v3.26.1
Shareholder Report
 6 Months Ended
Apr. 30, 2026
USD ($)
$ / shares
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name Putnam Income Fund
Entity Central Index Key 0000081264
Entity Investment Company Type N-1A
Document Period End Date Apr. 30, 2026
Shareholder Report Annual or Semi-Annual semi-annual shareholder report
Class A  
Shareholder Report [Line Items]  
Fund Name Putnam Income Fund
Class Name Class A
Trading Symbol PINCX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam Income Fund for the period November 1, 2025, to April 30, 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
$35
0.71%
[1],[2]
Expenses Paid, Amount $ 35
Expense Ratio, Percent 0.71%
Net Assets $ 992,847,243
Holdings Count | $ / shares 1,189
Investment Company Portfolio Turnover 170.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of April 30, 2026)
Total Net Assets
$992,847,243
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
1,189
Portfolio Turnover Rate
170%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of April 30, 2026)
Portfolio Composition*  (% of Total Investments)
image
 [3]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
Class C  
Shareholder Report [Line Items]  
Fund Name Putnam Income Fund
Class Name Class C
Trading Symbol PUICX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam Income Fund for the period November 1, 2025, to April 30, 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
$73
1.46%
[4],[5]
Expenses Paid, Amount $ 73
Expense Ratio, Percent 1.46%
Net Assets $ 992,847,243
Holdings Count | $ / shares 1,189
Investment Company Portfolio Turnover 170.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of April 30, 2026)
Total Net Assets
$992,847,243
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
1,189
Portfolio Turnover Rate
170%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of April 30, 2026)
Portfolio Composition*  (% of Total Investments)
image
 [6]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
Class M  
Shareholder Report [Line Items]  
Fund Name Putnam Income Fund
Class Name Class M
Trading Symbol PNCMX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam Income Fund for the period November 1, 2025, to April 30, 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 M
$48
0.96%
[7],[8]
Expenses Paid, Amount $ 48
Expense Ratio, Percent 0.96%
Net Assets $ 992,847,243
Holdings Count | $ / shares 1,189
Investment Company Portfolio Turnover 170.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of April 30, 2026)
Total Net Assets
$992,847,243
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
1,189
Portfolio Turnover Rate
170%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of April 30, 2026)
Portfolio Composition*  (% of Total Investments)
image
 [9]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
Class R  
Shareholder Report [Line Items]  
Fund Name Putnam Income Fund
Class Name Class R
Trading Symbol PIFRX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam Income Fund for the period November 1, 2025, to April 30, 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
$48
0.96%
[10],[11]
Expenses Paid, Amount $ 48
Expense Ratio, Percent 0.96%
Net Assets $ 992,847,243
Holdings Count | $ / shares 1,189
Investment Company Portfolio Turnover 170.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of April 30, 2026)
Total Net Assets
$992,847,243
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
1,189
Portfolio Turnover Rate
170%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of April 30, 2026)
Portfolio Composition*  (% of Total Investments)
image
 [12]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
Class R5  
Shareholder Report [Line Items]  
Fund Name Putnam Income Fund
Class Name Class R5
Trading Symbol PINFX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam Income Fund for the period November 1, 2025, to April 30, 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 R5
$21
0.43%
[13],[14]
Expenses Paid, Amount $ 21
Expense Ratio, Percent 0.43%
Net Assets $ 992,847,243
Holdings Count | $ / shares 1,189
Investment Company Portfolio Turnover 170.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of April 30, 2026)
Total Net Assets
$992,847,243
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
1,189
Portfolio Turnover Rate
170%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of April 30, 2026)
Portfolio Composition*  (% of Total Investments)
image
 [15]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
Class R6  
Shareholder Report [Line Items]  
Fund Name Putnam Income Fund
Class Name Class R6
Trading Symbol PINHX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam Income Fund for the period November 1, 2025, to April 30, 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
$18
0.37%
[16],[17]
Expenses Paid, Amount $ 18
Expense Ratio, Percent 0.37%
Net Assets $ 992,847,243
Holdings Count | $ / shares 1,189
Investment Company Portfolio Turnover 170.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of April 30, 2026)
Total Net Assets
$992,847,243
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
1,189
Portfolio Turnover Rate
170%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of April 30, 2026)
Portfolio Composition*  (% of Total Investments)
image
 [18]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
Class Y  
Shareholder Report [Line Items]  
Fund Name Putnam Income Fund
Class Name Class Y
Trading Symbol PNCYX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Putnam Income Fund for the period November 1, 2025, to April 30, 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
$23
0.46%
[19],[20]
Expenses Paid, Amount $ 23
Expense Ratio, Percent 0.46%
Net Assets $ 992,847,243
Holdings Count | $ / shares 1,189
Investment Company Portfolio Turnover 170.00%
Additional Fund Statistics [Text Block]
KEY FUND STATISTICS (as of April 30, 2026)
Total Net Assets
$992,847,243
Total Number of Portfolio Holdings (excludes derivatives, except purchased options, if any)
1,189
Portfolio Turnover Rate
170%
Holdings [Text Block]
WHAT DID THE FUND INVEST IN? (as of April 30, 2026)
Portfolio Composition*  (% of Total Investments)
image
 [21]
Updated Prospectus Web Address https://www.franklintempleton.com/regulatory-fund-documents
[1]
* Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[2]
† Annualized.
[3]
* Does not include derivatives, except purchased options, if any.  
[4]
* Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[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.  
[13]
* Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[14]
† Annualized.
[15]
* Does not include derivatives, except purchased options, if any.  
[16]
* Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[17]
† Annualized.
[18]
* Does not include derivatives, except purchased options, if any.  
[19]
* Reflects fee waivers and/or expense reimbursements, without which expenses would have been higher.
[20]
† Annualized.
[21]
* Does not include derivatives, except purchased options, if any.