v3.26.1
Average Annual Total Returns
 12 Months Ended 60 Months Ended 120 Months Ended 134 Months Ended 386 Months Ended 492 Months Ended
Apr. 29, 2026
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
HEARTLAND MID CAP VALUE FUND | Investor Class              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return Before Taxes            
Average Annual Return, Percent   0.12% 7.88% 9.55% 7.96%    
Performance Inception Date Oct. 31, 2014            
HEARTLAND MID CAP VALUE FUND | Investor Class | After Taxes on Distributions              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions            
Average Annual Return, Percent   (0.39%) 5.92% 8.03% 6.56%    
HEARTLAND MID CAP VALUE FUND | Investor Class | After Taxes on Distributions and Sales              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares            
Average Annual Return, Percent   0.43% 5.88% 7.47% 6.16%    
HEARTLAND MID CAP VALUE FUND | Institutional Class              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return Before Taxes            
Average Annual Return, Percent   0.38% 8.14% 9.82% 8.23%    
Performance Inception Date Oct. 31, 2014            
HEARTLAND MID CAP VALUE FUND | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Russell 3000® Index (reflects no deduction for fees, expenses or taxes)            
Average Annual Return, Percent   17.15% 13.15% 14.29% 12.95%    
HEARTLAND MID CAP VALUE FUND | Russell Midcap® Value Index (reflects no deduction for fees, expenses or taxes)              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Russell Midcap® Value Index (reflects no deduction for fees, expenses or taxes)            
Average Annual Return, Percent   11.05% 9.83% 9.78% 8.45%    
HEARTLAND VALUE PLUS FUND | Investor Class              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return Before Taxes            
Average Annual Return, Percent   1.06% 4.01% 7.65%   9.00%  
Performance Inception Date Oct. 26, 1993            
HEARTLAND VALUE PLUS FUND | Investor Class | After Taxes on Distributions              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions            
Average Annual Return, Percent   0.92% 2.47% 6.74%   7.73%  
HEARTLAND VALUE PLUS FUND | Investor Class | After Taxes on Distributions and Sales              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares            
Average Annual Return, Percent   0.74% 2.93% 6.10%   7.43%  
HEARTLAND VALUE PLUS FUND | Institutional Class              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return Before Taxes            
Average Annual Return, Percent   1.30% 4.27% 7.89%   9.14%  
Performance Inception Date Oct. 26, 1993            
HEARTLAND VALUE PLUS FUND | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Russell 3000® Index (reflects no deduction for fees, expenses or taxes)            
Average Annual Return, Percent   17.15% 13.15% 14.29%   10.60%  
HEARTLAND VALUE PLUS FUND | Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)            
Average Annual Return, Percent   12.59% 8.88% 9.27%   9.35%  
HEARTLAND VALUE FUND | Investor Class              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return Before Taxes            
Average Annual Return, Percent   15.98% 11.49% 9.80%     11.32%
Performance Inception Date Dec. 28, 1984            
HEARTLAND VALUE FUND | Investor Class | After Taxes on Distributions              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions            
Average Annual Return, Percent   13.66% 9.46% 8.27%     9.53%
HEARTLAND VALUE FUND | Investor Class | After Taxes on Distributions and Sales              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares            
Average Annual Return, Percent   11.16% 8.79% 7.66%     9.35%
HEARTLAND VALUE FUND | Institutional Class              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Return Before Taxes            
Average Annual Return, Percent   16.17% 11.65% 9.97%     11.41%
Performance Inception Date Dec. 28, 1984            
HEARTLAND VALUE FUND | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Russell 3000® Index (reflects no deduction for fees, expenses or taxes)            
Average Annual Return, Percent   17.15% 13.15% 14.29%     11.77%
HEARTLAND VALUE FUND | Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)              
Prospectus [Line Items]              
Average Annual Return, Label [Optional Text] Russell 2000® Value Index (reflects no deduction for fees, expenses or taxes)            
Average Annual Return, Percent   12.59% 8.88% 9.27%     10.50%