v3.26.1
Shareholder Report
 6 Months Ended
Feb. 28, 2026
USD ($)
$ / shares
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name Putnam Investment Funds
Entity Central Index Key 0000932101
Entity Investment Company Type N-1A
Document Period End Date Feb. 28, 2026
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Class A  
Shareholder Report [Line Items]  
Fund Name Putnam International Small Cap Fund
Class Name Class A
Trading Symbol PNVAX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam International Small Cap Fund (previously known as Putnam International Capital Opportunities Fund) for the period  September 1, 2025, to February 28, 2026.
Additional Information [Text Block] You can find additional information about the Fund at https://www.franklintempleton.com/regulatory-fund-documents. You can also request this information by contacting us at (800) 225-1581.
Additional Information Phone Number (800) 225-1581
Additional Information Website https://www.franklintempleton.com/regulatory-fund-documents
Expenses [Text Block]
WHAT WERE THE FUND COSTS FOR THE LAST SIX MONTHS? (based on a hypothetical $10,000 investment)
Class Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment†
Class A
$74
1.42%
[1]
Expenses Paid, Amount $ 74
Expense Ratio, Percent 1.42%
Net Assets $ 364,971,662
Holdings Count | $ / shares 65
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of February 28, 2026)
Total Net Assets
$364,971,662
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
65
Portfolio Turnover Rate
19%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of February 28, 2026)
Portfolio Composition* (% of Total Investments)
image
 [2]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
Class C  
Shareholder Report [Line Items]  
Fund Name Putnam International Small Cap Fund
Class Name Class C
Trading Symbol PUVCX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam International Small Cap Fund (previously known as Putnam International Capital Opportunities Fund) for the period  September 1, 2025, to February 28, 2026.
Additional Information [Text Block] You can find additional information about the Fund at https://www.franklintempleton.com/regulatory-fund-documents. You can also request this information by contacting us at (800) 225-1581.
Additional Information Phone Number (800) 225-1581
Additional Information Website https://www.franklintempleton.com/regulatory-fund-documents
Expenses [Text Block]
WHAT WERE THE FUND COSTS FOR THE LAST SIX MONTHS? (based on a hypothetical $10,000 investment)
Class Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment†
Class C
$113
2.17%
[3]
Expenses Paid, Amount $ 113
Expense Ratio, Percent 2.17%
Net Assets $ 364,971,662
Holdings Count | $ / shares 65
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of February 28, 2026)
Total Net Assets
$364,971,662
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
65
Portfolio Turnover Rate
19%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of February 28, 2026)
Portfolio Composition* (% of Total Investments)
image
 [4]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
Class R  
Shareholder Report [Line Items]  
Fund Name Putnam International Small Cap Fund
Class Name Class R
Trading Symbol PICRX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam International Small Cap Fund (previously known as Putnam International Capital Opportunities Fund) for the period  September 1, 2025, to February 28, 2026.
Additional Information [Text Block] You can find additional information about the Fund at https://www.franklintempleton.com/regulatory-fund-documents. You can also request this information by contacting us at (800) 225-1581.
Additional Information Phone Number (800) 225-1581
Additional Information Website https://www.franklintempleton.com/regulatory-fund-documents
Expenses [Text Block]
WHAT WERE THE FUND COSTS FOR THE LAST SIX MONTHS? (based on a hypothetical $10,000 investment)
Class Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment†
Class R
$87
1.67%
[5]
Expenses Paid, Amount $ 87
Expense Ratio, Percent 1.67%
Net Assets $ 364,971,662
Holdings Count | $ / shares 65
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of February 28, 2026)
Total Net Assets
$364,971,662
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
65
Portfolio Turnover Rate
19%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of February 28, 2026)
Portfolio Composition* (% of Total Investments)
image
 [6]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
Class R6  
Shareholder Report [Line Items]  
Fund Name Putnam International Small Cap Fund
Class Name Class R6
Trading Symbol PICOX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam International Small Cap Fund (previously known as Putnam International Capital Opportunities Fund) for the period  September 1, 2025, to February 28, 2026.
Additional Information [Text Block] You can find additional information about the Fund at https://www.franklintempleton.com/regulatory-fund-documents. You can also request this information by contacting us at (800) 225-1581.
Additional Information Phone Number (800) 225-1581
Additional Information Website https://www.franklintempleton.com/regulatory-fund-documents
Expenses [Text Block]
WHAT WERE THE FUND COSTS FOR THE LAST SIX MONTHS? (based on a hypothetical $10,000 investment)
Class Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment*,†
Class R6
$53
1.01%
[7],[8]
Expenses Paid, Amount $ 53
Expense Ratio, Percent 1.01%
Net Assets $ 364,971,662
Holdings Count | $ / shares 65
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of February 28, 2026)
Total Net Assets
$364,971,662
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
65
Portfolio Turnover Rate
19%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of February 28, 2026)
Portfolio Composition* (% of Total Investments)
image
 [9]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
Class Y  
Shareholder Report [Line Items]  
Fund Name Putnam International Small Cap Fund
Class Name Class Y
Trading Symbol PIVYX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam International Small Cap Fund (previously known as Putnam International Capital Opportunities Fund) for the period  September 1, 2025, to February 28, 2026.
Additional Information [Text Block] You can find additional information about the Fund at https://www.franklintempleton.com/regulatory-fund-documents. You can also request this information by contacting us at (800) 225-1581.
Additional Information Phone Number (800) 225-1581
Additional Information Website https://www.franklintempleton.com/regulatory-fund-documents
Expenses [Text Block]
WHAT WERE THE FUND COSTS FOR THE LAST SIX MONTHS? (based on a hypothetical $10,000 investment)
Class Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment*,†
Class Y
$53
1.01%
[10],[11]
Expenses Paid, Amount $ 53
Expense Ratio, Percent 1.01%
Net Assets $ 364,971,662
Holdings Count | $ / shares 65
Investment Company Portfolio Turnover 19.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of February 28, 2026)
Total Net Assets
$364,971,662
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
65
Portfolio Turnover Rate
19%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of February 28, 2026)
Portfolio Composition* (% of Total Investments)
image
 [12]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
[1]
† Annualized.
[2]
* Does not include derivatives, except purchased options, if any.  
[3]
† Annualized.
[4]
* Does not include derivatives, except purchased options, if any.  
[5]
† Annualized.
[6]
* Does not include derivatives, except purchased options, if any.  
[7]
* Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[8]
† Annualized.
[9]
* Does not include derivatives, except purchased options, if any.  
[10]
* Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[11]
† Annualized.
[12]
* Does not include derivatives, except purchased options, if any.