| Document and Entity Information Document | Sep. 16, 2020 |
| Cover Page [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Sep. 16, 2020 |
| Entity Registrant Name | Black Hills Corporation |
| Entity Incorporation, State or Country Code | SD |
| Entity File Number | 001-31303 |
| Entity Tax Identification Number | 46-0458824 |
| Entity Address, Address Line One | 7001 Mount Rushmore Road |
| Entity Address, City or Town | Rapid City |
| Entity Address, State or Province | SD |
| Entity Address, Postal Zip Code | 57702 |
| City Area Code | 605 |
| Local Phone Number | 721-1700 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock of $1.00 par value |
| Trading Symbol | BKH |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001130464 |
| Amendment Flag | false |
