Document and Entity Information
Document and Entity Information Document | May 17, 2022 |
Cover [Abstract] | |
Document Type | 8-K |
Document Period End Date | Jun. 24, 2022 |
Entity Registrant Name | NorthWestern Corporation |
Entity Central Index Key | 0000073088 |
Amendment Flag | false |
City Area Code | 605 |
Local Phone Number | 978-2900 |
Written Communications | false |
Soliciting Material | false |
Pre-commencement Tender Offer | false |
Pre-commencement Issuer Tender Offer | false |
Entity Emerging Growth Company | false |