Received, Five Years	14,937		14,937
Lease Payments to be Received, Thereafter	236,842		236,842
Total minimum lease payments	304,090		304,090
Other Northwest Holdings [Member]
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	13		13
Lessor, Operating Lease, Payment to be Received, Year One	51		51
Operating Lease, Payments to be Received, Two Years	52		52
Operating Lease, Payments to be Received, Three Years	53		53
Operating Lease, Payments to be Received, Four Years	56		56
Operating Lease, Payments to be Received, Thereafter	914		914
Total minimum lease payments	1,139		1,139
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	13		13
Lease Payments to be Received, Two Years	51		51
Lease Payments to be Received, Three Years	52		52
Lease Payments to be Received, Four Years	53		53
Lease Payments to be Received, Five Years	56		56
Lease Payments to be Received, Thereafter	914		914
Total minimum lease payments	$ 1,139		$ 1,139
Compressed Natural Gas Lease [Member]
Lessor, Lease, Description [Line Items]
Lessor, Sales-type Lease, Term of Contract	10 years		10 years
Residual Value of Leased Asset	$ 0		$ 0
Variable Lease, Payment			0
North Mist Lease [Member]
Lessor, Lease, Description [Line Items]
Residual Value of Leased Asset	0		0
Variable Lease, Payment			0
Sales-type Lease [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type Lease, Payments to be Received, Remainder of Fiscal Year	4,217		4,217
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	16,557		16,557
Sales-type Lease, Payments to be Received, Two Years	15,867		15,867
Sales-type Lease, Payments to be Received, Three Years	15,306		15,306
Sales-type Lease, Payments to be Received, Four Years	14,901		14,901
Sales-type Lease, Payments to be Received, Thereafter	236,820		236,820
Total minimum lease payments	303,668		303,668
Less: imputed interest	168,188		168,188
Total leases receivable	135,480		135,480
Sales-type Lease [Member] | Northwest Natural Gas Company [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type Lease, Payments to be Received, Remainder of Fiscal Year	4,217		4,217
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	16,557		16,557
Sales-type Lease, Payments to be Received, Two Years	15,867		15,867
Sales-type Lease, Payments to be Received, Three Years	15,306		15,306
Sales-type Lease, Payments to be Received, Four Years	14,901		14,901
Sales-type Lease, Payments to be Received, Thereafter	236,820		236,820
Total minimum lease payments	303,668		303,668
Less: imputed interest	168,188		168,188
Total leases receivable	135,480		135,480
Sales-type Lease [Member] | Other Northwest Holdings [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type Lease, Payments to be Received, Remainder of Fiscal Year	0		0
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	0		0
Sales-type Lease, Payments to be Received, Two Years	0		0
Sales-type Lease, Payments to be Received, Three Years	0		0
Sales-type Lease, Payments to be Received, Four Years	0		0
Sales-type Lease, Payments to be Received, Thereafter	0		0
Total minimum lease payments	$ 0		$ 0