Vanguard Market Neutral Fund (VMNFX) N-CSR 4 Mar 25 Certified annual shareholder report (management investment company) Financial data

Form N-CSR Cover

Form N-CSR Cover	12 Months Ended
	Dec. 31, 2024
Shareholder Report [Line Items]
Document Type	N-CSR
Amendment Flag	false
Registrant Name	Vanguard Montgomery Funds
Entity Central Index Key	0001409957
Entity Investment Company Type	N-1A
Document Period End Date	Dec. 31, 2024

Shareholder Report

Shareholder Report	12 Months Ended
	Dec. 31, 2024 USD ($) Holding
Shareholder Report [Line Items]
Document Type	N-CSR
Amendment Flag	false
Registrant Name	Vanguard Montgomery Funds
Entity Central Index Key	0001409957
Entity Investment Company Type	N-1A
Document Period End Date	Dec. 31, 2024
C000054090
Shareholder Report [Line Items]
Fund Name	Market Neutral Fund
Class Name	Investor Shares
Trading Symbol	VMNFX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Vanguard Market Neutral Fund (the "Fund") for the period of January 1, 2024, to December 31, 2024.
Shareholder Report Annual or Semi-Annual	Annual Shareholder Report
Additional Information [Text Block]	You can find additional information about the Fund at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature. You can also request this information by contacting us at 800-662-7447.
Additional Information Phone Number	800-662-7447
Additional Information Website	https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Investor Shares $144 1.40%
Expenses Paid, Amount	$ 144
Expense Ratio, Percent	1.40%
Factors Affecting Performance [Text Block]	How did the Fund perform during the reporting period? For the 12 months ended December 31, 2024, the Fund outperformed its benchmark. U.S. economic growth hovered around 3% on a year-over-year basis for much of the period, and consumer price inflation trended lower, falling below 3% in July. The Federal Reserve began cutting short-term interest rates in September, which boosted stock returns, as did the prospect of tax cuts and deregulation under the incoming administration. The Fund’s relative performance benefited from its positions in six of 11 economic sectors, most notably consumer staples, real estate, and financials. The largest performance drags owed to industrials, health care, and communication services. At the individual stock level, roughly 50% of the approximately 800 stocks the Fund held during the period helped its relative performance, while roughly 40% detracted and 10% had no impact. Even modest levels of short-term outperformance can compound into strong long-term results. The Fund outpaced its benchmark for the decade ended December 31, 2024.
Line Graph [Table Text Block]	Investor Shares Spliced Market Neutral Index in USD Dow Jones U.S. Total Stock Market Float Adjusted Index 2014 $50,000 $50,000 $50,000 2015 $50,087 $50,000 $50,901 2015 $49,435 $50,000 $50,961 2015 $52,913 $50,000 $47,257 2015 $52,704 $50,005 $50,220 2016 $54,009 $50,030 $50,680 2016 $51,400 $50,062 $52,005 2016 $50,965 $50,097 $54,311 2016 $54,083 $50,139 $56,558 2017 $52,775 $50,199 $59,834 2017 $51,684 $50,291 $61,634 2017 $51,509 $50,419 $64,449 2017 $51,437 $50,560 $68,527 2018 $52,220 $50,736 $68,113 2018 $51,734 $50,958 $70,751 2018 $53,059 $51,213 $75,779 2018 $51,743 $51,502 $64,897 2019 $49,028 $51,809 $74,009 2019 $46,265 $52,127 $77,035 2019 $47,602 $52,420 $77,911 2019 $46,793 $52,662 $84,951 2020 $44,493 $52,867 $67,144 2020 $44,447 $52,938 $81,976 2020 $43,435 $52,955 $89,415 2020 $41,377 $52,968 $102,613 2021 $44,292 $52,977 $109,230 2021 $45,218 $52,981 $118,283 2021 $46,699 $52,986 $118,142 2021 $50,992 $52,992 $128,940 2022 $53,263 $53,007 $121,978 2022 $54,746 $53,084 $101,441 2022 $55,674 $53,322 $96,812 2022 $57,864 $53,788 $103,760 2023 $57,121 $54,391 $111,276 2023 $58,382 $55,073 $120,615 2023 $63,053 $55,832 $116,647 2023 $64,947 $56,616 $130,798 2024 $68,559 $57,393 $143,938 2024 $68,264 $58,179 $148,600 2024 $70,720 $58,976 $157,754 2024 $68,743 $59,700 $162,026
Average Annual Return [Table Text Block]	1 Year 5 Years 10 Years Investor Shares 5.84% 8.00% 3.23% Spliced Market Neutral Index in USD 5.45% 2.54% 1.79% Dow Jones U.S. Total Stock Market Float Adjusted Index 23.88% 13.78% 12.48%
AssetsNet	$ 431,000,000
Holdings Count | Holding	461
Advisory Fees Paid, Amount	$ 124,000
InvestmentCompanyPortfolioTurnover	104%
Additional Fund Statistics [Text Block]	Fund Statistics (as of December 31, 2024 Fund Net Assets (in millions) $431 Number of Portfolio Holdings 461 Portfolio Turnover Rate 104% Total Investment Advisory Fees (in thousands) $124
Additional Fund Statistics Significance or Limits [Text Block]	Where can I find additional information about the Fund? Additional information about the Fund, including its prospectus, financial information, holdings, and proxy voting information is available at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature.
Holdings [Text Block]	This table reflects the Fund's investments, including short-term investments and other assets and liabilities. Portfolio Composition % of Net Assets (as of December 31, 2024 Long Portfolio Short Portfolio Communication Services 3.7% 4.2% Consumer Discretionary 10.0% 10.3% Consumer Staples 5.0% 4.8% Energy 4.5% 4.2% Financials 21.9% 21.7% Health Care 11.3% 10.8% Industrials 16.2% 17.0% Information Technology 12.2% 12.5% Materials 3.4% 3.3% Real Estate 5.6% 5.4% Utilities 3.6% 3.7% Other Assets and Liabilities—Net 2.6% 2.1%
Material Fund Change [Text Block]
Updated Prospectus Web Address	https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
C000054091
Shareholder Report [Line Items]
Fund Name	Market Neutral Fund
Class Name	Institutional Shares
Trading Symbol	VMNIX
Annual or Semi-Annual Statement [Text Block]	This annual shareholder report contains important information about Vanguard Market Neutral Fund (the "Fund") for the period of January 1, 2024, to December 31, 2024.
Shareholder Report Annual or Semi-Annual	Annual Shareholder Report
Additional Information [Text Block]	You can find additional information about the Fund at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature. You can also request this information by contacting us at 800-662-7447.
Additional Information Phone Number	800-662-7447
Additional Information Website	https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature
Expenses [Text Block]	What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Share Class Name Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Institutional Shares $138 1.34%
Expenses Paid, Amount	$ 138
Expense Ratio, Percent	1.34%
Factors Affecting Performance [Text Block]	How did the Fund perform during the reporting period? For the 12 months ended December 31, 2024, the Fund outperformed its benchmark. U.S. economic growth hovered around 3% on a year-over-year basis for much of the period, and consumer price inflation trended lower, falling below 3% in July. The Federal Reserve began cutting short-term interest rates in September, which boosted stock returns, as did the prospect of tax cuts and deregulation under the incoming administration. The Fund’s relative performance benefited from its positions in six of 11 economic sectors, most notably consumer staples, real estate, and financials. The largest performance drags owed to industrials, health care, and communication services. At the individual stock level, roughly 50% of the approximately 800 stocks the Fund held during the period helped its relative performance, while roughly 40% detracted and 10% had no impact. Even modest levels of short-term outperformance can compound into strong long-term results. The Fund outpaced its benchmark for the decade ended December 31, 2024.
Line Graph [Table Text Block]	Institutional Shares Spliced Market Neutral Index in USD Dow Jones U.S. Total Stock Market Float Adjusted Index 2014 $5,000,000 $5,000,000 $5,000,000 2015 $5,008,734 $5,000,000 $5,090,054 2015 $4,943,231 $5,000,000 $5,096,078 2015 $5,296,943 $5,000,000 $4,725,720 2015 $5,275,991 $5,000,500 $5,022,045 2016 $5,407,126 $5,003,001 $5,067,957 2016 $5,149,228 $5,006,246 $5,200,452 2016 $5,105,516 $5,009,749 $5,431,090 2016 $5,418,471 $5,013,855 $5,655,796 2017 $5,287,932 $5,019,927 $5,983,419 2017 $5,178,133 $5,029,075 $6,163,391 2017 $5,164,957 $5,041,913 $6,444,880 2017 $5,156,777 $5,056,027 $6,852,694 2018 $5,236,638 $5,073,645 $6,811,260 2018 $5,187,739 $5,095,770 $7,075,085 2018 $5,321,100 $5,121,250 $7,577,897 2018 $5,190,321 $5,150,207 $6,489,745 2019 $4,917,750 $5,180,945 $7,400,938 2019 $4,639,303 $5,212,722 $7,703,509 2019 $4,778,526 $5,242,042 $7,791,070 2019 $4,698,504 $5,266,226 $8,495,073 2020 $4,467,663 $5,286,650 $6,714,437 2020 $4,463,024 $5,293,789 $8,197,568 2020 $4,365,598 $5,295,492 $8,941,465 2020 $4,154,494 $5,296,790 $10,261,256 2021 $4,448,576 $5,297,745 $10,922,971 2021 $4,541,936 $5,298,130 $11,828,254 2021 $4,691,311 $5,298,609 $11,814,249 2021 $5,126,357 $5,299,227 $12,894,041 2022 $5,350,869 $5,300,712 $12,197,836 2022 $5,505,221 $5,308,354 $10,144,127 2022 $5,594,090 $5,332,186 $9,681,223 2022 $5,816,908 $5,378,806 $10,375,952 2023 $5,742,901 $5,439,149 $11,127,602 2023 $5,874,922 $5,507,260 $12,061,484 2023 $6,346,425 $5,583,167 $11,664,700 2023 $6,534,361 $5,661,628 $13,079,813 2024 $6,895,246 $5,739,254 $14,393,774 2024 $6,870,443 $5,817,880 $14,860,033 2024 $7,123,434 $5,897,631 $15,775,361 2024 $6,920,824 $5,970,013 $16,202,621
Average Annual Return [Table Text Block]	1 Year 5 Years 10 Years Institutional Shares 5.91% 8.05% 3.30% Spliced Market Neutral Index in USD 5.45% 2.54% 1.79% Dow Jones U.S. Total Stock Market Float Adjusted Index 23.88% 13.78% 12.48%
AssetsNet	$ 431,000,000
Holdings Count | Holding	461
Advisory Fees Paid, Amount	$ 124,000
InvestmentCompanyPortfolioTurnover	104%
Additional Fund Statistics [Text Block]	Fund Statistics (as of December 31, 2024 Fund Net Assets (in millions) $431 Number of Portfolio Holdings 461 Portfolio Turnover Rate 104% Total Investment Advisory Fees (in thousands) $124
Additional Fund Statistics Significance or Limits [Text Block]	Where can I find additional information about the Fund? Additional information about the Fund, including its prospectus, financial information, holdings, and proxy voting information is available at https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature.
Holdings [Text Block]	This table reflects the Fund's investments, including short-term investments and other assets and liabilities. Portfolio Composition % of Net Assets (as of December 31, 2024 Long Portfolio Short Portfolio Communication Services 3.7% 4.2% Consumer Discretionary 10.0% 10.3% Consumer Staples 5.0% 4.8% Energy 4.5% 4.2% Financials 21.9% 21.7% Health Care 11.3% 10.8% Industrials 16.2% 17.0% Information Technology 12.2% 12.5% Materials 3.4% 3.3% Real Estate 5.6% 5.4% Utilities 3.6% 3.7% Other Assets and Liabilities—Net 2.6% 2.1%
Material Fund Change [Text Block]
Updated Prospectus Web Address	https://personal1.vanguard.com/ngf-next-gen-form-webapp/fund-literature

Shareholder Report, Line Graph

Shareholder Report, Line Graph (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
C000054090
Account Value [Line Items]
Account Value	$ 68,743	$ 70,720	$ 68,264	$ 68,559	$ 64,947	$ 63,053	$ 58,382	$ 57,121	$ 57,864	$ 55,674	$ 54,746	$ 53,263	$ 50,992	$ 46,699	$ 45,218	$ 44,292	$ 41,377	$ 43,435	$ 44,447	$ 44,493	$ 46,793	$ 47,602	$ 46,265	$ 49,028	$ 51,743	$ 53,059	$ 51,734	$ 52,220	$ 51,437	$ 51,509	$ 51,684	$ 52,775	$ 54,083	$ 50,965	$ 51,400	$ 54,009	$ 52,704	$ 52,913	$ 49,435	$ 50,087	$ 50,000
C000054091
Account Value [Line Items]
Line Graph and Table Measure Name	Institutional Shares
Account Value	$ 6,920,824	7,123,434	6,870,443	6,895,246	6,534,361	6,346,425	5,874,922	5,742,901	5,816,908	5,594,090	5,505,221	5,350,869	5,126,357	4,691,311	4,541,936	4,448,576	4,154,494	4,365,598	4,463,024	4,467,663	4,698,504	4,778,526	4,639,303	4,917,750	5,190,321	5,321,100	5,187,739	5,236,638	5,156,777	5,164,957	5,178,133	5,287,932	5,418,471	5,105,516	5,149,228	5,407,126	5,275,991	5,296,943	4,943,231	5,008,734	5,000,000
NACC2 Index: Dow Jones U.S. Total Stock Market Float Adjusted Index
Account Value [Line Items]
Account Value	$ 162,026	157,754	148,600	143,938	130,798	116,647	120,615	111,276	103,760	96,812	101,441	121,978	128,940	118,142	118,283	109,230	102,613	89,415	81,976	67,144	84,951	77,911	77,035	74,009	64,897	75,779	70,751	68,113	68,527	64,449	61,634	59,834	56,558	54,311	52,005	50,680	50,220	47,257	50,961	50,901	50,000
NACC2 Index: Dow Jones U.S. Total Stock Market Float Adjusted Index
Account Value [Line Items]
Line Graph and Table Measure Name	Dow Jones U.S. Total Stock Market Float Adjusted Index
Account Value	$ 16,202,621	15,775,361	14,860,033	14,393,774	13,079,813	11,664,700	12,061,484	11,127,602	10,375,952	9,681,223	10,144,127	12,197,836	12,894,041	11,814,249	11,828,254	10,922,971	10,261,256	8,941,465	8,197,568	6,714,437	8,495,073	7,791,070	7,703,509	7,400,938	6,489,745	7,577,897	7,075,085	6,811,260	6,852,694	6,444,880	6,163,391	5,983,419	5,655,796	5,431,090	5,200,452	5,067,957	5,022,045	4,725,720	5,096,078	5,090,054	5,000,000
NACC2 Index: Spliced Market Neutral Index in USD
Account Value [Line Items]
Account Value	$ 59,700	58,976	58,179	57,393	56,616	55,832	55,073	54,391	53,788	53,322	53,084	53,007	52,992	52,986	52,981	52,977	52,968	52,955	52,938	52,867	52,662	52,420	52,127	51,809	51,502	51,213	50,958	50,736	50,560	50,419	50,291	50,199	50,139	50,097	50,062	50,030	50,005	50,000	50,000	50,000	50,000
NACC2 Index: Spliced Market Neutral Index in USD
Account Value [Line Items]
Line Graph and Table Measure Name	Spliced Market Neutral Index in USD
Account Value	$ 5,970,013	$ 5,897,631	$ 5,817,880	$ 5,739,254	$ 5,661,628	$ 5,583,167	$ 5,507,260	$ 5,439,149	$ 5,378,806	$ 5,332,186	$ 5,308,354	$ 5,300,712	$ 5,299,227	$ 5,298,609	$ 5,298,130	$ 5,297,745	$ 5,296,790	$ 5,295,492	$ 5,293,789	$ 5,286,650	$ 5,266,226	$ 5,242,042	$ 5,212,722	$ 5,180,945	$ 5,150,207	$ 5,121,250	$ 5,095,770	$ 5,073,645	$ 5,056,027	$ 5,041,913	$ 5,029,075	$ 5,019,927	$ 5,013,855	$ 5,009,749	$ 5,006,246	$ 5,003,001	$ 5,000,500	$ 5,000,000	$ 5,000,000	$ 5,000,000	$ 5,000,000

Shareholder Report, Average Ann

Shareholder Report, Average Annual Return (Details)	12 Months Ended	60 Months Ended	120 Months Ended
	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2024
C000054091
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Institutional Shares
Without Sales Load [Member] | C000054090
Average Annual Return [Line Items]
Average Annual Return, Percent	5.84%	8%	3.23%
Without Sales Load [Member] | C000054091
Average Annual Return [Line Items]
Average Annual Return, Percent	5.91%	8.05%	3.30%
NACC2 Index: Dow Jones U.S. Total Stock Market Float Adjusted Index
Average Annual Return [Line Items]
Average Annual Return, Percent	23.88%	13.78%	12.48%
NACC2 Index: Dow Jones U.S. Total Stock Market Float Adjusted Index
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Dow Jones U.S. Total Stock Market Float Adjusted Index
Average Annual Return, Percent	23.88%	13.78%	12.48%
NACC2 Index: Spliced Market Neutral Index in USD
Average Annual Return [Line Items]
Average Annual Return, Percent	5.45%	2.54%	1.79%
NACC2 Index: Spliced Market Neutral Index in USD
Average Annual Return [Line Items]
Line Graph and Table Measure Name	Spliced Market Neutral Index in USD
Average Annual Return, Percent	5.45%	2.54%	1.79%

Shareholder Report, Holdings (D

Shareholder Report, Holdings (Details)	Dec. 31, 2024
C000054090 | Communication Services
Holdings [Line Items]
Percent of Net Long Exposure	3.70%
Percent of Net Short Exposure	4.20%
C000054090 | Consumer Discretionary
Holdings [Line Items]
Percent of Net Long Exposure	10%
Percent of Net Short Exposure	10.30%
C000054090 | Consumer Staples
Holdings [Line Items]
Percent of Net Long Exposure	5%
Percent of Net Short Exposure	4.80%
C000054090 | Energy
Holdings [Line Items]
Percent of Net Long Exposure	4.50%
Percent of Net Short Exposure	4.20%
C000054090 | Financials
Holdings [Line Items]
Percent of Net Long Exposure	21.90%
Percent of Net Short Exposure	21.70%
C000054090 | Health Care
Holdings [Line Items]
Percent of Net Long Exposure	11.30%
Percent of Net Short Exposure	10.80%
C000054090 | Industrials
Holdings [Line Items]
Percent of Net Long Exposure	16.20%
Percent of Net Short Exposure	17%
C000054090 | Information Technology
Holdings [Line Items]
Percent of Net Long Exposure	12.20%
Percent of Net Short Exposure	12.50%
C000054090 | Materials
Holdings [Line Items]
Percent of Net Long Exposure	3.40%
Percent of Net Short Exposure	3.30%
C000054090 | Real Estate
Holdings [Line Items]
Percent of Net Long Exposure	5.60%
Percent of Net Short Exposure	5.40%
C000054090 | Utilities
Holdings [Line Items]
Percent of Net Long Exposure	3.60%
Percent of Net Short Exposure	3.70%
C000054090 | Sector Other Net Line
Holdings [Line Items]
Percent of Net Long Exposure	2.60%
Percent of Net Short Exposure	2.10%
C000054091 | Communication Services
Holdings [Line Items]
Percent of Net Long Exposure	3.70%
Percent of Net Short Exposure	4.20%
C000054091 | Consumer Discretionary
Holdings [Line Items]
Percent of Net Long Exposure	10%
Percent of Net Short Exposure	10.30%
C000054091 | Consumer Staples
Holdings [Line Items]
Percent of Net Long Exposure	5%
Percent of Net Short Exposure	4.80%
C000054091 | Energy
Holdings [Line Items]
Percent of Net Long Exposure	4.50%
Percent of Net Short Exposure	4.20%
C000054091 | Financials
Holdings [Line Items]
Percent of Net Long Exposure	21.90%
Percent of Net Short Exposure	21.70%
C000054091 | Health Care
Holdings [Line Items]
Percent of Net Long Exposure	11.30%
Percent of Net Short Exposure	10.80%
C000054091 | Industrials
Holdings [Line Items]
Percent of Net Long Exposure	16.20%
Percent of Net Short Exposure	17%
C000054091 | Information Technology
Holdings [Line Items]
Percent of Net Long Exposure	12.20%
Percent of Net Short Exposure	12.50%
C000054091 | Materials
Holdings [Line Items]
Percent of Net Long Exposure	3.40%
Percent of Net Short Exposure	3.30%
C000054091 | Real Estate
Holdings [Line Items]
Percent of Net Long Exposure	5.60%
Percent of Net Short Exposure	5.40%
C000054091 | Utilities
Holdings [Line Items]
Percent of Net Long Exposure	3.60%
Percent of Net Short Exposure	3.70%
C000054091 | Sector Other Net Line
Holdings [Line Items]
Percent of Net Long Exposure	2.60%
Percent of Net Short Exposure	2.10%