v3.25.4
Average Annual Total Returns
 10 Months Ended 12 Months Ended 60 Months Ended 73 Months Ended 120 Months Ended
Oct. 31, 2025
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
Old Westbury All Cap Core Fund | Old Westbury All Cap Core Fund            
Prospectus [Line Items]            
Average Annual Return, Percent     10.38% 10.57%   12.89%
Old Westbury All Cap Core Fund | Old Westbury All Cap Core Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent     8.37% 8.81%   11.47%
Old Westbury All Cap Core Fund | Old Westbury All Cap Core Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent     7.55% 8.16%   10.46%
Old Westbury All Cap Core Fund | MSCI ACWI Investable Market Index (Net) (reflects no deduction for fees, expenses or income taxes, except foreign withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent     22.06% 10.75%   11.45%
Old Westbury All Cap Core Fund | 90% MSCI USA Index (Gross) & 10% MSCI ACWI ex USA Index (Net) (reflects no deduction for fees, expenses or income taxes, except foreign withholding taxes for the (Net) index component)            
Prospectus [Line Items]            
Average Annual Return, Percent     19.18% 13.30%   14.18%
Old Westbury Large Cap Strategies Fund | Old Westbury Large Cap Strategies Fund            
Prospectus [Line Items]            
Average Annual Return, Percent     17.51% 9.21%   9.87%
Old Westbury Large Cap Strategies Fund | Old Westbury Large Cap Strategies Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent     14.37% 7.95%   8.77%
Old Westbury Large Cap Strategies Fund | Old Westbury Large Cap Strategies Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent     12.56% 7.16%   7.89%
Old Westbury Large Cap Strategies Fund | MSCI ACWI Investable Market Index (Net) (reflects no deduction for fees, expenses or income taxes, except foreign withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent [1]     22.06% 10.75%   11.45%
Old Westbury Large Cap Strategies Fund | MSCI ACWI Large Cap Index (Net) (reflects no deduction for fees, expenses or income taxes, except foreign withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent     22.96% 11.92%   12.22%
Old Westbury Small & Mid Cap Strategies Fund | Old Westbury Small & Mid Cap Strategies Fund            
Prospectus [Line Items]            
Average Annual Return, Percent     18.03% 3.03%   7.18%
Old Westbury Small & Mid Cap Strategies Fund | Old Westbury Small & Mid Cap Strategies Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent     15.82% 2.01%   5.84%
Old Westbury Small & Mid Cap Strategies Fund | Old Westbury Small & Mid Cap Strategies Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent     12.20% 2.24%   5.52%
Old Westbury Small & Mid Cap Strategies Fund | MSCI ACWI Investable Market Index (Net) (reflects no deduction for fees, expenses or income taxes, except foreign withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent [2]     22.06% 10.75%   11.45%
Old Westbury Small & Mid Cap Strategies Fund | MSCI ACWI SMID Cap Index (Net) (reflects no deduction for fees, expenses or income taxes, except foreign withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent     19.29% 7.28%   9.19%
Old Westbury Credit Income Fund | Old Westbury Credit Income Fund            
Prospectus [Line Items]            
Average Annual Return, Percent     7.70% 0.20%   0.79%
Old Westbury Credit Income Fund | Old Westbury Credit Income Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent     5.31% (1.83%)   (1.23%)
Old Westbury Credit Income Fund | Old Westbury Credit Income Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent     4.52% (0.70%)   (0.25%)
Old Westbury Credit Income Fund | ICE BofA U.S. Broad Market Index (reflects no deduction for fees, expenses, or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent [3]     7.15% (0.42%)   (0.29%)
Old Westbury Credit Income Fund | ICE BofA 1-10 Year U.S. Corporate Index (reflects no deduction for fees, expenses, or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent     7.89% 1.64%   1.91%
Old Westbury Fixed Income Fund | Old Westbury Fixed Income Fund            
Prospectus [Line Items]            
Average Annual Return, Percent     6.46% 0.45%   1.70%
Old Westbury Fixed Income Fund | Old Westbury Fixed Income Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent     4.83% (0.74%)   0.70%
Old Westbury Fixed Income Fund | Old Westbury Fixed Income Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent     3.81% (0.17%)   0.88%
Old Westbury Fixed Income Fund | ICE BofA U.S. Broad Market Index (reflects no deduction for fees, expenses, or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent [4]     7.15% (0.42%)   2.01%
Old Westbury Fixed Income Fund | ICE BofA 1-10 Year AAA-A U.S. Corporate & Government Index (reflects no deduction for fees, expenses, or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent     6.67% 0.86%   2.03%
Old Westbury Short-Term Bond Fund | Old Westbury Short-Term Bond Fund            
Prospectus [Line Items]            
Average Annual Return, Percent   5.14% 5.24%      
Performance Inception Date Feb. 29, 2024          
Old Westbury Short-Term Bond Fund | Old Westbury Short-Term Bond Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent   3.51% 3.57%      
Old Westbury Short-Term Bond Fund | Old Westbury Short-Term Bond Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent   3.23% 3.09%      
Old Westbury Short-Term Bond Fund | ICE BofA U.S. Broad Market Index (reflects no deduction for fees, expenses, or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent [5] 5.53%   7.15%      
Old Westbury Short-Term Bond Fund | ICE BofA 1-3 Year AAA-A U.S. Corporate & Government Index (reflects no deduction for fees, expenses, or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent 5.18%   5.22%      
Old Westbury Municipal Bond Fund | Old Westbury Municipal Bond Fund            
Prospectus [Line Items]            
Average Annual Return, Percent     4.29% 0.48%   1.43%
Old Westbury Municipal Bond Fund | Old Westbury Municipal Bond Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent     4.07% 0.29%   1.28%
Old Westbury Municipal Bond Fund | Old Westbury Municipal Bond Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent     3.42% 0.65%   1.36%
Old Westbury Municipal Bond Fund | ICE BofA U.S. Municipal Securities Index (reflects no deduction for fees, expenses or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent [6]     3.92% 0.81%   2.36%
Old Westbury Municipal Bond Fund | ICE BofA 1-12 Year AAA-AA Municipal Securities Index (reflects no deduction for fees, expenses or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent     4.89% 1.04%   1.85%
Old Westbury California Municipal Bond Fund | Old Westbury California Municipal Bond Fund            
Prospectus [Line Items]            
Average Annual Return, Percent     4.45% 0.68% 1.76%  
Performance Inception Date Dec. 04, 2018          
Old Westbury California Municipal Bond Fund | Old Westbury California Municipal Bond Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent     4.17% 0.45% 1.54%  
Old Westbury California Municipal Bond Fund | Old Westbury California Municipal Bond Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent     3.44% 0.78% 1.60%  
Old Westbury California Municipal Bond Fund | ICE BofA U.S. Municipal Securities Index (reflects no deduction for fees, expenses or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent [7] 2.54%   3.92% 0.81%    
Old Westbury California Municipal Bond Fund | ICE BofA 3-7 Year AAA-AA Municipal Securities Index (reflects no deduction for fees, expenses, or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent 2.01%   4.90% 0.84%    
Old Westbury New York Municipal Bond Fund | Old Westbury New York Municipal Bond Fund            
Prospectus [Line Items]            
Average Annual Return, Percent     4.06% 0.62% 1.75%  
Performance Inception Date Dec. 04, 2018          
Old Westbury New York Municipal Bond Fund | Old Westbury New York Municipal Bond Fund | After Taxes on Distributions            
Prospectus [Line Items]            
Average Annual Return, Percent     3.89% 0.47% 1.58%  
Old Westbury New York Municipal Bond Fund | Old Westbury New York Municipal Bond Fund | After Taxes on Distributions and Sales            
Prospectus [Line Items]            
Average Annual Return, Percent     3.21% 0.75% 1.61%  
Old Westbury New York Municipal Bond Fund | ICE BofA U.S. Municipal Securities Index (reflects no deduction for fees, expenses or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent [8] 2.54%   3.92% 0.81%    
Old Westbury New York Municipal Bond Fund | ICE BofA 3-7 Year AAA-AA Municipal Securities Index (reflects no deduction for fees, expenses, or income and withholding taxes)            
Prospectus [Line Items]            
Average Annual Return, Percent 2.01%   4.90% 0.84%    
[1] As a result of new regulatory requirements, the Fund’s regulatory or primary index previously changed from the MSCI ACWI Large Cap Index (Net) to the MSCI ACWI Investable Market Index (Net).
[2] As a result of new regulatory requirements, the Fund’s regulatory or primary index previously changed from the MSCI ACWI SMID Cap Index (Net) to the MSCI ACWI Investable Market Index (Net).
[3] As a result of new regulatory requirements, the Fund’s regulatory or primary index previously changed from the ICE BofA 1-10 Year U.S. Corporate Index to the ICE BofA U.S. Broad Market Index.
[4] As a result of new regulatory requirements, the Fund’s regulatory or primary index previously changed from the ICE BofA 1-10 Year AAA-A U.S. Corporate & Government Index to the ICE BofA U.S. Broad Market Index.
[5] As a result of new regulatory requirements, the Fund’s regulatory or primary index previously changed from the ICE BofA 1-3 Year AAA-A U.S. Corporate & Government Index to the ICE BofA U.S. Broad Market Index.
[6] As a result of new regulatory requirements, the Fund’s regulatory or primary index previously changed from the ICE BofA 1-12 Year AAA-AA Municipal Securities Index to the ICE BofA U.S. Municipal Securities Index.
[7] As a result of new regulatory requirements, the Fund’s regulatory or primary index previously changed from the ICE BofA 3-7 Year AAA-AA Municipal Securities Index to the ICE BofA U.S. Municipal Securities Index.
[8] As a result of new regulatory requirements, the Fund’s regulatory or primary index previously changed from the ICE BofA 3-7 Year AAA-AA Municipal Securities Index to the ICE BofA U.S. Municipal Securities Index.