v3.26.1
Shareholder Report
 6 Months Ended
Mar. 31, 2026
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name AMG Funds I
Entity Central Index Key 0000882443
Entity Investment Company Type N-1A
Document Period End Date Mar. 31, 2026
C000130199 [Member]  
Shareholder Report [Line Items]  
Fund Name AMG Boston Common Global Impact Fund
Class Name Class I
Trading Symbol BRWIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about AMG Boston Common Global Impact Fund (the “Fund”) for the period of October 1, 2025 to March 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://wealth.amg.com/literature. You can also request this information by contacting us at 800.548.4539.
Additional Information Phone Number 800.548.4539
Additional Information Website https://wealth.amg.com/literature
Expenses [Text Block]
Fund Expenses
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Fund (Class) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
AMG Boston Common Global Impact Fund
(Class I/BRWIX)		 $48 0.93%
Expenses Paid, Amount $ 48
Expense Ratio, Percent 0.93%
Net Assets $ 548,619,300
Holdings Count | Holding 64
Advisory Fees Paid, Amount $ 2,023,100
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics (as of March 31, 2026)
Fund net assets $548,619,300
Total number of portfolio holdings 64
Net advisory fees paid $2,023,100
Portfolio turnover rate as of the end of the reporting period 16%
Holdings [Text Block]
Graphical Representation of Holdings (as of March 31, 2026)
Top ten holdings and portfolio breakdown are shown as a percentage of net assets of the Fund and country allocation is shown as a percentage of total long-term investments of the Fund.
Top Ten Holdings
NVIDIA Corp. (United States) 4.9%
Alphabet, Inc., Class A (United States) 4.6%
Taiwan Semiconductor Manufacturing Co., Ltd., Sponsored ADR (Taiwan) 4.4%
Samsung Electronics Co., Ltd. (South Korea) 3.4%
Microsoft Corp. (United States) 3.2%
Apple, Inc. (United States) 3.0%
Netflix, Inc. (United States) 2.3%
Broadcom, Inc. (United States) 2.0%
Roche Holding AG (Switzerland) 2.0%
Merck & Co., Inc. (United States) 1.9%
Top Ten as a Group 31.7%
Portfolio Breakdown
Graphical Representation - Allocation 1 Chart
Country Allocation
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
Top Ten Holdings
NVIDIA Corp. (United States) 4.9%
Alphabet, Inc., Class A (United States) 4.6%
Taiwan Semiconductor Manufacturing Co., Ltd., Sponsored ADR (Taiwan) 4.4%
Samsung Electronics Co., Ltd. (South Korea) 3.4%
Microsoft Corp. (United States) 3.2%
Apple, Inc. (United States) 3.0%
Netflix, Inc. (United States) 2.3%
Broadcom, Inc. (United States) 2.0%
Roche Holding AG (Switzerland) 2.0%
Merck & Co., Inc. (United States) 1.9%
Top Ten as a Group 31.7%
C000130200 [Member]  
Shareholder Report [Line Items]  
Fund Name AMG Veritas Global Real Return Fund
Class Name Class I
Trading Symbol BLUEX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about AMG Veritas Global Real Return Fund (the “Fund”) for the period of October 1, 2025 to March 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://wealth.amg.com/literature. You can also request this information by contacting us at 800.548.4539.
Additional Information Phone Number 800.548.4539
Additional Information Website https://wealth.amg.com/literature
Expenses [Text Block]
Fund Expenses
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Fund (Class) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
AMG Veritas Global Real Return Fund
(Class I/BLUEX)		 $55 1.16%
Expenses Paid, Amount $ 55
Expense Ratio, Percent 1.16%
Net Assets $ 86,688,301
Holdings Count | Holding 34
Advisory Fees Paid, Amount $ 375,369
Investment Company Portfolio Turnover 16.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics (as of March 31, 2026)
Fund net assets $86,688,301
Total number of portfolio holdings 34
Net advisory fees paid $375,369
Portfolio turnover rate as of the end of the reporting period 16%
Holdings [Text Block]
Graphical Representation of Holdings (as of March 31, 2026)
Top ten holdings and portfolio breakdown are shown as a percentage of net assets of the Fund and country allocation is shown as a percentage of total long-term investments of the Fund.
Top Ten Holdings
Vinci, S.A. (France) 5.5%
Amazon.com, Inc. (United States) 5.0%
London Stock Exchange Group PLC (United Kingdom) 4.9%
Canadian Pacific Kansas City, Ltd. (Canada) 4.9%
Safran, S.A. (France) 4.8%
Microsoft Corp. (United States) 4.3%
Aon PLC, Class A (United Kingdom) 4.3%
Mastercard, Inc., Class A (United States) 4.2%
Airbus SE (France) 4.2%
UnitedHealth Group, Inc. (United States) 4.1%
Top Ten as a Group 46.2%
Portfolio Breakdown
Graphical Representation - Allocation 1 Chart
Country Allocation
Graphical Representation - Allocation 2 Chart
Largest Holdings [Text Block]
Top Ten Holdings
Vinci, S.A. (France) 5.5%
Amazon.com, Inc. (United States) 5.0%
London Stock Exchange Group PLC (United Kingdom) 4.9%
Canadian Pacific Kansas City, Ltd. (Canada) 4.9%
Safran, S.A. (France) 4.8%
Microsoft Corp. (United States) 4.3%
Aon PLC, Class A (United Kingdom) 4.3%
Mastercard, Inc., Class A (United States) 4.2%
Airbus SE (France) 4.2%
UnitedHealth Group, Inc. (United States) 4.1%
Top Ten as a Group 46.2%
C000248365 [Member]  
Shareholder Report [Line Items]  
Fund Name AMG Systematica Managed Futures Strategy Fund
Class Name Class Z
Trading Symbol SMFZX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about AMG Systematica Managed Futures Strategy Fund (the “Fund”) for the period of October 1, 2025 to March 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://wealth.amg.com/literature. You can also request this information by contacting us at 800.548.4539.
Additional Information Phone Number 800.548.4539
Additional Information Website https://wealth.amg.com/literature
Expenses [Text Block]
Fund Expenses
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Fund (Class) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
AMG Systematica Managed Futures Strategy Fund
(Class Z/SMFZX)		 $57 1.10%
Expenses Paid, Amount $ 57
Expense Ratio, Percent 1.10%
Net Assets $ 6,245,580
Holdings Count | Holding 600
Advisory Fees Paid, Amount $ 0
Investment Company Portfolio Turnover 0.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics (as of March 31, 2026)
Fund net assets $6,245,580
Total number of portfolio holdings 600
Net advisory fees paid $0
Portfolio turnover rate as of the end of the reporting period 0%
Holdings [Text Block]
Graphical Representation of Holdings (as of March 31, 2026)
The portfolio breakdown is shown as a percentage of net assets of the Fund and notional allocation is shown as a percentage of total notional value of the Fund's derivatives holdings. The portfolio breakdown and notional allocation are inclusive of the Fund's wholly-owned subsidiary.
Portfolio Breakdown
Graphical Representation - Allocation 1 Chart
NOTIONAL ALLOCATION
Interest Rate Futures Contracts 114.6%
Forward Foreign Currency Exchange Contracts 19.9%
Commodity Futures Contracts (15.0)%
Equity Futures Contracts (19.5)%
C000248367 [Member]  
Shareholder Report [Line Items]  
Fund Name AMG Systematica Managed Futures Strategy Fund
Class Name Class I
Trading Symbol SMFIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about AMG Systematica Managed Futures Strategy Fund (the “Fund”) for the period of October 1, 2025 to March 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://wealth.amg.com/literature. You can also request this information by contacting us at 800.548.4539.
Additional Information Phone Number 800.548.4539
Additional Information Website https://wealth.amg.com/literature
Expenses [Text Block]
Fund Expenses
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Fund (Class) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
AMG Systematica Managed Futures Strategy Fund
(Class I/SMFIX)		 $57 1.10%
Expenses Paid, Amount $ 57
Expense Ratio, Percent 1.10%
Net Assets $ 6,245,580
Holdings Count | Holding 600
Advisory Fees Paid, Amount $ 0
Investment Company Portfolio Turnover 0.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics (as of March 31, 2026)
Fund net assets $6,245,580
Total number of portfolio holdings 600
Net advisory fees paid $0
Portfolio turnover rate as of the end of the reporting period 0%
Holdings [Text Block]
Graphical Representation of Holdings (as of March 31, 2026)
The portfolio breakdown is shown as a percentage of net assets of the Fund and notional allocation is shown as a percentage of total notional value of the Fund's derivatives holdings. The portfolio breakdown and notional allocation are inclusive of the Fund's wholly-owned subsidiary.
Portfolio Breakdown
Graphical Representation - Allocation 1 Chart
NOTIONAL ALLOCATION
Interest Rate Futures Contracts 114.6%
Forward Foreign Currency Exchange Contracts 19.9%
Commodity Futures Contracts (15.0)%
Equity Futures Contracts (19.5)%
C000248366 [Member]  
Shareholder Report [Line Items]  
Fund Name AMG Systematica Managed Futures Strategy Fund
Class Name Class N
Trading Symbol SMFNX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about AMG Systematica Managed Futures Strategy Fund (the “Fund”) for the period of October 1, 2025 to March 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://wealth.amg.com/literature. You can also request this information by contacting us at 800.548.4539.
Additional Information Phone Number 800.548.4539
Additional Information Website https://wealth.amg.com/literature
Expenses [Text Block]
Fund Expenses
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Fund (Class) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
AMG Systematica Managed Futures Strategy Fund
(Class N/SMFNX)		 $57 1.10%
Expenses Paid, Amount $ 57
Expense Ratio, Percent 1.10%
Net Assets $ 6,245,580
Holdings Count | Holding 600
Advisory Fees Paid, Amount $ 0
Investment Company Portfolio Turnover 0.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics (as of March 31, 2026)
Fund net assets $6,245,580
Total number of portfolio holdings 600
Net advisory fees paid $0
Portfolio turnover rate as of the end of the reporting period 0%
Holdings [Text Block]
Graphical Representation of Holdings (as of March 31, 2026)
The portfolio breakdown is shown as a percentage of net assets of the Fund and notional allocation is shown as a percentage of total notional value of the Fund's derivatives holdings. The portfolio breakdown and notional allocation are inclusive of the Fund's wholly-owned subsidiary.
Portfolio Breakdown
Graphical Representation - Allocation 1 Chart
NOTIONAL ALLOCATION
Interest Rate Futures Contracts 114.6%
Forward Foreign Currency Exchange Contracts 19.9%
Commodity Futures Contracts (15.0)%
Equity Futures Contracts (19.5)%
C000257775 [Member]  
Shareholder Report [Line Items]  
Fund Name AMG Systematica Trend-Enhanced Markets Fund
Class Name Class N
Trading Symbol STMBX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about AMG Systematica Trend-Enhanced Markets Fund (the “Fund”) for the period of October 1, 2025 to March 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://wealth.amg.com/literature. You can also request this information by contacting us at 800.548.4539.
Additional Information Phone Number 800.548.4539
Additional Information Website https://wealth.amg.com/literature
Expenses [Text Block]
Fund Expenses
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Fund (Class) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
AMG Systematica Trend-Enhanced Markets Fund
(Class N/STMBX)		 $56 1.10%
Expenses Paid, Amount $ 56
Expense Ratio, Percent 1.10%
Net Assets $ 7,039,087
Holdings Count | Holding 589
Advisory Fees Paid, Amount $ 0
Investment Company Portfolio Turnover 0.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics (as of March 31, 2026)
Fund net assets $7,039,087
Total number of portfolio holdings 589
Net advisory fees paid $0
Portfolio turnover rate as of the end of the reporting period 0%
Holdings [Text Block]
Graphical Representation of Holdings (as of March 31, 2026)
The portfolio breakdown is shown as a percentage of net assets of the Fund and notional allocation is shown as a percentage of total notional value of the Fund's derivatives holdings. The portfolio breakdown and notional allocation are inclusive of the Fund's wholly-owned subsidiary.
Portfolio Breakdown
Graphical Representation - Allocation 1 Chart
NOTIONAL ALLOCATION
Interest Rate Futures Contracts 385.0%
Forward Foreign Currency Exchange Contracts 54.6%
Forward Commodity Exchange Contracts 0.0%
Commodity Futures Contracts (54.9)%
Equity Futures Contracts (284.7)%
C000257776 [Member]  
Shareholder Report [Line Items]  
Fund Name AMG Systematica Trend-Enhanced Markets Fund
Class Name Class I
Trading Symbol STMIX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about AMG Systematica Trend-Enhanced Markets Fund (the “Fund”) for the period of October 1, 2025 to March 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://wealth.amg.com/literature. You can also request this information by contacting us at 800.548.4539.
Additional Information Phone Number 800.548.4539
Additional Information Website https://wealth.amg.com/literature
Expenses [Text Block]
Fund Expenses
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Fund (Class) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
AMG Systematica Trend-Enhanced Markets Fund
(Class I/STMIX)		 $56 1.10%
Expenses Paid, Amount $ 56
Expense Ratio, Percent 1.10%
Net Assets $ 7,039,087
Holdings Count | Holding 589
Advisory Fees Paid, Amount $ 0
Investment Company Portfolio Turnover 0.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics (as of March 31, 2026)
Fund net assets $7,039,087
Total number of portfolio holdings 589
Net advisory fees paid $0
Portfolio turnover rate as of the end of the reporting period 0%
Holdings [Text Block]
Graphical Representation of Holdings (as of March 31, 2026)
The portfolio breakdown is shown as a percentage of net assets of the Fund and notional allocation is shown as a percentage of total notional value of the Fund's derivatives holdings. The portfolio breakdown and notional allocation are inclusive of the Fund's wholly-owned subsidiary.
Portfolio Breakdown
Graphical Representation - Allocation 1 Chart
NOTIONAL ALLOCATION
Interest Rate Futures Contracts 385.0%
Forward Foreign Currency Exchange Contracts 54.6%
Forward Commodity Exchange Contracts 0.0%
Commodity Futures Contracts (54.9)%
Equity Futures Contracts (284.7)%
C000257774 [Member]  
Shareholder Report [Line Items]  
Fund Name AMG Systematica Trend-Enhanced Markets Fund
Class Name Class Z
Trading Symbol STMZX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about AMG Systematica Trend-Enhanced Markets Fund (the “Fund”) for the period of October 1, 2025 to March 31, 2026.
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Additional Information [Text Block] You can find additional information about the Fund at https://wealth.amg.com/literature. You can also request this information by contacting us at 800.548.4539.
Additional Information Phone Number 800.548.4539
Additional Information Website https://wealth.amg.com/literature
Expenses [Text Block]
Fund Expenses
What were the Fund costs for the last six months?
(Based on a hypothetical $10,000 investment)
Fund (Class) Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment
AMG Systematica Trend-Enhanced Markets Fund
(Class Z/STMZX)		 $56 1.10%
Expenses Paid, Amount $ 56
Expense Ratio, Percent 1.10%
Net Assets $ 7,039,087
Holdings Count | Holding 589
Advisory Fees Paid, Amount $ 0
Investment Company Portfolio Turnover 0.00%
Additional Fund Statistics [Text Block]
Key Fund Statistics (as of March 31, 2026)
Fund net assets $7,039,087
Total number of portfolio holdings 589
Net advisory fees paid $0
Portfolio turnover rate as of the end of the reporting period 0%
Holdings [Text Block]
Graphical Representation of Holdings (as of March 31, 2026)
The portfolio breakdown is shown as a percentage of net assets of the Fund and notional allocation is shown as a percentage of total notional value of the Fund's derivatives holdings. The portfolio breakdown and notional allocation are inclusive of the Fund's wholly-owned subsidiary.
Portfolio Breakdown
Graphical Representation - Allocation 1 Chart
NOTIONAL ALLOCATION
Interest Rate Futures Contracts 385.0%
Forward Foreign Currency Exchange Contracts 54.6%
Forward Commodity Exchange Contracts 0.0%
Commodity Futures Contracts (54.9)%
Equity Futures Contracts (284.7)%