v3.26.1
Shareholder Report, Average Annual Return (Details)
6 Months Ended 12 Months Ended 60 Months Ended 120 Months Ended
Jun. 30, 2026
Jun. 30, 2026
Jun. 30, 2026
Jun. 30, 2026
C000025443        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name Longleaf Partners Fund      
C000117771        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name Longleaf Partners Global Fund      
C000025444        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name Longleaf Partners Small-Cap Fund      
Without Sales Load [Member] | C000025443        
Average Annual Return [Line Items]        
Average Annual Return, Percent (0.77%) 2.22% 1.23% 5.98%
Without Sales Load [Member] | C000117771        
Average Annual Return [Line Items]        
Average Annual Return, Percent 1.21% 9.33% 2.74% 7.56%
Without Sales Load [Member] | C000025444        
Average Annual Return [Line Items]        
Average Annual Return, Percent (5.12%) (2.10%) 1.17% 5.30%
S&P 500 Index TR        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name S&P 500<sup style="inset: 1.5px 0px 4px; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 700; grid-area: auto; line-height: 0px; margin: 0px; overflow: visible; position: relative; text-align: center; text-align-last: auto; white-space-collapse: preserve-breaks;">®</sup> Index      
Average Annual Return, Percent 10.21% 22.32% 13.41% 15.51%
MSCI WORLD INDEX Net (USD)        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name MSCI World Index      
Average Annual Return, Percent 9.69% 21.34% 11.47% 13.14%
Russell 2000 Total Return        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name Russell 2000<sup style="inset: 1.5px 0px 4px; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 700; grid-area: auto; line-height: 0px; margin: 0px; overflow: visible; position: relative; text-align: center; text-align-last: auto; white-space-collapse: preserve-breaks;">®</sup> Index      
Average Annual Return, Percent 22.57% 40.78% 6.98% 11.62%
Russell 1000 Value Total Return        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name Russell 1000<sup style="inset: 1.5px 0px 4px; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 700; grid-area: auto; line-height: 0px; margin: 0px; overflow: visible; position: relative; text-align: center; text-align-last: auto; white-space-collapse: preserve-breaks;">®</sup> Value Index      
Average Annual Return, Percent 16.23% 27.09% 11.17% 11.52%
FTSE Developed Index        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name FTSE Developed Index      
Average Annual Return, Percent 11.40% 23.73% 11.68% 13.23%
MSCI World Value Index        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name MSCI World Value Index      
Average Annual Return, Percent 10.50% 20.84% 10.51% 10.16%
Russell 2000 Value Total Return        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name Russell 2000<sup style="inset: 1.5px 0px 4px; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 700; grid-area: auto; line-height: 0px; margin: 0px; overflow: visible; position: relative; text-align: center; text-align-last: auto; white-space-collapse: preserve-breaks;">®</sup> Value Index      
Average Annual Return, Percent 22.99% 43.01% 8.23% 10.89%
Russell 3000 Total Return Index        
Average Annual Return [Line Items]        
Line Graph and Table Measure Name Russell 3000<sup style="inset: 1.5px 0px 4px; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 700; grid-area: auto; line-height: 0px; margin: 0px; overflow: visible; position: relative; text-align: center; text-align-last: auto; white-space-collapse: preserve-breaks;">®</sup> Index      
Average Annual Return, Percent 10.86% 22.81% 12.30% 15.06%