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Cover Page - shares
6 Months Ended
Jun. 30, 2021
Jul. 31, 2021
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2021  
Document Transition Report false  
Entity File Number 001-31303  
Entity Registrant Name Black Hills Corporation  
Entity Incorporation, State or Country Code SD  
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  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Title of 12(b) Security Common stock of $1.00 par value  
Trading Symbol BKH  
Security Exchange Name NYSE  
Entity Common Stock, Shares Outstanding   63,480,270
Entity Central Index Key 0001130464  
Amendment Flag false  
Document Fiscal Year Focus 2021  
Document Fiscal Period Focus Q2  
Current Fiscal Year End Date --12-31