v3.25.4
S000004000 [Member] Expense Example, No Redemption - Putnam Sustainable Retirement 2030 Fund - Class C
Jul. 31, 2025
USD ($)
Prospectus [Line Items]  
Expense Example, No Redemption, 1 Year $ 173
Expense Example, No Redemption, 3 Years 536
Expense Example, No Redemption, 5 Years 1,057
Expense Example, No Redemption, 10 Years $ 2,296