| Shareholder Report | 8 Months Ended | 12 Months Ended | 120 Months Ended |
| Oct. 31, 2024 USD ($) Holding | Oct. 31, 2024 USD ($) Holding | Oct. 31, 2024 USD ($) Holding |
| Shareholder Report [Line Items] | | | |
| Document Type | | N-CSR | |
| Amendment Flag | | false | |
| Registrant Name | | Old Westbury Funds, Inc. | |
| Entity Central Index Key | | 0000909994 | |
| Entity Investment Company Type | | N-1A | |
| Document Period End Date | | Oct. 31, 2024 | |
| C000004836 | | | |
| Shareholder Report [Line Items] | | | |
| Fund Name | | All Cap Core Fund | |
| Trading Symbol | | OWACX | |
| Annual or Semi-Annual Statement [Text Block] | | This annual shareholder report contains important information about the Old Westbury All Cap Core Fund (the "Fund") for the period of November 1, 2023 to October 31, 2024 (the "reporting period"). | |
| Shareholder Report Annual or Semi-Annual | | Annual Shareholder Report | |
| Additional Information [Text Block] | | You can find additional information about the Fund at www.oldwestburyfunds.com | |
| Additional Information Phone Number | | (800) 607-2200 | |
| Additional Information Website | | www.oldwestburyfunds.com</span>" id="sjs-C18"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: justify;">www.oldwestburyfunds.com</span> | |
| Expenses [Text Block] | | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Old Westbury All Cap Core Fund $112 0.95% | |
| Expenses Paid, Amount | | $ 112 | |
| Expense Ratio, Percent | | 0.95% | |
| Factors Affecting Performance [Text Block] | | What drove Fund performance during the past 12 months? Global equities overall enjoyed strong performance during the reporting period, bolstered by a resilient economic backdrop along with heightened enthusiasm for advances in information technology and healthcare. The U.S. continued to lead global markets due primarily to its significant exposure to several large companies with strong fundamentals and earnings growth, such as NVIDIA, Microsoft, and Apple. International markets modestly underperformed global markets, driven by relatively slower economic growth in Europe and Asia. What contributed to performance? Performance of the Fund’s primary benchmark is provided in the table below. Here, we discuss the Fund’s performance against its secondary benchmark, a blended index (90% MSCI USA Index & 10% MSCI ACWI ex USA Index (Net)). The Fund’s overweight to the U.S. helped performance during the reporting period. Stock selection also proved beneficial. Within the consumer discretionary sector, Fund holdings Mercardo Libre, Hilton Worldwide, and Amazon were all strong performers. Having no exposure to large-benchmark-weight Tesla, which underperformed during the reporting period, also helped the Fund. Within consumer staples, Fund holdings Walmart, U.S. Foods, and Costco all outperformed, benefiting from consumer trends in their industries, also contributing to performance of the Fund. Within information technology, overweight positions in NVIDIA and Motorola Solutions made positive contributions to performance. What detracted from performance? The largest detractor from performance was the Fund holding cash in an up market. Stock selection also played a role. Within the energy sector, Fund holding SLB (formerly Schlumberger) underperformed during the reporting period while large-benchmark-weight Exxon Mobil, which the Fund did not own, proved an outperformer for the sector. Within healthcare, Fund holdings United Health Group and IQVIA lagged, while Eli Lilly, which was not owned by the Fund, saw strong performance. | |
| Line Graph [Table Text Block] | | Old Westbury All Cap Core Fund MSCI ACWI Investable Market Index (Net) 90% MSCI USA Index & 10% MSCI ACWI ex USA Index (Net) 2014 $10,000 $10,000 $10,000 2015 $9,830 $10,010 $10,410 2016 $9,901 $10,244 $10,819 2017 $12,061 $12,653 $13,368 2018 $12,736 $12,533 $14,118 2019 $14,728 $14,038 $16,102 2020 $17,279 $14,644 $17,729 2021 $24,150 $20,236 $25,168 2022 $18,996 $16,145 $20,810 2023 $21,022 $17,667 $22,959 2024 $28,453 $23,379 $31,446 | |
| Average Annual Return [Table Text Block] | | Fund 1 Year 5 Years 10 Years Old Westbury All Cap Core Fund 35.35% 14.08% 11.02% MSCI ACWI Investable Market Index (Net) 32.33% 10.74% 8.86% 90% MSCI USA Index & 10% MSCI ACWI ex USA Index (Net) 36.96% 14.32% 12.14% | |
| AssetsNet | $ 3,532,016,610 | $ 3,532,016,610 | $ 3,532,016,610 |
| Holdings Count | Holding | 97 | 97 | 97 |
| Advisory Fees Paid, Amount | | $ 22,590,266 | |
| InvestmentCompanyPortfolioTurnover | | 41% | |
| Additional Fund Statistics [Text Block] | | Fund Statistics as of 10/31/2024 Total Net Assets $3,532,016,610 # of Portfolio Holdings 97 Portfolio Turnover Rate 41% Total Advisory Fees Paid (Net of Waivers) $22,590,266 | |
| Holdings [Text Block] | | Sector Weightings (as a % of Net Assets) as of 10/31/2024 Information Technology 26.6% Industrials 11.9% Financial Services 11.6% Consumer Discretionary 10.4% Health Care 9.4% Communication Services 8.7% Consumer Staples 4.9% Banks 3.8% Other Sectors 7.3% Other Assets and Liabilities 5.4% | |
| Largest Holdings [Text Block] | | Top Ten Holdings (as a % of Net Assets) as of 10/31/2024 NVIDIA Corp. 5.2% Microsoft Corp. 5.1% Apple, Inc. 4.5% Alphabet, Inc. 4.0% Amazon.com, Inc. 3.5% Visa, Inc. 3.0% Meta Platforms, Inc. 2.9% UnitedHealth Group, Inc. 2.7% JPMorgan Chase & Co. 2.0% Intercontinental Exchange, Inc. 1.9% | |
| Material Fund Change [Text Block] | | Material Fund Changes This is a summary of certain changes to the Fund for the reporting period. For more complete information, you may review the Fund's next prospectus, which we expect to be available by March 1, 2025 at www.oldwestburyfunds.com Effective November 1, 2023, Bessemer Investment Management LLC, the Fund's investment adviser, has contractually committed through October 31, 2026 to waive its advisory fees to the extent necessary to maintain the net operating expense ratio of the Fund, excluding Fund transaction costs, investment interest expense, dividend expenses associated with securities sold short and Acquired Fund Fees and Expenses (if any), at 0.95%. | |
| Updated Prospectus Phone Number | | (800) 607-2200 | |
| Updated Prospectus Web Address | | www.oldwestburyfunds.com</span>" id="sjs-C34"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: left;">www.oldwestburyfunds.com</span> | |
| C000206042 | | | |
| Shareholder Report [Line Items] | | | |
| Fund Name | | California Municipal Bond Fund | |
| Trading Symbol | | OWCAX | |
| Annual or Semi-Annual Statement [Text Block] | | This annual shareholder report contains important information about the Old Westbury California Municipal Bond Fund (the "Fund") for the period of November 1, 2023 to October 31, 2024 (the "reporting period"). | |
| Shareholder Report Annual or Semi-Annual | | Annual Shareholder Report | |
| Additional Information [Text Block] | | You can find additional information about the Fund at www.oldwestburyfunds.com | |
| Additional Information Phone Number | | (800) 607-2200 | |
| Additional Information Website | | www.oldwestburyfunds.com</span>" id="sjs-C43"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: justify;">www.oldwestburyfunds.com</span> | |
| Expenses [Text Block] | | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Old Westbury California Municipal Bond Fund $59 0.57% | |
| Expenses Paid, Amount | | $ 59 | |
| Expense Ratio, Percent | | 0.57% | |
| Factors Affecting Performance [Text Block] | | What drove Fund performance during the past 12 months? Throughout the reporting period, U.S. fixed income market performance was driven by an evolution in U.S. Federal Reserve policy from interest rate increases to interest rate cuts, heightened investor demand for bonds amid economic uncertainty, and market volatility influenced by fluctuating economic indicators and the presidential election. In the municipal bond market, supply and demand garnered much of investors’ focus. Supply surprised significantly to the upside after two years of paltry issuance as issuers looked to front-run election-related volatility, while demand surged as investors looked to capitalize upon particularly attractive tax-exempt yields. California credits in particular experienced very strong demand throughout the reporting period given the onerous tax burden in the state; new issues tended to price at much tighter spreads than the rest of the market and also tended to be highly oversubscribed. What contributed to performance? Performance of the Fund’s primary benchmark is provided in the table below. Here, we discuss the Fund’s performance against its secondary benchmark, the ICE BofA 3-7 Year AAA-AA Municipal Securities Index. Throughout the reporting period, the Fund maintained a longer duration posture compared to its secondary benchmark, reflective of strong municipal fundamentals, a favorable supply/demand mix, attractive tax-adjusted yields, and a high-tax environment conducive to elevated demand for the asset class, which contributed to the performance of the Fund. Despite broad market volatility, particularly in the run-up to the presidential election, the investment team’s investment thesis remained unchanged: the belief that ultimately, the aggressive U.S. Federal Reserve interest rate hiking cycle would result in lower inflation and slower domestic growth, driving higher demand for municipals with yields at some of the most attractive levels in the past 20 years. As a result, the longer-duration posture of the Fund was the top contributor to performance. What detracted from performance? Despite the stronger gains, certain headwinds did inhibit broader outperformance. In particular, the credit rating profile of the Fund’s portfolio holdings (overweights to AAA and A credits, funded by an underweight to AA credits) created a slight performance drag as AA spreads in the intermediate part of the yield curve compressed more than comparable-maturity A spreads, which detracted from performance. | |
| Line Graph [Table Text Block] | | Old Westbury California Municipal Bond Fund ICE BofA U.S. Municipal Securities Index ICE BofA 3-7 Year AAA-AA Municipal Securities Index 12/04/2018 $10,000 $10,000 $10,000 2019 $10,478 $10,841 $10,550 2020 $10,823 $11,221 $10,957 2021 $10,818 $11,569 $10,993 2022 $9,984 $10,122 $10,149 2023 $10,168 $10,381 $10,312 2024 $10,800 $11,453 $10,966 | |
| Average Annual Return [Table Text Block] | | Fund 1 Year 5 Years Since Inception
(December 4, 2018) Old Westbury California Municipal Bond Fund 6.21% 0.61% 1.31% ICE BofA U.S. Municipal Securities Index 10.33% 1.10% 2.32% ICE BofA 3-7 Year AAA-AA Municipal Securities Index 6.35% 0.78% 1.57% | |
| Performance Inception Date | | | Dec. 04, 2018 |
| AssetsNet | $ 368,328,999 | $ 368,328,999 | $ 368,328,999 |
| Holdings Count | Holding | 96 | 96 | 96 |
| Advisory Fees Paid, Amount | | $ 958,754 | |
| InvestmentCompanyPortfolioTurnover | | 35% | |
| Additional Fund Statistics [Text Block] | | Fund Statistics as of 10/31/2024 Total Net Assets $368,328,999 # of Portfolio Holdings 96 Portfolio Turnover Rate 35% Total Advisory Fees Paid (Net of Waivers) $958,754 | |
| Holdings [Text Block] | | State Diversification (as a % of Net Assets) as of 10/31/2024 California 92.7% Other Assets and Liabilities 7.3% | |
| Largest Holdings [Text Block] | | Top Ten Holdings (as a % of Net Assets) as of 10/31/2024 State of California Current Refunding GO 7.3% California Infrastructure & Economic Development Bank Current Refunding Revenue Bonds, Series A 5.1% San Francisco City & County Airport Comm-San Francisco International Airport Current Refunding Revenue Bonds, Series A 5.1% State of California Water Utility Improvements GO 4.4% San Francisco City & County Airport Comm-San Francisco International Airport Current Refunding Revenue Bonds, Series C 3.4% California Educational Facilities Authority University & College Improvements Revenue Bonds, Series V-3 3.2% University of California Current Refunding Revenue Bonds, Series BN 3.1% Los Angeles Department of Water & Power Water System Revenue Bonds, Series A 2.8% City & County of San Francisco Current Refunding GO, Series R1 2.8% County of Santa Clara GO, Series C 2.8% | |
| Material Fund Change [Text Block] | | | |
| Updated Prospectus Phone Number | | (800) 607-2200 | |
| Updated Prospectus Web Address | | www.oldwestburyfunds.com</span>" id="sjs-C60"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: left;">www.oldwestburyfunds.com</span> | |
| C000221944 | | | |
| Shareholder Report [Line Items] | | | |
| Fund Name | | Credit Income Fund | |
| Trading Symbol | | OWCIX | |
| Annual or Semi-Annual Statement [Text Block] | | This annual shareholder report contains important information about the Old Westbury Credit Income Fund (the "Fund") for the period of November 1, 2023 to October 31, 2024 (the "reporting period"). | |
| Shareholder Report Annual or Semi-Annual | | Annual Shareholder Report | |
| Additional Information [Text Block] | | You can find additional information about the Fund at www.oldwestburyfunds.com | |
| Additional Information Phone Number | | (800) 607-2200 | |
| Additional Information Website | | www.oldwestburyfunds.com</span>" id="sjs-C69"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: justify;">www.oldwestburyfunds.com</span> | |
| Expenses [Text Block] | | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Old Westbury Credit Income Fund $91 0.85% | |
| Expenses Paid, Amount | | $ 91 | |
| Expense Ratio, Percent | | 0.85% | |
| Factors Affecting Performance [Text Block] | | What drove Fund performance during the past 12 months? The U.S. fixed income market generally enjoyed strong performance in the reporting period, as inflation continued to subside and the U.S. Federal Reserve paused interest rate hiking and finally began recalibrating the interest rates. The U.S. economy remained resilient with the labor market exhibiting decent fundamentals and normalizing to trend. Less volatile macroeconomic data along with interest rate policy supported fixed income spreads as default levels remained low, consumer balance sheets were healthy, and market liquidity contained. What contributed to performance? Performance of the Fund’s primary benchmark is provided in the table below. Here, we discuss the Fund’s performance against its secondary benchmark, the ICE BofA 1-10 Year U.S. Corporate Index. The Fund benefited from steady interest rates for the better part of the reporting period. This interest rate environment helped reduce overall fixed income market volatility relative to prior years. At the same time, inflation continued to decline. The U.S. labor market maintained its resilience, which helped support overall growth and therefore overall company earnings and household balance sheets, which contributed to performance of the Fund. This backdrop increased confidence that the U.S. would be able to avoid a recession, which helped fixed income assets with decent, and even somewhat overvalued, spread levels continue to generate excess returns, which contributed to performance of the Fund. What detracted from performance? Even with the U.S. Federal Reserve holding interest rates steady and ultimately beginning to adjust them downward, the shape of the yield curve remained quite flat. A flat yield curve does not support roll yield — that is, the potential to earn extra returns as a bond approaches its maturity date and its yield declines, which typically occurs with normal or steeper yield curves. Given the Fund’s barbell approach to portfolio construction, a flat yield curve reduced the benefits of roll yield and removed a key source of return from positioning in longer-dated Treasury securities, which detracted from performance of the Fund. | |
| Line Graph [Table Text Block] | | Old Westbury Credit Income Fund ICE BofA U.S. Broad Market Index ICE BofA 1-10 Year U.S. Corporate Index 10/01/2020 $10,000 $10,000 $10,000 2020 $9,990 $9,950 $10,006 2021 $10,580 $9,893 $10,107 2022 $8,697 $8,331 $8,837 2023 $8,606 $8,369 $9,205 2024 $9,761 $9,252 $10,222 | |
| Average Annual Return [Table Text Block] | | Fund 1 Year Since Inception
(October 1, 2020) Old Westbury Credit Income Fund 13.42% - ICE BofA U.S. Broad Market Index 10.55% - ICE BofA 1-10 Year U.S. Corporate Index 11.05% 0.55% | |
| Performance Inception Date | | | Oct. 01, 2020 |
| AssetsNet | $ 2,379,934,982 | $ 2,379,934,982 | $ 2,379,934,982 |
| Holdings Count | Holding | 758 | 758 | 758 |
| Advisory Fees Paid, Amount | | $ 13,876,765 | |
| InvestmentCompanyPortfolioTurnover | | 20% | |
| Additional Fund Statistics [Text Block] | | Fund Statistics as of 10/31/2024 Total Net Assets $2,379,934,982 # of Portfolio Holdings 758 Portfolio Turnover Rate 20% Total Advisory Fees Paid (Net of Waivers) $13,876,765 | |
| Holdings [Text Block] | | Asset Allocations (as a % of Net Assets) as of 10/31/2024 U.S. Government Agencies and Securities 33.8% Non-Agency Mortgage-Backed Securities 23.6% Asset-Backed Securities 17.6% Exchange-Traded Funds 16.5% Corporate Bonds 5.6% Preferred Stocks 0.2% U.S. Government Sponsored Agency Mortgage-Backed Securities 0.2% Other Assets and Liabilities 2.5% | |
| Largest Holdings [Text Block] | | Top Ten Holdings (as a % of Net Assets) as of 10/31/2024 U.S. Treasury Bonds 25.2% U.S. Treasury Notes 8.6% iShares JP Morgan USD Emerging Markets Bond ETF 7.9% Ajax Mortgage Loan Trust 4.1% SPDR Bloomberg Convertible Securities ETF 3.6% iShares MBS ETF 3.2% Barclays Mortgage Loan Trust 3.0% Invesco Preferred ETF 1.8% Progress Residential Trust 1.8% Countrywide Alternative Loan Trust 1.6% | |
| Material Fund Change [Text Block] | | | |
| Updated Prospectus Phone Number | | (800) 607-2200 | |
| Updated Prospectus Web Address | | www.oldwestburyfunds.com</span>" id="sjs-C86"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: left;">www.oldwestburyfunds.com</span> | |
| C000004833 | | | |
| Shareholder Report [Line Items] | | | |
| Fund Name | | Fixed Income Fund | |
| Trading Symbol | | OWFIX | |
| Annual or Semi-Annual Statement [Text Block] | | This annual shareholder report contains important information about the Old Westbury Fixed Income Fund (the "Fund") for the period of November 1, 2023 to October 31, 2024 (the "reporting period"). | |
| Shareholder Report Annual or Semi-Annual | | Annual Shareholder Report | |
| Additional Information [Text Block] | | You can find additional information about the Fund at www.oldwestburyfunds.com | |
| Additional Information Phone Number | | (800) 607-2200 | |
| Additional Information Website | | www.oldwestburyfunds.com</span>" id="sjs-C95"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: justify;">www.oldwestburyfunds.com</span> | |
| Expenses [Text Block] | | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Old Westbury Fixed Income Fund $59 0.57% | |
| Expenses Paid, Amount | | $ 59 | |
| Expense Ratio, Percent | | 0.57% | |
| Factors Affecting Performance [Text Block] | | What drove Fund performance during the past 12 months? Yields on U.S. Treasury securities declined across all maturities in response to moderating inflation and expectations that the U.S. Federal Reserve would soon begin to lower interest rates. Credit spreads tightened throughout the reporting period as a stronger-than-expected U.S. economy, combined with lower inflation, buoyed credit fundamentals. Demand for fixed income assets was strong throughout the reporting period as investors were attracted to the relatively high yields; strong demand was supportive of fixed-income securities’ prices. What contributed to performance? Performance of the Fund’s primary benchmark is provided in the table below. Here, we discuss the Fund’s performance against its secondary benchmark, the ICE BofA 1-10 Year AAA-A U.S. Corporate & Government Index. Relative to the Fund’s secondary benchmark, the Fund was overweight duration during the reporting period. Duration is a measure of portfolio’s price sensitivity to interest rate moves. As interest rates declined, the Fund’s overweight position also contributed to its performance. Asset allocation also contributed to performance, as credit spreads tightened for investment-grade corporate bonds and structured products. The Fund’s slight overweight position in corporate bonds and its out-of-benchmark exposure to asset-backed securities and collateralized loan obligations contributed to performance. What detracted from performance? During the reporting period, the move to lower interest rates was led by securities with maturities between 2 and 3 years. Relative to the Fund’s secondary benchmark, the Fund was underweight shorter-dated securities and was overweight securities with maturities beyond 10 years. That positioning detracted from performance. | |
| Line Graph [Table Text Block] | | Old Westbury Fixed Income Fund ICE BofA U.S. Broad Market Index ICE BofA 1-10 Year AAA-A U.S. Corporate & Government Index 2014 $10,000 $10,000 $10,000 2015 $10,105 $10,207 $10,213 2016 $10,315 $10,653 $10,487 2017 $10,306 $10,750 $10,507 2018 $10,154 $10,534 $10,409 2019 $11,008 $11,768 $11,256 2020 $11,584 $12,501 $11,869 2021 $11,442 $12,431 $11,735 2022 $10,253 $10,468 $10,630 2023 $10,374 $10,515 $10,831 2024 $11,210 $11,625 $11,655 | |
| Average Annual Return [Table Text Block] | | Fund 1 Year 5 Years 10 Years Old Westbury Fixed Income Fund 8.06% 0.36% 1.15% ICE BofA U.S. Broad Market Index 10.55% - 1.52% ICE BofA 1-10 Year AAA-A U.S. Corporate & Government Index 7.61% 0.70% 1.54% | |
| AssetsNet | $ 1,389,484,353 | $ 1,389,484,353 | $ 1,389,484,353 |
| Holdings Count | Holding | 145 | 145 | 145 |
| Advisory Fees Paid, Amount | | $ 4,042,194 | |
| InvestmentCompanyPortfolioTurnover | | 102% | |
| Additional Fund Statistics [Text Block] | | Fund Statistics as of 10/31/2024 Total Net Assets $1,389,484,353 # of Portfolio Holdings 145 Portfolio Turnover Rate 102% Total Advisory Fees Paid (Net of Waivers) $4,042,194 | |
| Holdings [Text Block] | | Asset Allocations (as a % of Net Assets) as of 10/31/2024 U.S. Government Agencies and Securities 65.6% Corporate Bonds 24.7% Asset-Backed Securities 7.8% Other Assets and Liabilities 1.9% | |
| Largest Holdings [Text Block] | | Top Ten Holdings (as a % of Net Assets) as of 10/31/2024 U.S. Treasury Notes 57.4% U.S. Treasury Bonds 4.5% U.S. Treasury Inflation Indexed Notes 2.6% JPMorgan Chase & Co. 0.9% CarMax Auto Owner Trust 0.7% U.S. Treasury Bills 0.7% Bank of America Corp. 0.6% Capital One Financial Corp. 0.5% BP Capital Markets America, Inc. 0.5% General Motors Financial Co., Inc. 0.5% | |
| Material Fund Change [Text Block] | | | |
| Updated Prospectus Phone Number | | (800) 607-2200 | |
| Updated Prospectus Web Address | | www.oldwestburyfunds.com</span>" id="sjs-C111"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: left;">www.oldwestburyfunds.com</span> | |
| C000004835 | | | |
| Shareholder Report [Line Items] | | | |
| Fund Name | | Large Cap Strategies Fund | |
| Trading Symbol | | OWLSX | |
| Annual or Semi-Annual Statement [Text Block] | | This annual shareholder report contains important information about the Old Westbury Large Cap Strategies Fund (the "Fund") for the period of November 1, 2023 to October 31, 2024 (the "reporting period"). | |
| Shareholder Report Annual or Semi-Annual | | Annual Shareholder Report | |
| Additional Information [Text Block] | | You can find additional information about the Fund at www.oldwestburyfunds.com | |
| Additional Information Phone Number | | (800) 607-2200 | |
| Additional Information Website | | www.oldwestburyfunds.com</span>" id="sjs-C120"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: justify;">www.oldwestburyfunds.com</span> | |
| Expenses [Text Block] | | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Old Westbury Large Cap Strategies Fund $128 1.09% | |
| Expenses Paid, Amount | | $ 128 | |
| Expense Ratio, Percent | | 1.09% | |
| Factors Affecting Performance [Text Block] | | What drove Fund performance during the past 12 months? Technology and financials were the market’s strongest performing sectors during the reporting period. Global growth stocks outperformed value during the reporting period. U.S. markets significantly outperformed emerging markets, which in turn led developed-international markets. What contributed to performance? Performance of the Fund’s primary benchmark is provided in the table below. Here, we discuss the Fund’s performance against its secondary benchmark, MSCI ACWI Large Cap Index (Net). The Fund delivered strong gains during the reporting period. The Fund benefited from exposure to the artificial intelligence and semiconductor theme through U.S. positions in chip manufacturer NVIDIA and semiconductor solutions business Broadcom. Stock selection in the technology and industrials sectors also contributed to the Fund’s performance. From a regional perspective, strong stock selection in the U.S. and developed Europe benefited the Fund as well. What detracted from performance? Despite portfolio gains, a few areas detracted from performance during the reporting period. Baillie Gifford Overseas Limited’s dedicated China strategy, which was terminated on February 6, 2024, was a top detractor from the Fund's performance compared to its secondary benchmark. Underweight positions to top performing benchmark names, such as Taiwanese chip manufacturer TSMC, U.S. consumer electronics business Apple, and U.S. software company Alphabet Class A, hurt performance. Stock selection in the materials and health care sectors also detracted from performance. On a regional basis, weak stock selection in emerging Asia Pacific and Asia Pacific ex-Japan hurt performance. | |
| Line Graph [Table Text Block] | | Old Westbury Large Cap Strategies Fund MSCI ACWI Investable Market Index (Net) MSCI ACWI Large Cap Index (Net) 2014 $10,000 $10,000 $10,000 2015 $10,201 $10,010 $9,963 2016 $10,397 $10,244 $10,163 2017 $12,136 $12,653 $12,548 2018 $12,008 $12,533 $12,562 2019 $13,559 $14,038 $14,153 2020 $14,506 $14,644 $14,956 2021 $19,386 $20,236 $20,465 2022 $14,777 $16,145 $16,480 2023 $15,872 $17,667 $18,434 2024 $21,395 $23,379 $24,598 | |
| Average Annual Return [Table Text Block] | | Fund 1 Year 5 Years 10 Years Old Westbury Large Cap Strategies Fund 34.80% 9.55% 7.90% MSCI ACWI Investable Market Index (Net) 32.33% 10.74% 8.86% MSCI ACWI Large Cap Index (Net) 33.44% 11.69% 9.42% | |
| AssetsNet | $ 24,640,062,935 | $ 24,640,062,935 | $ 24,640,062,935 |
| Holdings Count | Holding | 629 | 629 | 629 |
| Advisory Fees Paid, Amount | | $ 188,496,766 | |
| InvestmentCompanyPortfolioTurnover | | 37% | |
| Additional Fund Statistics [Text Block] | | Fund Statistics as of 10/31/2024 Total Net Assets $24,640,062,935 # of Portfolio Holdings 629 Portfolio Turnover Rate 37% Total Advisory Fees Paid (Net of Waivers) $188,496,766 | |
| Holdings [Text Block] | | Sector Weightings (as a % of Net Assets) as of 10/31/2024 Information Technology 25.3% Consumer Discretionary 11.2% Industrials 11.2% Health Care 10.2% Communication Services 8.3% Financial Services 7.7% Banks 6.3% Consumer Staples 6.1% Other Sectors 12.2% Other Assets and Liabilities 1.5% | |
| Largest Holdings [Text Block] | | Top Ten Holdings (as a % of Net Assets) as of 10/31/2024 NVIDIA Corp. 5.4% Microsoft Corp. 5.1% Apple, Inc. 4.6% Amazon.com, Inc. 3.1% Alphabet, Inc. 3.0% Broadcom, Inc. 2.3% JPMorgan Chase & Co. 2.2% Meta Platforms, Inc. 2.2% UnitedHealth Group, Inc. 1.5% Oracle Corp. 1.3% | |
| Material Fund Change [Text Block] | | Material Fund Changes This is a summary of certain changes to the Fund for the reporting period. For more complete information, you may review the Fund's next prospectus, which we expect to be available by March 1, 2025 at www.oldwestburyfunds.com Effective February 6, 2024, (i) Aikya Investment Management Limited serves as a sub-adviser to the Fund, and (ii) Baillie Gifford Overseas Limited no longer serves as sub-adviser to the Fund. The Fund removed “Growth Style Investment Risk” and “Value Style Investment Risk” disclosure from its Prospectus’ Principal Risks in connection with these changes. | |
| Updated Prospectus Phone Number | | (800) 607-2200 | |
| Updated Prospectus Web Address | | www.oldwestburyfunds.com</span>" id="sjs-C136"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: left;">www.oldwestburyfunds.com</span> | |
| C000004838 | | | |
| Shareholder Report [Line Items] | | | |
| Fund Name | | Municipal Bond Fund | |
| Trading Symbol | | OWMBX | |
| Annual or Semi-Annual Statement [Text Block] | | This annual shareholder report contains important information about the Old Westbury Municipal Bond Fund (the "Fund") for the period of November 1, 2023 to October 31, 2024 (the "reporting period"). | |
| Shareholder Report Annual or Semi-Annual | | Annual Shareholder Report | |
| Additional Information [Text Block] | | You can find additional information about the Fund at www.oldwestburyfunds.com | |
| Additional Information Phone Number | | (800) 607-2200 | |
| Additional Information Website | | www.oldwestburyfunds.com</span>" id="sjs-C145"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: justify;">www.oldwestburyfunds.com</span> | |
| Expenses [Text Block] | | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Old Westbury Municipal Bond Fund $59 0.57% | |
| Expenses Paid, Amount | | $ 59 | |
| Expense Ratio, Percent | | 0.57% | |
| Factors Affecting Performance [Text Block] | | What drove Fund performance during the past 12 months? Throughout the reporting period, U.S. fixed income market performance was driven by an evolution in U.S. Federal Reserve policy from interest rate increases to interest rate cuts, heightened investor demand for bonds amid economic uncertainty, and market volatility influenced by fluctuating economic indicators and the presidential election. In the municipal bond market, supply and demand garnered much of investors’ focus. Supply surprised significantly to the upside after two years of paltry issuance as issuers looked to front-run election-related volatility, while demand surged as investors looked to capitalize upon particularly attractive tax-exempt yields. What contributed to performance? The above dynamics led to a continued longer duration posture relative to the Fund’s secondary benchmark, the ICE BofA 1-12 Year AAA-AA Municipal Securities Index, which contributed notably to performance during the reporting period. Performance of the Fund’s primary benchmark is provided in the table below.Here, we discuss the Fund’s performance against its secondary benchmark, the ICE BofA 1-12 Year AAA-AA Municipal Securities Index. Throughout the reporting period, the Fund maintained a longer duration posture compared to its secondary benchmark, reflective of strong municipal fundamentals, a favorable supply/demand mix, attractive tax-adjusted yields, and a high-tax environment conducive to elevated demand for the asset class. Despite broad market volatility, particularly in the run-up to the presidential election, the investment team’s investment thesis remained unchanged: the belief that ultimately, the aggressive U.S. Federal Reserve interest rate hiking cycle would result in lower inflation and slower domestic growth, driving higher demand for municipals with yields at some of the most attractive levels in the past 20 years. As a result, the longer-duration posture of the Fund contributed significantly to performance, as did credit spread management (spreads compressed as demand for higher-quality municipals increased) and roll down (driven by a steeper curve slope in the intermediate part of the municipal yield curve). What detracted from performance? Despite the stronger gains, certain challenges inhibited broader outperformance compared to its secondary benchmark. In particular, the credit rating profile of the Fund’s portfolio holdings (overweights to AAA and A credits, funded by an underweight to AA credits) created a slight performance drag as longer-dated AA spreads compressed more than comparable-maturity A spreads, which detracted from performance. | |
| Line Graph [Table Text Block] | | Old Westbury Municipal Bond Fund ICE BofA U.S. Municipal Securities Index ICE BofA 1-12 Year AAA-AA Municipal Securities Index 2014 $10,000 $10,000 $10,000 2015 $10,151 $10,297 $10,196 2016 $10,359 $10,754 $10,409 2017 $10,405 $10,981 $10,533 2018 $10,267 $10,907 $10,447 2019 $10,978 $11,960 $11,158 2020 $11,349 $12,378 $11,557 2021 $11,344 $12,762 $11,629 2022 $10,426 $11,167 $10,805 2023 $10,566 $11,452 $11,005 2024 $11,236 $12,634 $11,681 | |
| Average Annual Return [Table Text Block] | | Fund 1 Year 5 Years 10 Years Old Westbury Municipal Bond Fund 6.35% 0.47% 1.17% ICE BofA U.S. Municipal Securities Index 10.33% 1.10% 2.37% ICE BofA 1-12 Year AAA-AA Municipal Securities Index 6.15% 0.92% 1.57% | |
| AssetsNet | $ 4,146,321,857 | $ 4,146,321,857 | $ 4,146,321,857 |
| Holdings Count | Holding | 571 | 571 | 571 |
| Advisory Fees Paid, Amount | | $ 11,865,624 | |
| InvestmentCompanyPortfolioTurnover | | 39% | |
| Additional Fund Statistics [Text Block] | | Fund Statistics as of 10/31/2024 Total Net Assets $4,146,321,857 # of Portfolio Holdings 571 Portfolio Turnover Rate 39% Total Advisory Fees Paid (Net of Waivers) $11,865,624 | |
| Holdings [Text Block] | | State Diversification (as a % of Net Assets) as of 10/31/2024 Texas 19.6% New York 11.3% California 6.0% Washington 5.8% New Jersey 5.6% Massachusetts 5.1% Maryland 4.6% Colorado 2.8% Other States 35.1% Other Assets and Liabilities 4.1% | |
| Largest Holdings [Text Block] | | Top Ten Holdings (as a % of Net Assets) as of 10/31/2024 New York City Transitional Finance Authority Future Tax Secured Revenue Bonds, Sub-Series D-2 1.6% Texas Tech University System University & College Improvements Revenue Bonds, Series A 1.5% Texas State University System University & College Improvements Revenue Bonds 1.5% State of Maryland School Improvements GO, Series A 1.3% State of California Current Refunding GO 1.4% Utility Debt Securitization Authority Refunding Revenue Bonds, Series TE 1.4% Board of Regents of the University of Texas System Current Refunding Revenue Bonds, Series A 1.3% U.S. Treasury Notes 1.2% Empire State Development Corp. Correctional Facilities Improvements Revenue Bonds 1.2% County of Collin Public Facilities GO 1.2% | |
| Material Fund Change [Text Block] | | | |
| Updated Prospectus Phone Number | | (800) 607-2200 | |
| Updated Prospectus Web Address | | www.oldwestburyfunds.com</span>" id="sjs-C161"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: left;">www.oldwestburyfunds.com</span> | |
| C000206043 | | | |
| Shareholder Report [Line Items] | | | |
| Fund Name | | New York Municipal Bond Fund | |
| Trading Symbol | | OWNYX | |
| Annual or Semi-Annual Statement [Text Block] | | This annual shareholder report contains important information about the Old Westbury New York Municipal Bond Fund (the "Fund") for the period of November 1, 2023 to October 31, 2024 (the "reporting period"). | |
| Shareholder Report Annual or Semi-Annual | | Annual Shareholder Report | |
| Additional Information [Text Block] | | You can find additional information about the Fund at www.oldwestburyfunds.com | |
| Additional Information Phone Number | | (800) 607-2200 | |
| Additional Information Website | | www.oldwestburyfunds.com</span>" id="sjs-C170"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: justify;">www.oldwestburyfunds.com</span> | |
| Expenses [Text Block] | | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Old Westbury New York Municipal Bond Fund $59 0.57% | |
| Expenses Paid, Amount | | $ 59 | |
| Expense Ratio, Percent | | 0.57% | |
| Factors Affecting Performance [Text Block] | | What drove Fund performance during the past 12 months? Throughout the reporting period, U.S. fixed income market performance was driven by an evolution in U.S. Federal Reserve policy from interest rate increases to interest rate cuts, heightened investor demand for bonds amid economic uncertainty, and market volatility influenced by fluctuating economic indicators and the presidential election. In the municipal bond market, supply and demand garnered much of investors’ focus. Supply rather significantly to the upside after two years of paltry issuance as issuers looked to front-run election-related volatility, while demand surged as investors looked to capitalize upon particularly attractive tax-exempt yields. New York credits experienced very strong demand throughout the reporting period given the onerous tax burden in the state; in particular, smaller/more unique issuers tended to price at tighter spreads than more generic issuers, and despite the embedded premium, were generally well-oversubscribed given the inherent value of the tax exemption for residents of the state. What contributed to performance? Performance of the Fund’s primary benchmark is provided in the table below. Here, we discuss the Fund’s performance against its secondary benchmark, the ICE BofA 3-7 Year AAA-AA Municipal Securities Index. Throughout the reporting period, the Fund maintained a longer duration posture compared to its secondary benchmark, reflective of strong municipal fundamentals, a favorable supply/demand mix, attractive tax-adjusted yields, and a high-tax environment conducive to elevated demand for the asset class. Despite broad market volatility, particularly in the run-up to the presidential election, the investment team’s investment thesis remained unchanged: the belief that ultimately, the aggressive U.S. Federal Reserve interest rate hiking cycle would result in lower inflation and slower domestic growth, driving higher demand for municipals with yields at some of the most attractive levels in the past 20 years. As a result, the longer-duration posture of the Fund was the top contributor to performance. What detracted from performance? Despite the stronger gains, certain headwinds did inhibit broader outperformance. In particular, the credit rating profile of the Fund's portfolio holdings (overweights to AAA and A credits, funded by an underweight to AA credits) created a slight performance drag as AA spreads in the intermediate part of the yield curve compressed more than comparable-maturity A spreads, which detracted from performance. | |
| Line Graph [Table Text Block] | | Old Westbury New York Municipal Bond Fund ICE BofA U.S. Municipal Securities Index ICE BofA 3-7 Year AAA-AA Municipal Securities Index 12/04/2018 $10,000 $10,000 $10,000 2019 $10,536 $10,841 $10,550 2020 $10,819 $11,221 $10,957 2021 $10,879 $11,569 $10,993 2022 $10,039 $10,122 $10,149 2023 $10,197 $10,381 $10,312 2024 $10,833 $11,453 $10,966 | |
| Average Annual Return [Table Text Block] | | Fund 1 Year 5 Years Since Inception
(December 4, 2018) Old Westbury New York Municipal Bond Fund 6.24% 0.56% 1.36% ICE BofA U.S. Municipal Securities Index 10.33% 1.10% 2.32% ICE BofA 3-7 Year AAA-AA Municipal Securities Index 6.35% 0.78% 1.57% | |
| Performance Inception Date | | | Dec. 04, 2018 |
| AssetsNet | $ 580,149,881 | $ 580,149,881 | $ 580,149,881 |
| Holdings Count | Holding | 164 | 164 | 164 |
| Advisory Fees Paid, Amount | | $ 1,559,080 | |
| InvestmentCompanyPortfolioTurnover | | 32% | |
| Additional Fund Statistics [Text Block] | | Fund Statistics as of 10/31/2024 Total Net Assets $580,149,881 # of Portfolio Holdings 164 Portfolio Turnover Rate 32% Total Advisory Fees Paid (Net of Waivers) $1,559,080 | |
| Holdings [Text Block] | | State Diversification (as a % of Net Assets) as of 10/31/2024 New York 90.0% Other Assets and Liabilities 10.0% | |
| Largest Holdings [Text Block] | | Top Ten Holdings (as a % of Net Assets) as of 10/31/2024 County of Westchester NY Recreation Facilities Improvements GO, Series A 5.8% Utility Debt Securitization Authority Refunding Revenue Bonds, Series TE 5.5% U.S. Treasury Notes 5.4% New York Power Authority Electric Light & Power Improvements Revenue Bonds, Series A 4.0% New York State Dormitory Authority University & College Improvements Revenue Bonds, Series A 3.7% New York City Transitional Finance Authority Future Tax Secured Current Refunding Revenue Bonds 3.4% Nassau County Interim Finance Authority Cash Flow Management Revenue Bonds, Series A 3.3% New York State Environmental Facilities Corp. Water Utility Improvements Revenue Bonds 3.4% New York State Dormitory Authority Cash Flow Management Revenue Bonds, Series B 2.8% New York State Dormitory Authority Refunding Revenue Bonds, Series A 2.7% | |
| Material Fund Change [Text Block] | | | |
| Updated Prospectus Phone Number | | (800) 607-2200 | |
| Updated Prospectus Web Address | | www.oldwestburyfunds.com</span>" id="sjs-C187"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: left;">www.oldwestburyfunds.com</span> | |
| C000248048 | | | |
| Shareholder Report [Line Items] | | | |
| Fund Name | Short-Term Bond Fund | | |
| Trading Symbol | OWSBX | | |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about the Old Westbury Short-Term Bond Fund (the "Fund") for the period of February 29, 2024, the Fund's Inception, to October 31, 2024 (the "reporting period"). | | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | | |
| Additional Information [Text Block] | You can find additional information about the Fund at www.oldwestburyfunds.com | | |
| Additional Information Phone Number | (800) 607-2200 | | |
| Additional Information Website | www.oldwestburyfunds.com</span>" id="sjs-B196"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: justify;">www.oldwestburyfunds.com</span> | | |
| Expenses [Text Block] | What were the Fund costs for the reporting period? (based on a hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Old Westbury Short-Term Bond Fund $25 0.37% | | |
| Expenses Paid, Amount | $ 25 | | |
| Expense Ratio, Percent | 0.37% | | |
| Factors Affecting Performance [Text Block] | What drove Fund performance during the past 12 months? Yields at the front of the yield curve declined since the Fund’s February 29, 2024, inception as the U.S. Federal Reserve began lowering interest rates. Credit spreads tightened and risk assets outperformed U.S. Treasuries as economic growth continued at a healthy pace. Investment-grade bond funds have seen increased inflows, driven by the appeal of higher yields currently available in the market. What contributed to performance? Performance of the Fund’s primary benchmark is provided in the table below. Here, we discuss the Fund’s performance against its secondary benchmark, the ICE BofA 1-3 Year AAA-A U.S. Corporate & Government Index. Credit performed well during the reporting period as economic data remained resilient, inflation continued to decline, and market fears of a recession diminished. This led credit spreads to tighten across the investment-grade market and credit to outperform U.S. Treasuries. The Fund’s overweight to corporate bonds and asset-backed securities aided performance. Additionally, the Fund was positioned to seek a higher yield than its secondary benchmark, which also enhanced performance. What detracted from performance? Interest rates on U.S. Treasury notes maturing within 5 years fell since the Fund’s inception as the U.S. Federal Reserve lowered the federal funds rate by 50 basis points in September and signaled additional easing. While overall duration exposure was neutral to performance, the front of the yield curve steepened as interest rates within 2 years fell further than longer-dated yields, which detracted from performance. The Fund’s overweight to bonds with 3- and 5-year maturities also detracted from performance. | | |
| Line Graph [Table Text Block] | Old Westbury Short-Term Bond Fund ICE BofA U.S. Broad Market Index ICE BofA 1-3 Year AAA-A U.S. Corporate & Government Index 02/29/2024 $10,000 $10,000 $10,000 03/31/2024 $10,040 $10,084 $10,036 04/30/2024 $10,000 $9,841 $10,005 05/31/2024 $10,080 $10,008 $10,076 06/30/2024 $10,140 $10,103 $10,132 07/31/2024 $10,251 $10,337 $10,250 08/31/2024 $10,343 $10,485 $10,343 09/30/2024 $10,430 $10,625 $10,428 10/31/2024 $10,369 $10,365 $10,369 | | |
| Average Annual Return [Table Text Block] | Fund Since Inception
(February 29, 2024) Old Westbury Short-Term Bond Fund 3.69% ICE BofA U.S. Broad Market Index 3.65% ICE BofA 1-3 Year AAA-A U.S. Corporate & Government Index 3.69% | | |
| Performance Inception Date | | | Feb. 29, 2024 |
| AssetsNet | $ 60,071,688 | $ 60,071,688 | $ 60,071,688 |
| Holdings Count | Holding | 98 | 98 | 98 |
| Advisory Fees Paid, Amount | $ 0 | | |
| InvestmentCompanyPortfolioTurnover | 13% | | |
| Additional Fund Statistics [Text Block] | Fund Statistics as of 10/31/2024 Total Net Assets $60,071,688 # of Portfolio Holdings 98 Portfolio Turnover Rate 13% Total Advisory Fees Paid (Net of Waivers) $0 | | |
| Holdings [Text Block] | Asset Allocations (as a % of Net Assets) as of 10/31/2024 U.S. Government Agencies and Securities 56.3% Corporate Bonds 35.5% Asset-Backed Securities 6.9% Other Assets and Liabilities 1.3% | | |
| Largest Holdings [Text Block] | Top Ten Holdings (as a % of Net Assets) as of 10/31/2024 U.S. Treasury Notes 45.8% U.S. Treasury Bills 10.5% DTE Energy Co. 1.6% AerCap Ireland Capital DAC/AerCap Global Aviation Trust 1.6% Sumitomo Mitsui Financial Group, Inc. 1.5% Broadcom, Inc. 1.5% General Motors Financial Co., Inc. 1.5% NextEra Energy Capital Holdings, Inc. 1.4% Air Lease Corp. 1.2% Equinix, Inc. 1.2% | | |
| Material Fund Change [Text Block] | | | |
| Updated Prospectus Phone Number | (800) 607-2200 | | |
| Updated Prospectus Web Address | www.oldwestburyfunds.com</span>" id="sjs-B213"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: left;">www.oldwestburyfunds.com</span> | | |
| C000004834 | | | |
| Shareholder Report [Line Items] | | | |
| Fund Name | | Small & Mid Cap Strategies Fund | |
| Trading Symbol | | OWSMX | |
| Annual or Semi-Annual Statement [Text Block] | | This annual shareholder report contains important information about the Old Westbury Small & Mid Cap Strategies Fund (the "Fund") for the period of November 1, 2023 to October 31, 2024 (the "reporting period"). | |
| Shareholder Report Annual or Semi-Annual | | Annual Shareholder Report | |
| Additional Information [Text Block] | | You can find additional information about the Fund at www.oldwestburyfunds.com | |
| Additional Information Phone Number | | (800) 607-2200 | |
| Additional Information Website | | www.oldwestburyfunds.com</span>" id="sjs-C222"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: justify;">www.oldwestburyfunds.com</span> | |
| Expenses [Text Block] | | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Fund Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Old Westbury Small & Mid Cap Strategies Fund $124 1.10% | |
| Expenses Paid, Amount | | $ 124 | |
| Expense Ratio, Percent | | 1.10% | |
| Factors Affecting Performance [Text Block] | | What drove Fund performance during the past 12 months? Industrials and financials were the market’s strongest performing sectors during the reporting period. Global small-to-mid-cap growth stocks narrowly outperformed value during the reporting period. The U.S outperformed developed-international markets, which in turn led emerging markets. What contributed to performance? Performance of the Fund’s primary benchmark is provided in the table below. Here, we discuss the Fund’s performance against its secondary benchmark, the MSCI ACWI SMID Cap Index (Net). The Fund delivered strong gains during the reporting period due largely to strong performance from the Fund’s small capitalization holdings. Stock selection in the materials and financials sectors also contributed to the Fund’s performance. In terms of sub-industries, health care and industrial equipment companies, specifically U.S. medical device company Globus Medical, also contributed to performance. From a regional perspective, strong stock selection in Japan and developed Europe benefited the Fund. What detracted from performance? The Fund faced several challenges in the reporting period. Baillie Gifford Overseas Limited’s international strategy, which was terminated on July 16, 2024, was a top detractor for the Fund. In addition, no exposure or an underweight position to strong performers, including U.S. software company Fair Isaac, in the Fund’s secondary benchmark, detracted from performance. Stock selection in the technology and energy sectors also detracted from performance. On a regional basis, weak stock selection in the U.S. and Israel hurt performance. | |
| Line Graph [Table Text Block] | | Old Westbury Small & Mid Cap Strategies Fund MSCI ACWI Investable Market Index (Net) MSCI ACWI SMID Cap Index (Net) 2014 $10,000 $10,000 $10,000 2015 $10,289 $10,010 $10,130 2016 $10,817 $10,244 $10,451 2017 $12,726 $12,653 $12,925 2018 $12,393 $12,533 $12,446 2019 $13,563 $14,038 $13,721 2020 $14,365 $14,644 $13,805 2021 $18,979 $20,236 $19,616 2022 $13,778 $16,145 $15,252 2023 $13,705 $17,667 $15,599 2024 $17,304 $23,379 $20,125 | |
| Average Annual Return [Table Text Block] | | Fund 1 Year 5 Years 10 Years Old Westbury Small & Mid Cap Strategies Fund 26.26% 4.99% 5.64% MSCI ACWI Investable Market Index (Net) 32.33% 10.74% 8.86% MSCI ACWI SMID Cap Index (Net) 29.01% 7.96% 7.24% | |
| AssetsNet | $ 8,841,523,403 | $ 8,841,523,403 | $ 8,841,523,403 |
| Holdings Count | Holding | 2,461 | 2,461 | 2,461 |
| Advisory Fees Paid, Amount | | $ 68,130,297 | |
| InvestmentCompanyPortfolioTurnover | | 62% | |
| Additional Fund Statistics [Text Block] | | Fund Statistics as of 10/31/2024 Total Net Assets $8,841,523,403 # of Portfolio Holdings 2,461 Portfolio Turnover Rate 62% Total Advisory Fees Paid (Net of Waivers) $68,130,297 | |
| Holdings [Text Block] | | Country Weightings (as a % of Net Assets) as of 10/31/2024 United States 49.5% Japan 8.7% China 4.4% United Kingdom 4.3% Canada 2.4% Australia 2.2% Israel 1.9% Other Countries 15.8% Other Assets and Liabilities 10.8% | |
| Largest Holdings [Text Block] | | Top Ten Holdings (as a % of Net Assets) as of 10/31/2024 Utilities Select Sector SPDR Fund 4.8% VanEck Junior Gold Miners ETF 1.7% SPDR S&P Biotech ETF 1.0% Saia, Inc. 0.8% Dollarama, Inc. 0.8% SPDR S&P Regional Banking ETF 0.7% Booz Allen Hamilton Holding Corp. 0.7% BJ's Wholesale Club Holdings, Inc. 0.7% Clean Harbors, Inc. 0.6% Nice Ltd. 0.6% | |
| Material Fund Change [Text Block] | | Material Fund Changes This is a summary of certain changes to the Fund for the reporting period. For more complete information, you may review the Fund's next prospectus, which we expect to be available by March 1, 2025 at www.oldwestburyfunds.com Effective July 16, 2024, Baillie Gifford Overseas Limited no longer serves as sub-adviser to the Fund. | |
| Updated Prospectus Phone Number | | (800) 607-2200 | |
| Updated Prospectus Web Address | | www.oldwestburyfunds.com</span>" id="sjs-C238"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 14.4px; margin: 0px; overflow: visible; text-align: left;">www.oldwestburyfunds.com</span> | |
