S000003995 [Member] Annual Fund Operating Expenses - Putnam Sustainable Retirement 2050 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 Shares | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.51% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.33% | |||||||||||
| Acquired Fund Fees and Expenses | 0.67% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.51% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.66%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 0.85% | [5] | ||||||||||
| Class R5 Shares | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.51% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.19% | |||||||||||
| Acquired Fund Fees and Expenses | 0.67% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.37% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.67%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 0.70% | [5] | ||||||||||
| Class R3 Shares | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.51% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.25% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.33% | |||||||||||
| Acquired Fund Fees and Expenses | 0.67% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.76% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.66%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 1.10% | [5] | ||||||||||
| Class A Shares | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.51% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.25% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.18% | |||||||||||
| Acquired Fund Fees and Expenses | 0.67% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.61% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.66%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 0.95% | [5] | ||||||||||
| Class C Shares | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.51% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 1.00% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.18% | |||||||||||
| Acquired Fund Fees and Expenses | 0.67% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 2.36% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.66%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 1.70% | [5] | ||||||||||
| Class R Shares | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.51% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.50% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.34% | |||||||||||
| Acquired Fund Fees and Expenses | 0.67% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 2.02% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.67%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 1.35% | [5] | ||||||||||
| Class Y Shares | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.51% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.18% | |||||||||||
| Acquired Fund Fees and Expenses | 0.67% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.36% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.66%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 0.70% | [5] | ||||||||||
| Class R6 Shares | ||||||||||||
| Prospectus [Line Items] | ||||||||||||
| Management Fees (as a percentage of Assets) | 0.51% | [1] | ||||||||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||||||||
| Other Expenses (as a percentage of Assets): | 0.08% | |||||||||||
| Acquired Fund Fees and Expenses | 0.67% | [2] | ||||||||||
| Expenses (as a percentage of Assets) | 1.26% | [3] | ||||||||||
| Fee Waiver or Reimbursement | (0.66%) | [4] | ||||||||||
| Net Expenses (as a percentage of Assets) | 0.60% | [5] | ||||||||||
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