Leases - Lease Expense - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2023 |
Sep. 30, 2022 |
Sep. 30, 2023 |
Sep. 30, 2022 |
|
| Lease Expense [Abstract] | ||||
| Operating Lease, Expense | $ 1,868 | $ 1,774 | $ 5,513 | $ 5,257 |
| Short-term Lease, Cost | $ 198 | 105 | $ 556 | 684 |
| Lessee, Operating Lease, Maximum Term of Short-term Leases not recorded on the Balance Sheet | 12 months | 12 months | ||
| Minimum [Member] | ||||
| Operating Lease Terms [Abstract] | ||||
| Lessee, Operating Lease, Term of Contract | 3 months | 3 months | ||
| Maximum [Member] | ||||
| Operating Lease Terms [Abstract] | ||||
| Lessee, Operating Lease, Term of Contract | 17 years | 17 years | ||
| Northwest Natural Gas Company [Member] | ||||
| Lease Expense [Abstract] | ||||
| Operating Lease, Expense | $ 1,817 | 1,767 | $ 5,382 | 5,235 |
| Short-term Lease, Cost | 198 | 105 | 556 | 684 |
| Other Northwest Holdings [Member] | Corporate, Non-Segment [Member] | ||||
| Lease Expense [Abstract] | ||||
| Operating Lease, Expense | $ 51 | $ 7 | $ 131 | $ 22 |