S000003999 [Member] Annual Fund Operating Expenses - Putnam Sustainable Retirement 2035 Fund |
Jul. 31, 2025 |
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| Prospectus [Line Items] | ||||||||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | February 26, 2029 | |||||||||||
| Class R4 | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.48% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.32% | |||||||||||
| Acquired Fund Fees and Expenses | 0.69% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.49% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.64%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 0.85% | [5] | ||||||||||
| Class R5 | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.48% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.17% | |||||||||||
| Acquired Fund Fees and Expenses | 0.69% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.34% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.64%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 0.70% | [5] | ||||||||||
| Class R6 | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.48% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.07% | |||||||||||
| Acquired Fund Fees and Expenses | 0.69% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.24% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.64%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 0.60% | [5] | ||||||||||
| Class Y | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.48% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.17% | |||||||||||
| Acquired Fund Fees and Expenses | 0.69% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.34% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.64%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 0.70% | [5] | ||||||||||
| Class A | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.48% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.25% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.17% | |||||||||||
| Acquired Fund Fees and Expenses | 0.69% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.59% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.64%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 0.95% | [5] | ||||||||||
| Class C | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.48% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 1.00% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.17% | |||||||||||
| Acquired Fund Fees and Expenses | 0.69% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 2.34% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.64%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 1.70% | [5] | ||||||||||
| Class R | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.48% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.50% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.32% | |||||||||||
| Acquired Fund Fees and Expenses | 0.69% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.99% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.64%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 1.35% | [5] | ||||||||||
| Class R3 | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.48% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.25% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.32% | |||||||||||
| Acquired Fund Fees and Expenses | 0.69% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.74% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.64%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 1.10% | [5] | ||||||||||
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