| Document and Entity Information | Mar. 14, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Mar. 14, 2022 |
| Entity File Number | 1-16305 |
| Entity Tax Identification Number | 91-1969407 |
| Entity Registrant Name | PUGET ENERGY INC /WA |
| Entity Incorporation, State or Country Code | WA |
| Entity Address, Address Line One | 355 110th Ave NE |
| Entity Address, City or Town | Bellevue |
| Entity Address, State or Province | WA |
| Entity Address, Postal Zip Code | 98004 |
| City Area Code | 425 |
| Local Phone Number | 454-6363 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001085392 |
| Amendment Flag | false |
