| Cover Page | Jul. 02, 2021 | Feb. 08, 2021 |
| Document Information [Line Items] | ||
| Amendment Flag | false | |
| Entity Registrant Name | XCEL ENERGY INC | |
| Entity Central Index Key | 0000072903 | |
| Entity Incorporation, State or Country Code | MN | |
| Document Type | 8-K | |
| Document Period End Date | Jul. 2, 2021 | |
| Entity File Number | 001-3034 | |
| Entity Tax Identification Number | 41-0448030 | |
| Entity Address, Address Line One | 414 Nicollet Mall | |
| Entity Address, City or Town | Minneapolis | |
| Entity Address, State or Province | MN | |
| Entity Address, Postal Zip Code | 55401 | |
| City Area Code | (612) | |
| Local Phone Number | 330-5500 | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Title of 12(b) Security | Common Stock, $2.50 par value per share | |
| Trading Symbol | XEL | |
| Security Exchange Name | NASDAQ | |
| Entity Emerging Growth Company | false | |
| SOUTHWESTERN PUBLIC SERVICE CO [Member] | ||
| Document Information [Line Items] | ||
| Entity Registrant Name | NORTHER STATES POWER CO /WI/ | |
| Entity Central Index Key | 0000072909 | |
| Entity Incorporation, State or Country Code | WI | |
| Entity Address, Address Line One | 1414 West Hamilton Avenue | |
| Entity Address, City or Town | Eau Claire | |
| Entity Address, State or Province | WI | |
| Entity Address, Postal Zip Code | 54701 | |
| City Area Code | (715) | |
| Local Phone Number | 839-2625 | |
| Northern States Power Co. WISC | ||
| Document Information [Line Items] | ||
| Entity File Number | 001-03140 | |
| Entity Tax Identification Number | 39-0508315 |
